When a Denver home goes from wood shingles or shakes to asphalt, expect more than a material swap. The spaced boards under most wood roofs usually need new sheathing to meet Denver’s decking rules, wall and headwall flashing often has to be replaced and counterflashed, the thinner shingles can leave a visible gap below the siding, and the attic usually needs new ventilation. Rotted trim found along the way is a separate carpentry cost. Knowing this up front keeps the bid honest and the budget steady.
Decking: what Denver requires
Wood roofs are often nailed to 1x boards spaced several inches apart so the shakes can breathe. Shingles need a solid surface. The City and County of Denver’s Roofing Guide and Checklist (updated 4/11/2024) says:
- No continuous opening between boards may be greater than 1/2 inch, regardless of the manufacturer’s recommendation.
- On 1x board decking for asphalt shingles, no opening may be larger than 6 square inches; smaller openings can be covered with 26-gauge metal.
- Existing roofs must be torn off to the deck where two or more layers of any roof covering exist.
In practice that means new plywood or OSB over spaced boards. Older homes that were added onto over the years sometimes hide different framing under each section, which is one reason we look in the attic before quoting.
Flashing: what changes at walls
| Spot | What we look at | What Denver’s checklist requires |
|---|---|---|
| Sidewalls (roof slopes up along a wall) | Old 4x5 or bent flashing set for shakes | Step flashing at least 4 x 4 inches, one piece per shingle, counterflashed and sealed |
| End of a sidewall | Water running into the wall | A kick-out that turns water away from the wall onto the roof or into a gutter |
| Headwalls (wall across the top of a slope) | Bent flashing tucked under siding | At least 4 x 4 inches, counterflashed with metal or the exterior finish |
| Stucco and brick | Old flashing buried in the finish | Counterflashing over new flashing |
Reusing sound flashing can avoid opening siding or stucco. Replacing it means removing at least one course of siding, which then needs to be refastened, caulked and painted. Paint from the original can rarely matches sun-faded siding exactly, so plan for painting the whole wall section. We tell you which flashings we plan to reuse before the job starts.
The gap below the siding
A wood shake can be more than an inch thick; an asphalt shingle is a fraction of an inch. Where the roof meets a wall, that difference leaves a band of flashing showing between the shingles and the bottom of the siding, sometimes up to two inches. It is cosmetic. Paint can blend it, or the trim can be adjusted when the flashing is replaced.
Ventilation
Shakes on spaced boards let the attic breathe; shingles on solid sheathing do not. Denver does not inspect venting on reroofs, but its checklist allows venting to be added to meet the shingle manufacturer’s requirements, and skipping it invites condensation and ice dams. We explain why in cedar shake to asphalt requires roof vents, and where ice and water membrane belongs in do Denver roofs need ice and water shield?
Hidden costs to plan for
- Rotted trim, fascia or siding found when flashing comes off. Pre-existing and usually the homeowner’s cost; we show you before we fix it.
- Decking surprises on additions or very old homes.
- Painting walls where siding was removed.
- Dust in the attic and garage. Wood roofs shed a lot of debris during tear-off, so cover stored items.
Why wood is coming off
Wood roofs are combustible, and Colorado’s Wildfire Resiliency Code requires Class A roofing in mapped wildfire areas. Several Denver-area cities have their own rules; see Denver cedar roofing and cedar shake fire hazards. If you love the wood look, weathered wood and driftwood tones like the ones below keep the warmth without the wood.
Get a Denver wood roof replacement quote
Integrity Roofing and Painting is veteran-owned and family-run since 1990, an Owens Corning Platinum Preferred contractor with 650+ Google reviews, with a Denver-area office at 13275 E. Fremont Pl in Centennial. We pull the Denver permit and walk you through decking, flashing and venting before you sign. Call (303) 209-0152, book a free Denver roof inspection, or see Denver roof replacement.
Sources: City and County of Denver, Roofing Guide and Checklist (updated 4/11/2024); Colorado Division of Fire Prevention and Control, Colorado Wildfire Resiliency Code.
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