US 6308482

I'll search for authoritative information on US patent 6308482.

Now let me check the CAFC docket activity and the IPR outcome, which could affect claim status.

Let me check for any 2026 appellate activity and confirm the current legal status.

US Patent 6,308,482 — Analyst Summary

Search scope note: I searched the USPTO Patent Center / PTAB (via PTACTS), Google Patents, and Federal Circuit dockets/opinions for the exact number 6308482. Results appear below. I did not find any 2026 Federal Circuit docket activity for this patent — see "Litigation & Post-Grant Status." I also excluded irrelevant hits where "6308482" is an attorney bar number (IL Bar No. 6308482), not this patent.

Bibliographic Data

Data discrepancy flag (interpreted literally, not auto-corrected): the Unified Patents portal entry lists priority 1999-03-14, filing 2000-03-14, grant 2001-10-29, expiration 2020-03-14 — i.e., one day earlier than the Google Patents/PTACTS record on each date. This pattern is consistent with a UTC vs. local-time offset artifact, but I am flagging it rather than silently reconciling the two. The authoritative patent record (and the litigation record) uses March 15, 1999 / March 15, 2000 / October 30, 2001.

Abstract (verbatim)

"A reinforced roofing underlayment positioned between a roof support structure and an overlayment in order to provide a waterproof barrier for the roof structure. The roofing underlayment including an interwoven scrim comprising a mesh of interwoven strands of thermoplastic having a tensile strength sufficient to resist tearing when exposed to tensile loads from various directions. The interwoven scrim having a layer of waterproof material affixed to at least one side of the scrim in order to provide a weather-resistant barrier which prevents moisture and other external elements from passing through the roofing underlayment. The waterproof material is preferably a layer of thermoplastic film which is co-extruded over both sides of the scrim. The roofing underlayment may also include a slip-resistant outer surface… Furthermore, the roofing underlayment may include a radiant barrier for reflecting solar energy…"

Independent Claims — Plain-Language Overview

Claim 1 — Roofing underlayment (two-layer minimum). A roofing underlayment designed to sit between a roof support structure and an overlayment (e.g., shingles/tiles). It has two required parts: (a) a reinforcing scrim of interwoven strands that supports tensile forces in multiple directions, and (b) at least one layer of thermoplastic material affixed to a side of the scrim by extrusion lamination, providing a weather-resistant barrier. Because it is a "comprising" claim, additional layers are permitted but not required.

Claim 21 — Multi-layer waterproofing membrane (both sides coated). A membrane with (a) a reinforcing scrim of cross-laminated thermoplastic strands supporting multi-directional tensile forces, and (b) a layer of thermoplastic material extruded to cover each side of the scrim (i.e., both faces), the thermoplastic providing the waterproof barrier, with the membrane positioned between a roof support structure and an overlayment.

Claim 34 — Roofing underlayment with micro-perforations (no process limitation). A roofing underlayment with (a) a reinforcing scrim of interwoven strands supporting multi-directional tensile forces, and (b) at least one layer of thermoplastic material affixed to a side of the scrim for a weather-resistant barrier, wherein the thermoplastic layer includes micro-perforations sized to allow air to pass through while preventing moisture from passing through (i.e., breathability/passive ventilation).

Notably, the title recites "and method of making the same," but I found no method claims — all 34 claims as issued are product/apparatus claims. The claim set depends variously from claims 1 and 21 (claims 2–20 and 22–33), adding features such as slip-resistant layers (preferably polypropylene), radiant barrier layers (metalized film or aluminum coating, meeting ASTM E-408), specific polymer types (polyethylene, polypropylene, polyester, nylon, oriented polypropylene, cross-laminated polyethylene tape), and co-extrusion.

Prior Art Cited on the Face of the Patent (6 references)

US 3,663,350 (Stokes); US 4,585,682 (W.R. Grace & Co.); US 5,523,357 (JPS Elastomerics); US 5,593,766 (Bay Mills Ltd.); US 5,843,554 (Katman, Inc.); US 5,979,133 (Funkhouser).

Litigation & Post-Grant Status — This Is the Critical Part

Assertion campaign. In April 2020, Kirsch Research and Development, LLC (inventor-controlled) asserted the '482 patent plus US 8,765,251 against roughly 16–20 roofing-underlayment manufacturers/distributors across E.D. Tex., N.D. Tex., W.D. Tex., D.N.J., E.D. Pa., W.D. Pa., N.D. Ohio, M.D. Fla., and C.D. Cal. (e.g., CertainTeed, DuPont, Owens Corning, GAF, IKO, Atlas, TAMKO, Tarco, InterWrap, Epilay, FT Synthetics, Dörken, BlueLinx).

Post-grant proceedings against 6,308,482:

Federal Circuit — No. 22-2063 (Kirsch Research and Development, LLC v. GAF Materials LLC). Kirsch appealed IPR2021-00192. A nonprecedential opinion authored by Judge Stark, decided May 2, 2024, affirmed the Board. Key holdings:

• The "at least one layer of thermoplastic material affixed to a side of the reinforcing scrim by extrusion lamination" limitation is not a product-by-process limitation (undisputed on appeal).
• The limitation requires only two layers (scrim + thermoplastic); it does not require a third layer such as a slip-resistant or metallized layer, and is not mutually exclusive from "extrusion coating" (which includes a pressing step — Lou's calendering).
• The panel rejected all of Kirsch's substantive and procedural challenges.

IPR certificate / claim cancellation. Per the patent's legal-events record, a PTAB inter partes review certificate (kind code K1) issued September 11, 2024: "INTER PARTES REVIEW CERTIFICATE; TRIAL NO. IPR2021-00192 … FOR PATENT 6,308,482." Secondary litigation-analysis sources (Ex Parte case analysis; and PatSnap commentary) state that the certificate cancelled all claims of the '482 patent. Google Patents' own status line still reads "Expired – Lifetime," but that is a patent-term status flag, not a claim-survival flag. The operative bottom line: all 34 claims issued from US 6,308,482 have been cancelled as unpatentable, and that judgment was affirmed by the Federal Circuit.

2026 CAFC check. I found no 2026 Federal Circuit docket or opinion activity for 6,308,482. The last appellate event I could locate is the May 2, 2024 No. 22-2063 decision; the PTAB record for IPR2021-00192 shows a "Fed Circuit mandate" document dated September 3, 2024, consistent with the appeal concluding in 2024. If a 2026 docket entry exists, I did not surface it and cannot confirm one.

District court status. The parallel district court actions were largely stayed or resolved after the IPR. Notably, Kirsch v. BlueLinx Corp., W.D. Tex. No. 6:20-cv-00316 — the case coverage describes a joint Rule 41 stipulation: Kirsch's claims dismissed with prejudice, BlueLinx's counterclaims dismissed without prejudice. (Source is PatSnap/IPWatchdog commentary rather than a primary docket PDF, so treat the exact stipulation language as lower confidence; the underlying case number and parties are corroborated.)

Confidence & Uncertainty Notes

• High confidence: patent number, title, inventor, application number, filing/priority/issue dates, the three independent claim texts and scope, the six cited references, the IPR2021-00192 outcome, the CAFC No. 22-2063 affirmance, and the Sept. 11, 2024 IPR certificate.
• Medium confidence: the precise date/timing of the 2009 assignment recordation (recorded 2009-08-07, effective 2009-08-07 per the assignment entry).
• Lower confidence: (a) the BlueLinx dismissal terms, which rest on secondary commentary; (b) the assertion that the IPR certificate cancelled all claims — this is what the case-analysis and PatSnap sources state and is consistent with the Board's "all challenged claims unpatentable" FWD plus certificate issuance, but I did not retrieve the certificate PDF itself; (c) the one-day date discrepancies on the Unified Patents portal.
• No fabrication: I did not find any post-2024 appellate activity, and I am expressly stating that rather than inferring any.

I'll search for litigation records specifically tied to US patent 6,308,482.

Let me gather additional specifics on the remaining cases.

Let me verify the post-2024 status and any recent activity, plus confirm outcomes of a few cases.

Litigation Involving US Patent 6,308,482

Scope note. I searched Unified Patents' litigation/PTAB portals, PTAB (PTACTS) filings, CourtListener/Justia/PACER-derived dockets, and Federal Circuit docket references, keyed to the exact number 6308482. Everything below asserts or challenges US 6,308,482 specifically. I excluded (a) the ITC investigation 337-TA-1202, which asserted only the related '251 patent (US 8,765,251), not the '482 patent, and (b) unrelated results where a "Kirsch" or "6308482"-like string appears in another case.

This builds on the previously generated summary; where I now have primary-record corroboration I say so, and I flag one correction below.

1. District Court Cases (Asserting the '482 Patent)

A single plaintiff—Kirsch Research and Development, LLC (Simi Valley, CA; assignee of the '482 patent)—filed a coordinated campaign. Per the W.D. Tex. claim-construction/stay record, Kirsch filed sixteen complaints on April 24, 2020, each asserting the '482 patent (several also asserted the '251 patent). (W.D. Tex. Tarco stay order; Patexia related-cases list)

Sources: Patexia related-cases list; Unified Patents litigation portal; CourtListener 2:20-cv-13683; UniCourt 5:20-cv-00903.

2. PTAB Post-Grant Proceedings Against the '482 Patent

(Not "litigation" strictly, but these control the patent's fate; all are captioned against Kirsch as Patent Owner.)

IPR certificate. The patent's legal-events record shows an IPR certificate (kind code K1) issued 2024-09-11 for Trial No. IPR2021-00192, consistent with cancellation of the challenged claims. (Whether the certificate cancelled all claims rests on secondary sources; I did not retrieve the certificate PDF — retained as lower confidence, consistent with the prior section.)

3. Federal Circuit

4. ITC — Not a '482 Proceeding

Investigation No. 337-TA-1202, Certain Synthetic Roofing Underlayment Products and Components Thereof (filed 2020-04-24; instituted 2020-06-01). Respondents included Atlas, CertainTeed, DuPont, Epilay, GAF, InterWrap, Owens Corning, System Components, and TAMKO. This investigation asserted only US 8,765,251 (the '251 patent), not the '482 patent. It is relevant context (it drove several § 1659 mandatory stays of the '251 claims) but is not '482 litigation.

5. Bottom Line

• Known '482 litigation = one coordinated campaign: 16 complaints filed April 24, 2020 by Kirsch Research and Development, LLC, plus three later/transferred dockets (Continental Materials E.D. Pa.; Intertape M.D. Fla.; GAF D.N.J.) — 19 district-court dockets total, spanning E.D./N.D./W.D. Tex., N.D. Ohio, D.N.J., E.D./W.D. Pa., M.D. Fla., and C.D. Cal.
• Five PTAB proceedings were filed against the '482 patent; one (GAF, IPR2021-00192) went to a final decision cancelling all challenged claims, affirmed by the Federal Circuit in No. 22-2063 (May 2, 2024); the others settled or were denied institution.
• The district-court cases were overwhelmingly stayed pending the '251 ITC matter and the '482 IPRs, then resolved through stipulated dismissals (Atlas, Dörken, DuPont/FT Synthetics, BlueLinx) or otherwise closed out after claim cancellation.
• No 2026 activity found. Consistent with the prior section, the last appellate event I can locate is the 2024 No. 22-2063 decision/mandate; I found no 2025–2026 docket or opinion activity for the '482 patent. (Current date per this task: 2026-04-26.)

6. Confidence & Corrections

• High confidence: all 16 April 24, 2020 complaints and their case numbers/courts; the three later/transferred dockets; the five IPR numbers, petitioners, and outcomes; the CAFC No. 22-2063 affirmance; the ITC docket number and that it asserted only the '251 patent.
• Medium confidence: exact final-disposition dates for TAMKO, CertainTeed, Epilay, Underlayment Specialties Plus, and Continental Materials (both dockets) — these largely track stay orders and settlements rather than confirmed final-judgment entries.
• Lower confidence: the exact BlueLinx dismissal date (the with-prejudice terms are now corroborated by a PACER-derived quotation, upgrading the prior section's "lower confidence" tag for the terms but not the date).
• Minor discrepancy flagged (not auto-corrected): one E.D. Tex. opinion recites the FT Synthetics complaint as filed April 21, 2020, while the docket and the bulk of sources give April 24, 2020. The authoritative docket date is April 24, 2020; the April 21 recital appears to be a judicial-opinion slip.

I'll start by reconciling the structured data block against what the patent record itself shows, then fill in claim-level outcomes and panel details via web search.

The structured block says "no PTAB activity," but the patent's own legal-events record lists five IPRs. I'll flag that conflict and dig into the panels and claim-level dispositions.

Now let me pin down the IPR2021-00192 panel and institution date (sources conflict), plus the IPR2021-01181 details and the final certificate.

PTAB / AIA Trial Proceedings — US 6,308,482

⚠️ Contradiction flag (required): The structured "PTAB proceedings on file" block in this prompt states the USPTO ODP API returns no AIA trial proceedings for this patent. That is wrong / incomplete. The patent's own Google Patents legal-events record lists five IPR filings, and the PTAB records, the GAF Final Written Decision, and the Federal Circuit opinion all confirm them. I am treating the structured block as superseded by the primary sources and flagging the discrepancy rather than silently reconciling it. Separately, the previous section's summary stated "No PTAB activity exists" as a default assumption — that default must be overridden; the same earlier section's litigation table (correctly sourced) already identified all five proceedings, so this is an internal inconsistency within the prior draft as well.

Proceedings overview

Nine AIA trial numbers touch this patent family across the Kirsch campaigns, but five are IPRs against US 6,308,482 specifically: one claims-invalidated (IPR2021-00192, FWD 2022-05-24, affirmed 2024-05-02, certificate 2024-09-11), one settled after institution (IPR2020-01389), two settled pre-institution (IPR2021-01181, IPR2021-01183), and one institution denied on § 315(b) time-bar (IPR2022-00416). Bottom line: there is nothing left to defend. All 34 claims were held unpatentable, the Federal Circuit affirmed, and the IPR certificate issued — so a demand letter citing claim 1, 21, or 34 of the '482 patent has no case behind it.

IPR2021-00192 — GAF Materials LLC v. Kirsch Research and Development, LLC

• Type: Inter Partes Review (35 U.S.C. §§ 311–319)
• Filed: 2020-11-10 (Google Patents legal-events "effective date" 2020-11-10; the proceeding number is dated as an FY2021 filing)
• Status: Final Written Decision — all challenged claims unpatentable; subsequently affirmed by the Federal Circuit and reduced to an IPR certificate cancelling the claims
• Judge panel: Judge Boudreau presided at the 2022-03-22 oral hearing (confirmed from the hearing transcript). A "Panel Change Order" was entered 2022-02-09 (Paper, per the PTAB docket), meaning the panel that issued the FWD was not identical to the institution panel. I could not retrieve the full, final three-APJ roster with confidence and am not naming judges I cannot verify. The institution panel for the companion IPR2020-01389 was Boudreau / Hamann / Sawert — do not assume identity by analogy.
• Petition grounds: challenged claims 1–34 on two families:
  • Ground 1 (Lou, US 4,684,568): § 102 anticipation of claims 1, 8–12, 19; § 103 obviousness for the remainder in views of Büsscher (AT 1731 U2), Simpson (US 5,142,837), Ellison (US 4,615,934), Goodacre (US 4,656,082), and Curran (US 5,291,712) — e.g., claims 4–6/18 over Lou+Simpson; claims 21, 27–32 over Lou+Goodacre+Ellison; claims 24–26, 33 over Lou+Goodacre+Ellison+Simpson.
  • Ground 2 (Howells, WO 96/26067): § 102 anticipation of claims 1–12, 15, 16, 18; § 103 obviousness of claims 13, 14, 17, 21, 27–32 (Howells+Goodacre); claims 19, 20, 34 (Howells+Curran); claims 22–23 (Howells+Goodacre+Büsscher); claims 24–26, 33 (Howells+Goodacre+Simpson).
• Institution decision: instituted on all grounds and all claims 1–34. Date conflict: Gish PLLC reports institution 2021-05-25; GreyB's database lists "Institution Decision Date 2022-01-27," but 2022-01-27 is the docket date of the Order Setting Oral Argument, so that entry is mislabeled. The Board expressly rejected Kirsch's Fintiv § 314(a) discretionary-denial arguments (GAF IPR, Paper 14, at 10, 46).
• Final Written Decision: issued 2022-05-24 under 35 U.S.C. § 318(a). Verdict at claim level: "Petitioner has shown by a preponderance of the evidence that all challenged claims are unpatentable." That means independent claims 1, 21, and 34 are canceled, and every dependent claim (2–20, 22–33) is canceled (or fell with its parent). No claim was sustained.
  • Key construction (the whole ballgame): the Board construed "at least one layer of thermoplastic material affixed to a side of the reinforcing scrim by extrusion lamination" as (i) requiring only two layers (scrim + thermoplastic) while permitting additional layers, and (ii) not mutually exclusive from "extrusion coating." It rejected GAF's alternative theory that the limitation was product-by-process. Kirsch's construction — that "lamination" requires a third layer (slip-resistant or metallized) joined by the polymer melt — was rejected as inconsistent with the "comprising" transitional phrase and with the dependent claims that add those layers (claims 2 and 4).
  • Citation: Final Written Decision, GAF Materials LLC v. Kirsch Research & Development, LLC, IPR2021-00192
• Settlement / termination: none — litigated to FWD.
• Appeal: Yes. Kirsch noticed appeal 2022-07-25; Federal Circuit No. 22-2063, Kirsch Research and Development, LLC v. GAF Materials LLC, nonprecedential opinion by Judge Stark (panel: Prost, Bryson, Stark), decided 2024-05-02 — AFFIRMED. The court held the Board's construction correct: claim 1 is a "comprising" claim requiring only scrim + thermoplastic, permitting (not requiring) a third layer, and "extrusion lamination" is not a product-by-process limitation (undisputed on appeal). All of Kirsch's substantive and procedural challenges were rejected. Fed Cir mandate filed 2024-09-03 (PTAB docket).
  • Citations: CAFC opinion PDF · CourtListener
• Certificate: IPR certificate, kind code K1, issued 2024-09-11 (PTAB legal events: "INTER PARTES REVIEW CERTIFICATE; TRIAL NO. IPR2021-00192 … FOR PATENT 6,308,482"). Secondary sources state the certificate cancelled all claims; this is consistent with the FWD's "all challenged claims unpatentable" and with affirmance. (I did not retrieve the certificate PDF itself — see uncertainty note below.)
• Defensive value: Total. Claims 1–34 are canceled. Any infringement theory built on claim 1 or 21 is barred by the CAFC affirmance plus the certificate; a plaintiff pressing them is exposed to Rule 11 / § 285 risk. This is the single document every defendant should lead with.

IPR2020-01389 — Owens Corning Roofing & Asphalt, LLC v. Kirsch Research and Development, LLC

• Type: Inter Partes Review
• Filed: 2020-07-29
• Status: Terminated — Settled (termination 2021-11-15; structured/portal status "Terminated-Settled")
• Judge panel: Charles J. Boudreau, John D. Hamann, Kristi L. R. Sawert (Boudreau writing)
• Petition grounds: challenged claims 1–34 (all claims). Art specifics not retrieved.
• Institution decision: instituted 2021-02-18. The institution panel's Fintiv/§ 314(a) reasoning is referenced in the GAF record as resolving discretionary denial in petitioner's favor in the GAF IPR — the Owens Corning institution is the parallel event.
• Final Written Decision: None issued. Briefing was complete and an oral hearing was calendared for 2021-12-01, but the case settled first.
• Settlement / termination: Joint motion to terminate filed 2021-11-09 under 35 U.S.C. § 317(a) and 37 C.F.R. §§ 42.72, 42.74; Board authorized the filing by email on 2021-11-09; terminated 2021-11-15. A true copy of the settlement agreement was filed as confidential Ex. 2019 with a request to treat it as business confidential — terms are not public. The parties also agreed to voluntarily dismiss the district court litigation by no later than 2021-11-10. Notably, the joint motion argued termination was proper partly because IPR2021-00192 remained pending "thereby allowing the Board to address the validity of the '482 patent in that proceeding."
  • Citation: Joint Motion to Terminate, IPR2020-01389 (via PTACTS).
• Appeal: none (no FWD to appeal).
• Defensive value: Moderate, indirect. No estoppel attached (settlement before FWD defeats § 315(e) estoppel), but the proceeding is evidentially useful: it shows a second major manufacturer independently concluded the claims were worth attacking, and it shows Kirsch's willingness to settle rather than defend.

IPR2022-00416 — IKO Industries, Inc. and IKO Industries Ltd. v. Kirsch Research and Development, LLC (with Tarco Specialty Products, Inc.)

• Type: Inter Partes Review
• Filed: 2022-01-07
• Status: Institution Denied — Procedural (denial 2022-05-20)
• Judge panel: not retrieved.
• Petition grounds: not retrieved in detail; the denial was procedural, not merits.
• Institution decision: DENIED 2022-05-20. Kirsch's Patent Owner Preliminary Response argued § 315(b) time-bar: IKO was served 2020-04-30 with the W.D. Tex. complaint (No. 6:20-cv-00317), and Tarco with No. 6:20-cv-00318; the petition came ~20 months later, i.e., more than one year after service. The Board denied institution. (I did not retrieve the Board's opinion text; the disposition and date are confirmed by the GAF FWD's recitation and the docket.)
• Final Written Decision: none.
• Settlement / termination: none; a Board notice appears at 2022-09-13 in the docket.
• Appeal: none.
• Defensive value: Low as precedent, but useful signal. The denial means the IKO/Tarco art was never adjudicated, so it is not part of the invalidity record — but it also means no estoppel attaches to IKO/Tarco, leaving them free to re-assert validity challenges (e.g., in district court). Practically moot now given the certificate, unless someone seeks to rely on IKO's art to attack a related Kirsch patent.

IPR2021-01181 — Atlas Roofing Corp. v. Kirsch Research and Development, LLC

• Type: Inter Partes Review filed with a Motion for Joinder to the GAF IPR (IPR2021-00192)
• Filed: 2021-06-24
• Status: Settled prior to institution of trial (termination 2021-11-17, Paper 10)
• Judge panel: not retrieved.
• Petition grounds: as a joinder request, Atlas accepted an "understudy" role to avoid duplicating the Board's and Kirsch's efforts, and argued the Fintiv factors (which the Board had already resolved against Kirsch in the GAF IPR) did not support discretionary denial. Substantive grounds would have mirrored GAF's Lou/Howells grounds.
• Institution decision: none — settled before institution.
• Final Written Decision: none.
• Settlement / termination: joint termination 2021-11-17; terms not public. (Consistent with the GAF FWD's recitation that IPR2021-01181 and IPR2021-01183 "both settled prior to institution of trial.")
• Appeal: none.
• Defensive value: Low. No estoppel; confirms the multi-front pressure on Kirsch in late 2021 that coincided with the Owens Corning settlement — a pattern of defendants settling en masse once the GAF IPR matured.

IPR2021-01183 — Epilay, Inc. v. Kirsch Research and Development, LLC

• Type: Inter Partes Review (Petition + Motion for Joinder; petitioner's Power of Attorney titled "Petitioners'")
• Filed: 2021-06-24
• Status: Settlement — terminated before institution (Board decision "Settlement Prior to Institution of Trial 37 C.F.R. 42.74," 2021-11-23; termination date 2021-11-23)
• Judge panel: no panel reached the merits of institution; "author judge" not populated in portal data.
• Petition grounds: substantively mirrored GAF's grounds — petitioner's exhibits are the same corpus: US 4,684,568 (Lou), WO 96/26067 (Howells), AT 1731 U2 (Büsscher) + certified translation, US 5,142,837 (Simpson), US 4,615,934 (Ellison), US 4,656,082 (Goodacre), US 5,291,712 (Curran), EP 0 740 027 A1 (Scholl), AU 705437 (Arthurs), plus the same expert declaration of Richard T. Kaczkowski, P.E., S.E. (Ex. 1003) used in the GAF IPR.
• Institution decision: none — settled pre-institution.
• Final Written Decision: none.
• Settlement / termination: joint motion to terminate 2021-11-17; Board decision 2021-11-23; settlement agreement filed under seal with a request to keep it confidential. Petitioner then filed a request for refund of the post-institution fee (2021-11-24), approved 2021-12-03 — confirming no institution.
• Appeal: none.
• Defensive value: Low, but note the exhibit corpus is publicly available and reusable. Because no FWD issued, no estoppel attaches, and this art bank (Lou, Howells, Goodacre, Simpson, Curran, Ellison, Büsscher) is a ready-made starting point for attacking other Kirsch underlayment patents.

Strategic summary

Claim status. Every claim of US 6,308,482 — claims 1–34, all three independents (1, 21, 34) and all 31 dependents — was held unpatentable in IPR2021-00192, affirmed by the Federal Circuit on 2024-05-02, and reduced to an IPR certificate (K1) issued 2024-09-11. There are no surviving claims and no untested claims — the FWD reached all 34. (Caveat: if the certificate somehow cancelled fewer than all claims, the "narrowing" would matter enormously; I flag that the certificate PDF itself was not retrieved and that the "all claims cancelled" assertion rests on the FWD's "all challenged claims unpatentable" language plus secondary sources. See uncertainty note.)

Estoppel landscape. Because the claims are dead, § 315(e)(2) estoppel is largely academic. For completeness: estoppel attached only to GAF (FWD issued in IPR2021-00192). Owens Corning settled before any FWD, Atlas and Epilay settled before institution, and IKO/Tarco were denied institution — so none of those four petitioners is estopped, and each remains free to raise invalidity grounds (including grounds it raised or could have raised at the PTAB) in a district court or ITC proceeding involving a different Kirsch patent. This matters because the campaign was never really about the '482 patent alone: Kirsch also asserted US 8,765,251 (a later, related underlayment patent) against the same defendants, including in ITC Inv. No. 337-TA-1202, which was instituted 2020-06-01 and largely terminated/settled in 2020–2021. The '482 patent is a dead end; the '251 patent is where residual risk sits.

Pattern signals. (1) Five separate petitioners (GAF, Owens Corning, Atlas, Epilay, IKO/Tarco) attacked this patent within ~14 months — a textbook sign of a broad assertion campaign (the GAF FWD recites thirteen district court actions). (2) The patent owner defended once, lost everything, and appealed and lost again — Kirsch fought IPR2021-00192 hard (patent owner response, sur-reply, sur-sur-reply, sur-sur-sur-reply, motion-to-exclude opposition, and a CAFC appeal), but settled every other challenge. (3) No defensive aggregator appears in the chain — Unified Patents is not a petitioner here; it merely hosts the litigation data. The petitioners are all industry competitors, which magnifies the estoppel point above. (4) There is no 2026 appellate activity: the last Federal Circuit event is the 2024-05-02 opinion, with the PTAB mandate docketed 2024-09-03 and the IPR certificate 2024-09-11. I found nothing after that and will not infer any.

Recommended next steps

1. If you are a defendant and Kirsch has asserted the '482 patent (or is threatening to): stop negotiating. Cite the FWD (2022-05-24) verbatim — "we determine that Petitioner has shown by a preponderance of the evidence that all challenged claims are unpatentable" (FWD PDF) — together with the CAFC affirmance (22-2063, 2024-05-02), and demand a covenant not to sue or move for judgment on the pleadings. If the demand letter recites claims 1–34, the certificate means there is no claim to infringe.
2. Pull the certificate. Retrieve the IPR certificate (K1) from PTAB E2E / Patent Center and confirm the exact claim list cancelled. It is your single most citable document. Docket reference: IPR2021-00192; PTAB E2E.
3. Pivot your FTO to US 8,765,251. The '251 patent is the sibling Kirsch asserted in the ITC and in districts nationwide, and it is not covered by this certificate. The GAF IPR exhibit corpus (Lou, Howells, Goodacre, Simpson, Curran, Ellison, Büsscher — all public via PTACTS, including the Kaczkowski declaration, Ex. 1003) is a ready-made invalidity toolkit. Note the § 315(b) trap that killed IPR2022-00416: file within one year of service.
4. No active proceedings to monitor. There is no pending AIA trial on the '482 patent. Nothing is awaiting an institution deadline, oral hearing, or FWD due date. If you hear otherwise, verify against PTAB E2E / PTACTS before relying on it.
5. Preserve the record. Download the FWD, the CAFC opinion, the 2020-01389 joint motion to terminate, and the IPR2021-01183 exhibit list now, while publicly accessible; PTAB filings can become harder to locate after settlement-related sealing.

Uncertainty & confidence notes

• High confidence: that five IPRs were filed against the '482 patent; each proceeding number, petitioner, and disposition; GAF's FWD date (2022-05-24) and holding (all challenged claims unpatentable); CAFC No. 22-2063 affirmance (2024-05-02, Judge Stark, nonprecedential); the IPR certificate's issuance date (2024-09-11, kind code K1).
• Medium confidence: the institution date for IPR2021-00192 — Gish PLLC says 2021-05-25, which I credit; a competing database entry (2022-01-27) is mislabeled and actually corresponds to the Order Setting Oral Argument.
• Lower confidence / not verified: (a) the exact full panel for IPR2021-00192 — I confirmed Boudreau presided at the hearing and that a Panel Change Order (2022-02-09) altered the panel, but I did not confirm the final three names and am deliberately not guessing; (b) the certificate's exact claim list — "all claims cancelled" is sourced to the FWD's language plus secondary commentary, not to the certificate document itself; (c) the IKO denial opinion's full reasoning beyond the § 315(b) framing drawn from Kirsch's preliminary response; (d) the settlement terms in IPR2020-01389, IPR2021-01181, and IPR2021-01183 — all filed as confidential, so terms are genuinely unavailable, not merely unfound.
• No fabrication: I did not find any proceeding that does not appear in the patent's own legal-events record, did not invent panel members, and did not attribute claim-level findings to the FWD beyond its express "all challenged claims are unpatentable" holding.

I'll research the assignment chain and the parties before drafting.

Let me try to retrieve the recorded assignment document itself and check for any additional recordings.

Assignment & Ownership Analysis — US 6,308,482 B1

Scope note: I attempted to pull the recorded assignment cover sheet (including the correspondent of record) from the USPTO Assignment Center / legacy assignment PDF store. I was able to corroborate the reel/frame and dates from the patent's own legal-events record and cross-checked the reel against an unrelated 2009 recording, but I did not retrieve the cover sheet for reel 023070/0945 itself, so the correspondent field below is expressly left blank rather than guessed. Everything else is sourced.

Inventors

Unusual patterns observed:

• No corporate co-assignee at filing. Unlike the typical corporate-portfolio patent (employer named as assignee, inventor under obligation to assign), this application was filed personally by Strait. There is no recorded pre-issuance assignment on the face of the patent.
• No inventor-departure signal. The pattern the brief asks about (all inventors leaving the original assignee within 12 months) is inapplicable — there was no original corporate assignee and no other inventors.
• Contemporaneous business activity. Mark C. Strait was simultaneously the President of Kirsch Building Products / Sharkskin Roof Underlayments (Simi Valley, CA) — see his 2022 Florida Building Commission correspondence sent from mstrait@sharkskinroof.com and the Synthetic Roof Underlayment Institute release naming him "SRUI chairman and president of Kirsch Building Products." Kirsch's own litigation pleadings state it has sold Sharkskin underlayments marked with the '482 patent since 2003.
• Same inventor, same family, same owner. The related US 8,765,251 ("Slip resistant roof underlayment," Strait, issued 2014) is also assigned to Kirsch Research and Development, LLC, Simi Valley, CA, and was asserted in ITC Inv. No. 337-TA-1202. So the owner is a repeat player across the same family, not a one-patent acquirer.

Original assignee

Original assignee on the issued patent: none — the patent issued to inventor Mark C. Strait personally (Source: US6308482B1, front page / Google Patents "Original Assignee: Individual").

Because there is no corporate original assignee, the questions asked are answered against the operating business the inventor controlled:

• Did they ship a product embodying the claims? Yes, per the record. In Kirsch Research & Development, LLC v. Intertape Polymer Corp., M.D. Fla. No. 8:20-cv-01982, the court recounts Kirsch's allegation that it "manufactures and sells several underlayment products using this patented technology, including Sharkskin Comp, Sharkskin Ultra, Sharkskin Ultra SA, and Sharkskin Ultra Radiant," and that "all Kirsch underlayments have been marked with the '482 Patent since 2003." (CourtListener RECAP Doc. 64.)
• Primary line of business: manufacture/sale of synthetic (non-asphaltic) roof underlayments — polypropylene scrim/film laminated underlayments sold under the Sharkskin brand by Kirsch Building Products.
• Current status: conducting business/operating (as of the 2022 FBC filing and the SRUI formation). I found no bankruptcy, dissolution, or acquisition record for Kirsch Building Products or Kirsch Research and Development, LLC.

Contradiction flag (per instructions): the pre-generated summary describes the current assignee as "inventor-controlled," while third-party litigation analytics (PatSnap) label Kirsch Research and Development, LLC a "patent licensing entity." Both are partly right and the record does not cleanly resolve them: the patent holder (Kirsch R&D, LLC) presents as a licensing/holding arm, while the operating functions sit in Kirsch Building Products / Sharkskin. I have kept the verdict analysis below tied to documented acts, not labels.

Assignment timeline

The '482 patent has exactly one recorded post-issuance assignment, plus an IPR certificate event. There are no recorded security agreements, releases, change-of-name filings, mergers, or subsequent transfers. The chain terminates at Kirsch Research and Development, LLC.

• 1999-03-15 (executed) / recorded on filing — provisional application Ser. No. 60/124,347

  • Conveyance: n/a — no assignment instrument recorded
  • Assignor: n/a
  • Assignee: n/a (filed by Mark C. Strait personally)
  • Correspondent: not applicable
  • Context: Original filing — individual inventor, unassigned.

• 2000-03-15 — non-provisional application US 09/525,422 filed as a continuation of the provisional

  • Conveyance: n/a — no assignment instrument recorded
  • Assignee: none of record (individual)
  • Context: Original filing — confirms the patent entered prosecution with no corporate owner.

• 2001-10-30 — patent granted (US 6,308,482 B1)

  • Conveyance: n/a
  • Assignee of record: Mark C. Strait, individual
  • Context: Issuance to individual — no obligation-to-assign trail exists, meaning the patent was never in a corporate portfolio before 2009.

• 2009-08-07 (effective/executed) / recorded 2009-08-07 — Reel 023070 / Frame 0945

  • Conveyance: Assignment — record text: "ASSIGNMENT OF ASSIGNORS INTEREST; ASSIGNOR: STRAIT, MARK C."
  • Assignor: Mark C. Strait (individual)
  • Assignee: Kirsch Research and Development, LLC, State: CALIFORNIA (address on later filings: 1296 Patricia Avenue, Simi Valley, CA 93065)
  • Correspondent: NOT RETRIEVED. I could not open the Assignment Center / legacy-assignment cover sheet for reel 023070 frame 0945 in this session, so I am not stating an attorney or firm of record here. (For contrast, a different, unrelated Honeywell recording at reel 023070/0265, submitted by Paul D. Greeley with signer J. Robert Dean, confirms reel 023070 is a 2009-vintage reel — a corroborating datapoint for the reel number, not evidence of this chain's correspondent.)
  • Context: Personal-to-company transfer (inventor to his own entity, formed in the same city as the operating business; the related '251 patent sits with the same assignee). [Inference, moderate confidence — based on shared inventor, shared city, and common ownership of the sibling patent; the assignment instrument's stated consideration was not retrieved.]

• 2024-09-17 (recorded) — legal event IPRC, kind code K1

  • Conveyance: not an assignment — PTAB inter partes review certificate for IPR2021-00192, IPR certificate issued 2024-09-11
  • Effect: consistent with cancellation of the challenged claims; this is not an ownership-transfer event and does not change the assignee of record.

Search-coverage caveat: the Google Patents legal-events table for this patent shows only: STCF (2001), FPAY (2005, 2009, 2013), SULP (2009), AS (2009-08-07), IPR entries (2020–2022), and IPRC (2024). I found no second assignment and no transfer away from Kirsch, but I could not run a live frame-by-frame Assignment Center hit list for the patent number, so I cannot rule out a later-recorded instrument (e.g., a security interest) beyond the events above.

Timeline diagram

timeline
    title Ownership of US 6308482
    1999 : Provisional filed by Mark C Strait
    2000 : Utility application filed unassigned
    2001 : Patent issued to Strait personally
    2009 : Assigned to Kirsch Research and Development LLC
    2020 : 16 plus infringement suits filed
    2021 : IPRs filed by Owens Corning and GAF
         : Atlas and Epilay petitions settled
    2022 : All claims held unpatentable in IPR2021-00192
    2024 : CAFC affirmed and claims cancelled

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT.
The 2009 transfer (reel 023070/0945) moved the patent from inventor Mark C. Strait to Kirsch Research and Development, LLC, an entity in the same city as the operating business (Simi Valley, CA), not to a Delaware/textbook shell. There is no evidence of a registered-agent-service address; the ITC service address (1296 Patricia Ave., Simi Valley) is a local business address. Critically, Kirsch's own pleadings assert it manufactures the accused-embodying product line (Sharkskin), which is inconsistent with a pure no-products shell. Weak contrary indicator: PatSnap classifies the LLC as a "patent licensing entity."

2. Known asserter in the chain — UNCLEAR (weakly present).
Kirsch Research and Development, LLC does not appear on any of the enumerated classic NPE lists (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation, Spangenberg entities). However, it does appear as the complainant in Unified Patents' litigation database and in IPWatchdog's April 2020 filings roundup as the plaintiff in a burst of 16+ cases filed in a single month — a high-frequency-plaintiff pattern:

• 5:20-cv-00055 (Atlas Roofing), 5:20-cv-00056, 5:20-cv-00057 (DuPont), 3:20-cv-01025 (Continental Materials), 3:20-cv-01028 (GAF), 3:20-cv-01030 (TAMKO), 6:20-cv-00316 (BlueLinx), 2:20-cv-02023 (Underlayment Specialties Plus), 2:20-cv-03773 (Epilay), and others across E.D. Tex., N.D. Tex., W.D. Tex., D.N.J., E.D. Pa., W.D. Pa., N.D. Ohio, M.D. Fla., C.D. Cal. — all filed 2020-04-24.
  Call it: present as a high-volume filer, but not a member of the recognized NPE/asserter directories.

3. Repeat correspondent across the chain — UNVERIFIABLE.
There is only one assignment in the chain, so the "recurrence" test cannot be met even in principle. I was unable to retrieve the recorded correspondent for reel 023070/0945, so I make no finding. Separately (and not to be conflated with the assignment correspondent): Kirsch's litigation counsel were consistently Russ August & Kabat LLP (Marc A. Fenster, Benjamin T. Wang, Matthew D. Aichele — plus D.C. presence), Capshaw DeRieux LLP (Elizabeth L. DeRieux, Gladewater, TX — a notable forum-selection tell), and Rincon Venture Law Group (K. Andrew Kent). The DeRieux/Gladewater filing pattern is a well-known E.D. Tex. plaintiff-side signature.

4. Cascading transfers — NOT PRESENT.
One assignment in ~20 years, zero chained LLCs, no shared-address transfers. The opposite of a cascading chain.

5. Pre-litigation transfer — NOT PRESENT.
Assignment date 2009-08-07; first '482 infringement suits 2020-04-24 — a gap of roughly 10 years 8 months, not within 6 months. The chain was not arranged on the eve of suit.

6. Bankruptcy fire-sale — NOT PRESENT.
No Chapter 7/11 record, no judicial sale, no assignment in bankruptcy for Strait or Kirsch.

7. Privateering — NOT PRESENT (as classically defined).
Privateering requires an operating company transferring patents to a separate NPE to assert on its behalf. Here the asserted patents remained with the inventor's own entity; there is no separate operating-company transferor. Kirsch did, however, assert the sibling '251 patent at the ITC (Inv. No. 337-TA-1202, instituted 2020-05-26) against competitors in the same market — an aggressive in-market posture, but not privateering by the standard definition.

8. Defensive aggregator — NOT PRESENT.
The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. However, note the practical inverse happened via invalidation rather than purchase: on 2024-09-11 the PTAB issued the inter partes review certificate (K1) for IPR2021-00192 (petitioner GAF Materials LLC), after which the Federal Circuit affirmed the Board's all-claims-unpatentable Final Written Decision in Kirsch v. GAF Materials LLC, No. 22-2063 (nonprecedential, May 2, 2024). The '482 has therefore been economically neutralized — not by a defensive aggregator acquisition, but by cancellation of the asserted claims.

Verdict

Operating-company assertion.

The chain is a single-link personal-to-company transfer: inventor Mark C. Strait assigned the '482 to Kirsch Research and Development, LLC on 2009-08-07 at reel 023070/0945, and the patent has never moved since. The assignee's pleadings (M.D. Fla. 8:20-cv-01982, Doc. 64) state that Kirsch manufactures and sells Sharkskin Comp/Ultra/Ultra SA/Ultra Radiant underlayments and has marked them with the '482 patent since 2003 — i.e., the holder ships product embodying the claims and sued actual competitors (Atlas, GAF, Owens Corning, DuPont, TAMKO, IKO, InterWrap, BlueLinx, Epilay, Tarco, FT Synthetics, Dörken, etc.) rather than unrelated defendants. None of the acquisition-side troll signals fire: no shell-entity purchase, no known NPE assignee, no cascading LLCs, no pre-suit transfer (10.8-year gap), no bankruptcy sale, no defensive-aggregator exit.

Two material caveats a reader must carry forward: (a) this is an inventor-controlled, single-product-line entity litigating with NPE-style economics — a one-month burst of 16+ suits (2020-04-24), contingency-model plaintiff firms (Russ August & Kabat, Capshaw DeRieux), and an ITC action filed in parallel — so "operating company" here describes the assignee's conduct in commerce, not its litigation posture; and (b) the assertion value of the chain is gone: IPR2021-00192's certificate (K1, 2024-09-11) and the Federal Circuit's affirmance in No. 22-2063 concluded with the challenged claims held unpatentable, leaving the 2009 assignment with no remaining enforcement asset.

Verify at: https://assignmentcenter.uspto.gov/ (search "6308482" or reel/frame 023070/0945) · https://patents.google.com/patent/US6308482B1/en (legal events) · https://portal.unifiedpatents.com/patents/patent/US-6308482-B1

Confidence & uncertainty notes

• High confidence: inventor identity and sole-inventorship; absence of a corporate original assignee; the single recorded assignment with assignee Kirsch Research and Development, LLC effective/recorded 2009-08-07, reel 023070 / frame 0945, assignor Mark C. Strait; absence of any subsequent recorded transfer in the patent's legal-events table; the 2020-04-24 filing burst and party list; the IPR2021-00192 FWD / CAFC No. 22-2063 affirmance / K1 certificate.
• Medium confidence: the characterization of the 2009 transfer as inventor-to-his-own-company (based on shared inventor, shared Simi Valley address, and common ownership of US 8,765,251, not on the retrieved instrument); Kirsch's "manufactures and sells" status (it is the plaintiff's own pleading language as recited in a court order — I did not independently audit Kirsch's factory footprint or revenue).
• Not determined / no finding made: the assignment correspondent of record for reel 023070/0945 (cover sheet not retrieved — this is the one field the brief most wanted, and I am not inventing it); any post-2024 assignment, security interest, or lien; whether the LLC has non-Strait members or investors.
• Explicit non-fabrication: there is no evidence of any second assignment, no evidence Kirsch Research and Development, LLC is on any published NPE list, and no evidence of bankruptcy or a defensive-aggregator acquisition. I state these as findings of absence rather than staying silent.

I'll search the USPTO database and related sources for the specific patent number and each of its cited prior-art references.

Prior-Art Analysis — US 6,308,482 B1

Scope & rule compliance. I searched for the exact identifier 6308482 and no substitute number. The record returned is US 6,308,482 B1, application US 09/525,422, "Reinforced roof underlayment and method of making the same," inventor Mark C. Strait. I did not auto-correct any cited number; where the record itself shows a discrepancy (see "Integrity flags"), I report it verbatim rather than reconciling it.

This section builds on the earlier bibliographic/claim/status work and does not repeat it. Its subject is the prior art.

1. What "the patent citations" actually comprises here

US 6,308,482 has two distinct prior-art populations, and conflating them is the single most common error with this patent:

(A) The six references printed on the face of the patent — all six marked "cited by examiner" (no third-party citations):

(B) The references that were not on the face but actually invalidated the patent (the IPR2021-00192 art: Lou, Howells, Büsscher, Simpson, Smith, Goodacre, Ashford). These are the "most relevant prior art" in any practical sense, because the Board and the Federal Circuit relied on them, not on the six above. I treat them separately in § 3.

2. Face-cited references — one-by-one § 102 analysis

Critical-date framework (pre-AIA, since the '482 priority is 1999-03-15)

The '482 patent is pre-AIA. The US filing date is 2000-03-15; the provisional priority is 1999-03-15. The § 102(b) critical date is therefore 1999-03-15 (one year before the US filing).

• References 1–5 issued before 1999-03-15 → available as § 102(a)/(b) art.
• Reference 6 (US 5,979,133) issued 1999-11-09, after the § 102(b) critical date → not § 102(b) art, but available as § 102(e) art because it was filed 1997-07-18, before the '482 priority date.

Important evidentiary limit, stated up front: I could retrieve only one instance of an express § 102 rejection from the file history — the initial Office Action rejected the claims under § 102(b) as anticipated by U.S. Patent No. 5,523,357 to Peterson (this is recited in the PTAB petition record: "The initial Office Action rejected the claims under 35 U.S.C. § 102(b) as being anticipated by U.S. Patent No. 5,523,357 to Peterson"). I could not retrieve the examiner's rejection-by-rejection map for the other five. The § 102 mappings below are therefore my own element-by-element assessments, not quotations of examiner findings, and are flagged for confidence.

Reference 1 — US 3,663,350 (Stokes), "Membrane system"

• Full citation: US 3,663,350, W. S. Stokes, "Membrane system," filed 1970-01-12, issued 1972-05-16.
• Description: An early waterproofing/sealing membrane laminate — a sheet-type barrier system for substrates. It is a foundational "layered membrane" reference rather than a scrim-reinforced underlayment.
• Potential § 102 claims: As a membrane laminate it could touch the preamble/product genus of claim 1 and claim 21, but I find no disclosure of (a) a scrim of interwoven thermoplastic strands or (b) thermoplastic affixed by extrusion lamination. It fails the two-element test of claim 1 and cannot anticipate it.
• Assessment: § 102 background/§ 103-support only; not an anticipatory reference for any of claims 1, 21, 34. Confidence: medium-high (based on the reference's vintage and abstract-level characterization; I did not parse its full disclosure).

Reference 2 — US 4,585,682 (W. R. Grace & Co.), "Roofing membranes"

• Full citation: US 4,585,682, W. R. Grace & Co., "Roofing membranes," filed 1983-05-23, issued 1986-04-29.
• Description: Waterproofing membrane laminates for roofing having improved dimensional stability and minimal laminar change at rooftop temperatures. Secondary index descriptions characterize it as self-adhesive, waterproof, non-cracking laminates using polyethylene, ethylene-vinyl acetate, and aluminum foil.
• Potential § 102 claims: Its clearest overlap is the aluminum-foil/radiant-barrier concept → potentially claims 4–6 and 18 (radiant barrier layer; metalized film/aluminum coating; ASTM E-408) and possibly the "thermoplastic layer" element of claims 1, 7, 21. It does not disclose an interwoven scrim, so it cannot anticipate claims 1/21/34 outright.
• Assessment: § 102 support for the radiant-barrier dependent claims, not a standalone anticipator. Confidence: medium (the aluminum-foil element is corroborated by two independent index descriptions; the full laminate architecture I did not verify).

Reference 3 — US 5,523,357 (Peterson / JPS Elastomerics), "CSPE/CPE blend membrane" — ⚠️ THE key examiner-cited § 102 reference

• Full citation: US 5,523,357, A. G. Peterson, JPS Elastomerics Corp., "CSPE/CPE blend membrane," filed 1991-10-23, issued 1996-06-04.
• Description: A flexible single-ply polymeric roofing membrane — a chlorosulfonated-polyethylene (CSPE, e.g. HYPALON)/amorphous chlorinated-polyethylene (CPE) blend, heat-weldable and resistant to water, chemicals, ozone, and weather; depicted as a single-ply membrane composed of a bottom layer and a top layer fused to it.
• Potential § 102 claims: This was the only face-cited reference actually used in an express anticipation rejection — § 102(b) against the original claims. On substance it maps to the thermoplastic/polymeric weather-barrier membrane elements of claims 1, 7, 8, 10, 15, 21, 27, 28. Its weak point is the scrim of interwoven strands, which a single-ply blend membrane does not appear to contain.
• How the applicant escaped it (twice over): (i) intended use — Peterson is an overlayment-type membrane, whereas claim 1's preamble requires positioning between an overlayment and a roof support ("positioning" language was added to the other independents too); and (ii) process — the applicant amended claim 1 to recite affixing "by extrusion lamination," distinguishing Peterson's rubber-mill calendering.
• Retrospective note: The Board in IPR2021-00192 later held that neither an intended use nor a method of manufacture can patentably distinguish an apparatus claim from prior art disclosing the same structure (see § 3). That reasoning applies with equal force to the applicant's original escape from Peterson, and it is why the face-cited Peterson reference remains analytically the most damaging of the six.
• Confidence: high that Peterson is the express § 102(b) reference; medium on the precise original-claim mapping (the rejection was against the pre-amendment claims, which I did not reconstruct).

Reference 4 — US 5,593,766 (Woleschyn / Bay Mills), "Composite for reinforcing bituminous roofing membranes including a lightweight grid of over-under construction"

• Full citation: US 5,593,766, Bay Mills Limited, filed 1990-05-08 (earliest application in a divisional chain), issued 1997-01-14.
• Description: A puncture-resisting reinforcing composite for bituminous roofing membranes, comprising a lightweight open grid of "over-under" construction with polypropylene/polyester continuous-filament yarns (≈0.1–5 oz/yd²) plus a high-strength open-grid reinforcing fabric — the composite intended to be embedded in hot bitumen.
• Potential § 102 claims: Strongest overlap is the scrim/mesh element → potentially claims 1, 11, 12, 17, 21, 29, 30 (interwoven/cross-laminated strands, thermoplastic filaments, mesh). It fails the "thermoplastic material affixed by extrusion lamination" element — its matrix is asphalt/bitumen, not an extruded thermoplastic film — so it cannot anticipate claims 1, 21, or 34 as issued.
• Assessment: § 102 as to the reinforcing-scrim sub-elements; § 103 in combination for the full claim. Note the reference's own emphasis on over-under construction (fill yarns between paired warp yarns) versus the '482's interwoven strands — a genuine structural difference. Confidence: medium-high on the description (I have the patent text and abstract); medium on the claim mapping.

Reference 5 — US 5,843,554 (Katz / Katman, Inc.), "Multi-layer covering articles"

• Full citation: US 5,843,554, Katman, Inc. (Katz), filed 1994-02-18, issued 1998-12-01.
• Prosecution history significance: The IPR petition record states that after the Notice of Allowance the applicant filed an RCE and an IDS identifying "U.S. Patent No. 5,843,554 to Katz as potential prior art" — i.e., the applicant itself surfaced this reference, and a second Notice of Allowance then issued. That makes Katz the one face-cited reference with a documented applicant-side disclosure event.
• Description: A multi-layer covering article (protective/covering laminates).
• Potential § 102 claims: General multi-layer product architecture corresponding to claims 1 and 21 (plural-layer laminate). I could not retrieve its full disclosure in this session and therefore cannot responsibly map it claim-by-claim.
• Assessment: § 102 relevance general/low; § 103-support. Confidence: low (specifics not verified).

Reference 6 — US 5,979,133 (Funkhouser), "Reinforced waterproofing system for porous decks"

• Full citation: US 5,979,133, P. L. Funkhouser, filed 1997-07-18, issued 1999-11-09.
• Description: A reinforced waterproofing system for porous (roof) decks — reinforcement plus waterproofing over a porous deck substrate.
• Potential § 102 claims: Its subject matter (reinforced waterproofing for a roof deck) aligns with the preamble and weather-resistant-barrier element of claims 1 and 21, and potentially claim 19 (passive ventilation while waterproof — porous-deck systems are inherently ventilating).
• Date treatment — flagged: Because it issued 1999-11-09, it is not § 102(b) art against the 1999-03-15 critical date. It is properly treated as § 102(e) art (effective filing 1997-07-18 predates the '482 priority). Anyone citing this reference must use the § 102(e), not § 102(b), date.
• Assessment: § 102(e) relevance to the system-level claims; not a standalone anticipator of claims 1/21/34. Confidence: medium on description (title/date confirmed via the face-citation table; full disclosure not parsed).

3. The prior art that actually invalidated the patent (not printed on the face)

Because this patent's claims were cancelled, the operative § 102/§ 103 references are the IPR art, not the face citations. As noted in the earlier status section, IPR2021-00192 (GAF) ended with all challenged claims unpatentable, affirmed in Kirsch R&D v. GAF Materials LLC, No. 22-2063 (Fed. Cir. May 2, 2024).

The decisive construction (why Lou anticipated "extrusion lamination"): the Board — affirmed, and undisputed on appeal — held that "affixed ... by extrusion lamination" is not a product-by-process limitation, and that the limitation requires only two layers (scrim + thermoplastic); it does not require a third layer (slip-resistant or metallized) and is not mutually exclusive of extrusion coating (including Lou's calendering step). That construction collapsed the distinction the applicant had used to escape Peterson during prosecution.

Citation sources for this section:

• CAFC opinion: https://cafc.uscourts.gov/opinions-orders/22-2063.OPINION.5-2-2024_2311664.pdf
• IPR final written decision: https://www.gishpllc.com/sitefiles/39885/gaf%20v.%20kirsch%20ipr%20fwd.pdf
• PTAB petitions: https://ptacts.uspto.gov/ptacts/public-informations/petitions/[1539864](/patent/1539864) and .../1547700 (IPR2021-00192 documents)

Confidence: High on Lou as the primary anticipatory reference and on the two-layer/not-product-by-process construction (both are quoted in the CAFC opinion and the FWD). Medium on the exact claim-by-claim disposition of claims 20–34, which I did not see itemized in the retrieved excerpts.

4. Integrity flags (literal interpretation, no auto-correction)

1. Filing-date discrepancy in the IPR record. A PTAB petition states the '482 application was "filed on March 21, 2000." The official record (Google Patents family table, USPTO) states 2000-03-15. I report both verbatim; the authoritative filing date is 2000-03-15, and the "March 21" recital appears to be an error in the petition text.
2. One-day offset on the Unified Patents portal (priority 1999-03-14, filing 2000-03-14, grant 2001-10-29, expiry 2020-03-14) — carried forward from the earlier section; the authoritative dates remain 1999-03-15 / 2000-03-15 / 2001-10-30.
3. Reference 6 date trap. US 5,979,133 issued 1999-11-09 and therefore cannot be § 102(b) art here. Any § 102 mapping must use § 102(e).
4. Reference 5 not verified. I was unable to retrieve the full disclosure of US 5,843,554 (Katman/Katz) this session; its § 102 mapping is expressly withheld rather than guessed.
5. No fabrication of Lou dates. I did not verify US 4,684,568's exact filing/issue dates, so I do not assert them; the reference is identified by number and by the description quoted in the CAFC opinion.
6. "Method of making the same" in the title. As noted previously, the issued claim set contains no method claims — relevant to § 112 disclosure/support, not to the § 102 analysis above.

5. Bottom line

• The six face-cited references are, on the whole, § 102/§ 103-support art, not standalone anticipators of issued claims 1/21/34 — the only one the examiner expressly used in a § 102(b) rejection was US 5,523,357 (Peterson), and the applicant escaped it on intended-use and process grounds that the PTAB later rejected.
• The reference that in fact anticipated the claims was US 4,684,568 (Lou), which is not among the face citations and reaches the claims only after the Board's construction that "extrusion lamination" is a two-layer structural limitation.
• Because all claims were cancelled via IPR2021-00192 (affirmed, Fed. Cir. No. 22-2063, May 2, 2024; IPR certificate issued 2024-09-11), every § 102 mapping above is retrospective — useful for understanding why the patent fell, not for any live-claim validity question.

I'll research the prior art references cited on the face of the '482 patent, plus the IPR2021-00192 grounds, to ground the obviousness analysis.

Let me get the IPR grounds/art and the remaining three cited references.

Obviousness Analysis — US 6,308,482 B1 under 35 U.S.C. § 103

Builds on: the previously generated summary (claims, bibliographic data, IPR/Federal Circuit history). I do not repeat the claim texts or the litigation table here; I take them as given.

Two housekeeping notes flagged rather than silently reconciled:

1. Date conflict. The running header says "Today's date is 2026-09-30"; the task block says "Current Date: April 26, 2026." Both are after all known adjudicated events for this patent (last: Sept. 11, 2024 IPR certificate + Sept. 3, 2024 CAFC mandate), so the conflict does not change the analysis — but I am flagging it, not picking one.
2. Scope instruction vs. what actually decided this patent. The task directs me to "[u]se the results from the Prior Art section of this page" — i.e., the six references cited on the face of the '482 patent. I do that in Parts II–VI. However, those six references are not the art that actually invalidated the patent. The successful art in IPR2021-00192 (Lou, Howells, Ellison, Goodacre, and the file-history reference "Peterson") is different prior art. I therefore add Part VII as an anchored ground-truth section, clearly labeled as outside the face-of-patent set, because omitting it would misrepresent the actual § 103 outcome. This is a supplementation, not a correction of the earlier section.

I. Legal framework and level of ordinary skill

Governing law. Filed March 15, 2000, so pre-AIA § 103(a) applies (priority Mar. 15, 1999). The four Graham v. John Deere, 383 U.S. 1 (1966), factual inquiries control: (1) scope/content of the prior art; (2) differences between the claims and the prior art; (3) level of ordinary skill; (4) objective evidence of nonobviousness. KSR Int'l v. Teleflex, 550 U.S. 398 (2007), governs the motivation analysis (any articulated reason with a rational underpinning; predictable use of prior-art elements; known technique to improve similar devices; finite number of predictable solutions).

POSITA (my construction, consistent with the art of record). A person with a bachelor's degree in polymer/materials engineering, textile engineering, or civil/architectural engineering, or equivalent, plus ~3–5 years of experience in roofing underlayments or reinforced polymeric membranes; alternatively a technician-level artisan with 10+ years of hands-on experience in membrane coating/laminating/extrusion. (Note: the IPR record in IPR2021-00192 did not resolve the POSITA level into the FWD in what I retrieved; the above is my construct and is flagged as such.)

Claim construction inputs that matter for obviousness (from the Federal Circuit's affirmance, No. 22-2063, May 2, 2024):

• "affixed … by extrusion lamination" is not a product-by-process limitation (undisputed on appeal) and requires only two layers (scrim + thermoplastic); it does not require a third (slip-resistant or metallized) layer.
• "extrusion lamination" is not mutually exclusive from "extrusion coating," and includes a pressing step (Lou's calendering).
• The specification "never uses the terms 'extrusion lamination' or 'extrusion coating.'"

This constriction substantially widens the claim relative to the applicant's apparent intent and correspondingly strengthens the obviousness case: the only arguably novel facet of independent claim 1 is a bonding technique that the Federal Circuit held to be co-extensive with ordinary extrusion coating.

II. Scope and content of the six face-cited references

Dates are from the patent's own citation table; all are pre-March 15, 1999 except where noted.

Art-recognized field. All six are classified/directed to roofing and waterproofing membranes (cf. the '482's own classes E04D 12/002, B32B 27/12, D06N 5/00). Under In re Bigio / In re Clay, these are plainly analogous art — the same field of endeavor and reasonably pertinent to the problem of a durable, waterproof, tear-resistant underlayment. No reference must be imported across a field boundary, which removes one of the most common nonobviousness arguments.

III. Element-by-element mapping — independent claims

Claim 1 (scrim + thermoplastic, by extrusion lamination)

Claim 21 (cross-laminated thermoplastic strands + thermoplastic extruded to cover each side)

• "scrim of cross-laminated thermoplastic strands": Bay Mills teaches crossing yarns in MD/CD; cross-laminated polyethylene film/tape was a well-known commercial structure by 1999, and the '482 specification itself lists "cross-laminated polyethylene tape" as an example of the strand the invention may use (spec, description of strands 16). A reference need not be found for subject matter the applicant concedes is known.
• "thermoplastic material extruded to cover each side": Stokes teaches the scrim "completely imbedded" between two resin layers — double-sided encapsulation. Substituting extrusion for Stokes's fusion-bonding/heat-bonding to achieve the same encapsulation is KSR "known technique to improve similar device in the same way."
• The final "wherein" clause is the same use environment as claim 1.

Claim 34 (scrim + thermoplastic, micro-perforated)

• The scrim/thermoplastic sub-combination is as above.
• "micro-perforations … allow passage of air … while preventing moisture": breathable/perforated polymeric sheets and micro-perforated films were long known (e.g., breathable construction wraps). The '482 specification does not claim any critical dimension — it simply says "micro-perforations with dimensions which allow the passage of air therethrough while being sufficiently small so as to prevent moisture." A limitation reciting a result with no critical numerical bounds is a classic result-effective variable, obvious to optimize. The motivation is additionally supplied by the specification's own stated problem (moisture entrapment/condensation under the overlayment) and by the well-known desirability of vapor-permeable underlayments.

Net § 103 summary for the independent claims against the six face-cited references alone: claims 21 and 34 are, in my view, strongly obvious; claim 1 is obvious but for the "extrusion lamination" bonding-technique limitation, which is itself obvious over the art of record (Part IV) — and which the Federal Circuit read narrowly as to structure (two layers, not mutually exclusive from extrusion coating).

IV. The "extrusion lamination" limitation — why it does not save claim 1

This is the pivotal issue, because it is the only element the six face-cited references arguably miss and it is the limitation the applicant added to get the patent allowed ("claim 1 was amended to include the disputed term in an effort to overcome a rejection based on prior art that employed a calendering process" — Fed. Cir. No. 22-2063).

1. Extrusion coating/laminating thermoplastic onto a moving web was a staple, well-known converting technique by 1999 — not a new or unpredictable technology. Extrude a molten polymer through a die onto a substrate and nip/press it with rollers: this is standard extrusion-coating line practice.
2. The prior art already pointed to it. The '482's own specification says the layers "may be affixed to the reinforcing scrim using an adhesive or any other manner of attachment" — an express invitation to substitute bonding methods.
3. The Federal Circuit's construction collapses the distinction. "Extrusion lamination" is not mutually exclusive from "extrusion coating," and both involve pressing (Lou's calendering). The district court (E.D. Tex.) construed it as "by being melted in an extruder, and forced onto the reinforcing scrim through a die of the extruder." So the claim covers ordinary extrusion coating — i.e., the very thing that was already known in the laminating art.
4. No unexpected result is attributable to the process. The applicant argued extrusion lamination yields "superior bonding," but the Board credited GAF's expert that a POSA would understand an extrusion coating that permanently bonds extrudate to substrate to be extrusion lamination. Where the asserted advantage is co-extensive with the ordinary result of a known process, KSR's "predictable results" rationale applies.

Conclusion on claim 1: even accepting the six face-cited references in isolation, the difference between them (Stokes: scrim fusion-bonded between two PVC layers; Katman: thermoplastic surface layer bonded to a reinforced base) and claim 1 is a known, predictable bonding technique, and the claim is obvious.

V. Dependent claims — routine optimization and known adjuncts

Depends from claim 1 inherit the same analysis; because claim 1 is itself obvious once the bonding technique is supplied, the dependent claims fall with it under In re Fout / the ordinary rule that a dependent claim cannot be nonobvious if its base claim is obvious and the added limitation is known.

VI. Motivation to combine — explicit rationales

For each candidate combination, an articulated reason with a rational underpinning (KSR; In re NuVasive):

Combination A — Stokes + Bay Mills (primary, targeting claims 1, 21):

• Same field, same problem: both address roofing/waterproofing membranes needing tear/puncture resistance.
• Reasonable expectation of success: Stokes already proves that a fiber scrim sandwiched in a polymer sheet yields a fluid-impervious, tear-resistant membrane; Bay Mills proves that an open over-under yarn grid is the standard reinforcing scrim for roofing membranes. Combining them is substituting one known roofing scrim for another in a known reinforced membrane architecture — a KSR "predictable use of prior art elements according to their established functions."
• Design incentive: Bay Mills expressly frames the goal as maintaining the grid in the membrane and improving strength/delamination resistance — the identical objectives the '482 states.

Combination B — Katman + Bay Mills (alternate, targeting claims 1, 21):

• Katman teaches the thermoplastic surface layer as the strength-providing member and teaches bonding a reinforcing material into it; Bay Mills supplies the roofing-membrane scrim. Motivation: get tear resistance + waterproofing in one flexible sheet that can be rolled.

Combination C — Any of A/B + Grace, JPS, or Funkhouser (context references):

• These are roofing-membrane references supplying the environment (single-ply reinforced roof membranes; reinforced waterproofing over porous/draping decks — precisely the "spaced support structures" problem the '482 specification emphasizes). Low confidence on their specific disclosures — flagged in Part II — so I treat C as contextual, not load-bearing.

Combination D (dependents): A or B in further view of (i) known woven-polypropylene anti-slip fabrics, (ii) known metalized-film/aluminum-foil radiant barriers, (iii) known micro-perforation practice. Each is a KSR "known technique to improve a similar device in the same way."

Teaching away? None identified in the face-cited art. The only candidate is generally-held industry preference for asphalt-saturated organic felts, but a mere preference for a different (and inferior) incumbent product is not a teaching away (In re Gurley requires the art to criticize, disparage, or discourage the claimed solution — the '482's own background criticizes the felt approach, not the reinforced-film approach).

Secondary considerations (objective evidence):

• The specification asserts a long-felt need — paper-based underlayments deteriorate faster than the tile overlayment and fail on spaced rafters. This is genuine narrative support for nonobviousness, but (a) the asserted nexus is to the problem, not to the claimed extrusion-lamination limitation, and (b) the record before me discloses no evidence of commercial success, licensing, copying, or industry praise offered against these references. On the available record, objective evidence would not, in my assessment, overcome a prima facie case.
• Caveat: I have not reviewed the patent owner's IPR § 42.107 response or the FWD's treatment of secondary considerations in full; those may contain evidence I have not surfaced. This is a genuine gap and I am not asserting the absence of such evidence — only its absence from what I retrieved.

VII. Ground truth — the art that actually invalidated the patent (outside the six face-cited references)

I include this because the task is a § 103 analysis of the patent as a whole, and the adjudicated answer differs from the face-cited set. Everything below is from the IPR record and the Federal Circuit opinion, not from the patent's own citation table.

• IPR2021-00192 (GAF Materials LLC, petitioner). Final Written Decision May 24, 2022 — "Determining All Challenged Claims Unpatentable, 35 U.S.C. § 318(a)." Confirmed by the docket summary at GreyB/IPVerse and by the patent's legal-events record.
• Prior art actually used: Lou (the primary reference — a process for making a coated fabric suitable as a roofing-tile underlayment, by extruding a continuous polypropylene coating onto a vapor-and-liquid-permeable base sheet of synthetic organic fibers and then calendering), plus Howells (extrusion lamination with first/second extruder nozzles simultaneously dispensing molten thermoplastic onto opposing surfaces of an open-mesh fabric; also teaches a slip-resistant layer), Ellison (reinforcing fabric with a thermoplastic layer on each side, heat-bonded), and Goodacre (Ground 1(e), claims 13/14/17). A "Peterson" reference appears in the file history (rubber-mill calendering).
• Why the Board's grounds succeeded where the examiner's citations did not: the applicant had added "by extrusion lamination" to escape a calendering-based rejection; GAF responded by (a) litigating product-by-process, then (b) proving that Lou's extrusion + calendering meets the limitation once "extrusion lamination" is construed to include pressing and to be non-exclusive from extrusion coating. The Board and the Federal Circuit agreed.
• Claim survival: the PTAB inter partes review certificate (kind code K1) issued September 11, 2024 for IPR2021-00192; secondary sources state the certificate cancelled all claims (flagged in the prior summary as lower confidence — I did not retrieve the certificate PDF myself). The Federal Circuit affirmed in Kirsch Research & Development, LLC v. GAF Materials LLC, No. 22-2063 (nonprecedential, Judge Stark, May 2, 2024), and a CAFC mandate dated September 3, 2024 appears in the PTAB record. No 2026 appellate activity surfaced.
• Related outcomes: IPR2020-01389 (Owens Corning) settled; IPR2021-01181 (Atlas) settled; IPR2021-01183 (Epilay) settled; IPR2022-00416 (IKO) institution denied (May 20, 2022). District court actions were largely stayed and resolved — e.g., Kirsch v. BlueLinx, W.D. Tex. 6:20-cv-00316, reportedly dismissed by joint Rule 41 stipulation (lower confidence; secondary commentary).

Takeaway for § 103: the six face-cited references establish a strong prima facie case that would have supported an obviousness rejection at prosecution (particularly for claims 21 and 34, and for claim 1 once extrusion coating/laminating is recognized as a known bonding technique). The examiner's citations were, however, apparently never combined in that way, and the art that ultimately carried the day was a different, more on-point set (Lou/Howells/Ellison/Goodacre). Both routes converge on the same conclusion: the claims of US 6,308,482 are obvious under § 103.

VIII. Contradictions, gaps, and confidence

No contradictions found between the previously generated sections and the source text — the previously generated summary's claims, dates, IPR outcomes, and CAFC affirmance all reconcile with the Google Patents text and the search results I retrieved. The one date anomaly it flagged (Unified Patents portal showing Mar. 14, 1999 / Mar. 14, 2000 / Oct. 29, 2001 vs. the patent's Mar. 15 / Mar. 15 / Oct. 30) recurs in my searches (the Unified Patents page lists priority 1999-03-14, grant 2001-10-29, expiration 2020-03-14) — consistent with a time-zone offset artifact; flagged, not reconciled.

Confidence:

• High: the claim-element mapping for Stokes (US 3,663,350), Bay Mills (US 5,593,766), and Katman (US 5,843,554); the motivation-to-combine rationales; the "extrusion lamination" construction (from the Federal Circuit opinion text); the IPR2021-00192 all-claims-unpatentable FWD and the No. 22-2063 affirmance; the § 102(e) status of US 5,979,133.
• Low / unverified — expressly flagged: the specific disclosures of US 4,585,682 (Grace), US 5,523,357 (JPS), and US 5,979,133 (Funkhouser). My search for these three was cut off before returning results, so I characterize them only by title/assignee/date and any inference from the field. I do not assert what they disclose. Any conclusion resting on Combination C should be re-verified against the reference texts.
• Not asserted: I found no evidence of secondary considerations in the sources I retrieved; that is a statement about my search, not a finding that none exists.
• No fabrication: prior-art reference numbers, dates, ground numbers, and the "Lou/Howells/Ellison/Goodacre" identities are taken from the retrieved IPR/CAFC material; where I could not verify a reference's content I said so rather than supplying it.

Bottom line: On the six references cited on the face of US 6,308,482, claims 21 and 34 are strongly obvious (Bay Mills' over-under reinforcing grid + Stokes' scrim-encapsulated thermoplastic sheet; micro-perforation as routine optimization of a result-effective variable), and claim 1 is obvious because the sole gap — "extrusion lamination" — is a known bonding technique that the Federal Circuit held to overlap with ordinary extrusion coating and to require no more than two layers. The dependent and other independent claims add only conventional adjuncts (slip resistance, radiant barriers, ASTM standards, polymer selection, double-sided coating). This is confirmed by the operative adjudication: all claims of the '482 patent were determined unpatentable in IPR2021-00192 using a different, even more on-point set of references, and that determination was affirmed.