(214) 807-0414Request an assessmentDecking guide
The deck stays hidden right up until the moment tear-off exposes it, which is the whole problem with pricing it. Decking is the structural surface everything else fastens to, and its condition is the one major variable in a replacement that cannot be settled before the work starts. That is why it appears as an allowance instead of a fixed figure.
In short
Plywood is cross-laminated veneer. OSB is compressed strands. Both are ordinary roof sheathing. The practical difference shows at the panel edges: OSB swells when repeatedly wet and tends to stay swollen, while plywood is more likely to dry back toward its original thickness.
01
A responsible estimate states a unit price per sheet, the quantity assumed in the base scope, and how anything beyond that gets authorised and documented before it is installed. That is not vagueness. It is the honest way to price something nobody has seen. An open-ended decking line with no unit price attached is the version to question.
02
Eaves and edges, valleys, around penetrations and beneath previously repaired areas. Those are where water concentrates and where an earlier leak spent its time. A deck can be sound across the whole field and unusable in the last two feet above the gutter.
03
Shingles stay on the roof through fasteners set in sound sheathing. A nail driven into a delaminated panel, or into the gap between two of them, is holding nothing. Deck condition tends to show up later as wind performance rather than as a leak.
Questions
Ask for dated photographs of each replaced area before the new sheathing is covered, with a count that matches the invoice. Deck replacement is among the easiest lines on a roofing invoice to inflate and among the easiest to document honestly.
Yes. Sheathing is replaced panel by panel where it is unsound. Full replacement is a different decision, driven by extent or by a structural problem rather than by convenience.
Nobody sees it. That is the substantive objection to covering one roof with another, more than the weight or the finished appearance: the sheathing, the fasteners and any damage left by an earlier leak stay hidden under two layers instead of one, and whoever opens it next deals with all of it at once. It also passes up the only moment when repairing the deck is straightforward and cheap.
That is a different thing from replacing unsound panels and it does not substitute for it. Overlaying a whole deck adds height at the edges and at every penetration, changes the fastener length the covering needs, and leaves whatever was underneath still underneath. It is occasionally specified for a real reason. Offered as a way to avoid finding out what the existing panels are like, it is the wrong answer.
Usually no. Sheathing is the panel surface the covering fastens to; the rafters or trusses beneath it are the structure. A few soft sheets at an eave is a water problem that stayed local, and replacing them is ordinary work. Sagging between rafters, a ridge line that has gone out of straight, or a deck that moves underfoot across a wide area is a different conversation, and it belongs to a structural engineer rather than to a roofing crew.
Assessment request
Short, routing-only questions. Nothing here asks you to diagnose the roof yourself.