Replacing an Old Cedar Shake Roof in Austin: Options, Wildfire Code and What Is Underneath
| # | Table of Contents |
|---|---|
| 1 | Signs a Shake Roof Is Done |
| 2 | What Is Under the Shakes |
| 3 | Your Replacement Options |
| 4 | The Wildfire Code and Class A |
| 5 | Permits in Austin |
| 6 | Planning the Job |
| 7 | FAQ |
Signs a Shake Roof Is Done
Cedar shake roofs are found on many older homes in and around Austin. When they reach the end of their life, the signs are usually easy to see from the ground or a ladder:
- Shakes that are split, cupped, curled or noticeably thinner than they used to be.
- Missing shakes, or gaps where you can see the felt or boards underneath.
- Moss, lichen or dark, soft areas that stay damp after rain.
- Repeated repairs in the same areas, or interior stains below the roof.
- Shakes that crumble or break when touched during a repair.
Once a shake roof is widely worn, patching one area at a time rarely holds. Replacement also gives you the chance to fix ventilation, flashing and decking problems that have built up underneath.
What Is Under the Shakes
Wood shakes are allowed by the International Residential Code over solid sheathing or over spaced lumber sheathing: boards nailed across the rafters with gaps between them, spaced to match the shake exposure. Many older shake roofs were built this way.
That matters because most replacement materials need a solid deck. The 2024 IRC, which the City of Austin enforces, says "asphalt shingles shall be fastened to wood structural panels or solid lumber sheathing." So when shakes come off a spaced-board roof and shingles go on, the roof typically needs new plywood or OSB decking over the old boards, or in place of them. Your contractor should tell you up front how the existing deck was built and what their quote includes for it.
The code also sets a minimum slope for wood shakes of 3 units vertical in 12 horizontal, so low-slope sections such as porch roofs may need a different material regardless.
Your Replacement Options
| Option | Deck | What to know |
|---|---|---|
| Asphalt shingles | Solid deck required | New sheathing over or in place of spaced boards. Full tear-off of the shakes. |
| Metal (standing seam or metal shingle) | Depends on system | The 2024 IRC allows metal over existing wood shakes if the shakes are first covered with an approved fire-protective layer. Tear-off is still the usual approach. |
| Concrete or clay tile | Depends on system | Same code allowance over shakes as metal. Tile is heavy, so ask whether the framing needs to be checked for the added weight. |
| New wood shakes | Solid or spaced | In the WUI area, only as part of a tested Class A assembly (see below). Confirm insurability with your carrier before choosing. |
The code allowance for metal and tile over shakes, section R908.4, comes with a condition in R908.4.1: where the new roof "creates a combustible concealed space," the whole existing surface must first be covered with gypsum board, mineral fiber, glass fiber or another approved material. Tearing off the shakes instead lets the deck, flashing and ventilation be inspected and corrected before the new roof goes on. See our metal roofing page if you are considering metal.
The Wildfire Code and Class A
Austin adopted the 2024 Wildland-Urban Interface Code for work starting on or after July 10, 2025. If your home is in the WUI area, the City's code page states: "A Class A roof assembly is required. This is the highest fire rating for a roof assembly or covering." It defines the assembly as the covering, deck and underlayment or insulation, "all tested together for fire resistance." The same page says replacing 50% or more of the roof "requires full replacement" to WUI standards.
Untreated cedar is not a Class A covering. Fire-retardant-treated shakes exist, but the treatment alone is not enough. One ICC-ES evaluation report for treated cedar shakes (ESR-1410, reissued June 2026) lists the treated product as Class B and allows it on roofs requiring Class A only when installed over a specific fire-resistant layer, such as a listed roof board or a mineral-surfaced cap sheet, as a tested assembly. If you want a wood look in the WUI area, ask for the exact listed Class A assembly in writing and confirm it with the City.
You can look up your address on the City's Interactive WUI Code Map, linked from the Wildland-Urban Interface Code page.
Permits in Austin
Inside the City of Austin, replacing a roof covering that does not affect the roof structure is on the permit-exempt list, except in the WUI area when 50% or more of the roofing is replaced. The exemption for roof decking only covers up to 128 square feet. Re-decking a whole spaced-board roof goes well past that, so ask your contractor whether your job needs a permit before work starts. Our guide to roof replacement permits in Austin walks through the rules. Outside the city limits, check with your own city or county.
Planning the Job
- Confirm whether your address is in the WUI area.
- Ask how the existing deck is built and how new decking is priced.
- Choose a material that meets the fire rating your address requires.
- Ask about permits, and who pulls them.
- Plan for ventilation, flashing and gutters to be addressed while the roof is open.
Our roof replacement team can inspect your shake roof, check what is underneath, and give you a written scope for each option so you can compare them on the same terms.
Sources: 2024 International Residential Code sections R902.1, R905.2.1, R905.8.1, R905.8.2, R908.3, R908.4 and R908.4.1; City of Austin, Wildland-Urban Interface Code page and Work Exempt from Building Permits page; ICC-ES Evaluation Report ESR-1410 (reissued June 2026).
Frequently Asked Questions
Can you put shingles over a cedar shake roof?
Not as a simple overlay. The 2024 IRC requires asphalt shingles to be fastened to wood structural panels or solid lumber sheathing, and shake roofs are often built on spaced boards. The shakes typically come off and a solid deck goes on before shingles.
Can metal roofing go over wood shakes?
The 2024 IRC allows metal and tile over existing wood shakes if the shakes are first covered with an approved material such as gypsum board, mineral fiber or glass fiber where a combustible concealed space would be created. Tearing off instead lets the deck be inspected.
Are wood shakes allowed in Austin’s wildfire (WUI) area?
The City requires a Class A roof assembly in the WUI area. Untreated shakes do not meet that. Treated shakes can be part of a Class A assembly only when installed over a specific tested fire-resistant layer, so ask for the listed assembly in writing.
Do I need a permit to replace a shake roof in Austin?
Replacing a roof covering that does not affect the structure is permit-exempt in the City of Austin, except in the WUI area at 50% or more. Decking replacement over 128 square feet is not exempt, which often applies to shake roofs on spaced boards. Confirm with your contractor or the City.
How do I know if my shake roof has spaced sheathing?
From the attic, you may see boards with gaps between them and the underside of the shakes or felt showing through. A roofer can confirm during an inspection.
