The roof deck — the plywood or OSB beneath the underlayment — is the layer you cannot see and the layer that determines whether the rest of the roof is built on a sound substrate. During a re-roof, the deck is briefly exposed and is the moment a roofer either does the necessary work or pretends it does not need doing.
What gets done at the deck is the work that distinguishes a serious re-roof from a hasty one.
What should happen at the deck
Inspection of every panel
Each sheet of plywood or OSB on the roof is inspected. The inspection looks for:
- Rot or water damage
- Delamination between plies
- Soft spots that indicate failed adhesive
- Holes or damage from prior work
- Spans that exceed code (older homes may have undersized decking)
Repair or replacement of damaged sections
Any deck panel that fails inspection is replaced. The replacement is the same gauge plywood (typically 15/32" / "1/2-inch") or OSB, matched to the existing surrounding deck.
Re-nailing to current code
The entire deck is brought to current attachment specification — 8d ring-shank nails at the code-prescribed pattern for the wind zone. Most pre-2007 homes have less than current pattern.
Documentation
Photographs of any deck repair, with notes documenting the location and extent. This is the proof that the deck work was done; without it, the work cannot be verified.
What sometimes happens instead
Visual inspection from atop the underlayment
The roofer installs underlayment over the existing deck without close inspection. Any deck issues are hidden under the new material until they become visible problems years later.
Repair only of obviously visible damage
The roofer addresses the deck issues that are obvious during tear-off but does not pursue the less obvious ones. The repair is partial; the underlying issues remain.
Skipped re-nailing
The existing nail pattern is left as-is. The wind-mitigation report cannot claim the higher discount; the deck attachment performance is below current code.
No documentation
Whatever work was done at the deck is not photographed. The closeout package cannot confirm the work; the homeowner has no proof.
How to tell the difference
Three checks during your re-roof:
1. Ask to see deck photos during tear-off
The roofer should be photographing the deck at the moment the existing roof comes off. Ask to see these photos in real time, not at closeout.
2. Ask about re-nailing specifically
The roofer should be able to tell you the exact attachment pattern they will install (e.g., "8d ring-shank at 4"/6" for your HVHZ zone"). If the answer is general, the work may be general.
3. Verify in the closeout package
The closeout should include before-and-after deck photos, documentation of any repairs, and confirmation of the final attachment pattern.
What deck quality is worth
The cost premium for thorough deck work on a typical 4,000-sq-ft re-roof:
- Repair of damaged sections: $1,500-$5,000 depending on extent
- Re-nailing to current code: $1,200-$2,400
- Documentation labor: included in the project overhead
Total: $2,700-$7,400 of work that distinguishes thorough re-roof from hasty re-roof.
What this earns:
- Higher wind-mitigation discount on insurance (typically $300-$700 annually)
- Significantly better storm performance
- 25-50 additional years of usable deck before next replacement
- Documentation that supports insurance and resale conversations
Where we differ
Two things we do that not every roofer does:
We bid the deck work as a separate line item
The cost of deck repair and re-nailing is itemized in our bids, with an allowance for typical repair quantities and a contingency for unusual conditions. Owners can see what is being spent on deck work as a component of the project total.
We refuse to leave inadequate deck in place
If the deck inspection reveals damage that is not in the allowance, we have the conversation with the owner about expanding the scope. We do not cover failed decking with new underlayment and proceed.
The conversation can be uncomfortable mid-project. The alternative — covering bad decking and walking away — is worse. We have been the third roofer called to a project where the previous roofer did exactly that, and the cleanup is substantially harder than the original work would have been.
The deck is the foundation of the roof. The roofer's treatment of it is the foundation of the project.
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