R906 Roof Insulation — 2025 California Residential Code
California Residential Code (Title 24, Part 2.5) · 2025 edition · updated 2026-09-26 · California
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Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Residential Code (Title 24, Part 2.5) § R906 · Effective January 1, 2026 · Official source: Building Standards Commission
R906.1 General.¶
Where above-deck thermal insulation is installed, such insulation shall be covered with an approved roof covering and shall comply with NFPA 276 or UL 1256.
R906.2 Material standards.¶
Above-deck thermal insulation board shall comply with the standards in Table R906.2.
TABLE R906.2—MATERIAL STANDARDS FOR ROOF INSULATION
| MATERIAL | STANDARD |
|---|---|
| Cellular glass board | ASTM C552or ASTM C1902 |
| Composite boards | ASTM C1289, Type III, IV, V or VI |
| Expanded polystyrene | ASTM C578 |
| Extruded polystyrene board | ASTM C578 |
| Fiber-reinforced gypsum board | ASTM C1278 |
| Glass-faced gypsum board | ASTM C1177 |
| Mineral wool board | ASTM C726 |
| Perlite board | ASTM C728 |
| Polyisocyanurate board | ASTM C1289, Type I or II |
| Wood fiberboard | ASTM C208 |
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