How should I compare overlay and tear-off quotes when decking is uncertain?

The concern about an overlay hiding deck damage is the key issue. I wouldn’t reject every overlay automatically, but I would reject it if inspection finds active leaks, widespread soft or delaminated sheathing, deficient roof-to-wall or flashing details, or ventilation problems that the second layer would conceal.

For comparing the quotes, don’t use the lowest decking allowance as the expected cost. Have both contractors price the same assumed replacement quantity, then show a sensitivity range, such as 5%, 15%, and 30% of the deck, with the per-sheet labor and disposal cost stated. Add the future cost of removing both layers if the overlay is the option being considered. That makes the comparison meaningful even though the actual damage can’t be confirmed until tear-off.

The sensitivity range is useful, but the quotes should also spell out the decision process once the roof is opened:

- State who can authorize concealed-deck replacement: the owner, an on-site representative, or the contractor under a preapproved limit.
- Give the unit price for each sheet or square foot, including labor, fasteners, and disposal. Don’t rely on a vague “extra materials” clause.
- Say whether the contractor may proceed at that price without waiting for approval, so the roof isn’t left exposed while someone is deciding.
- Require photos or other documentation of the damaged areas before they’re covered, where weather and site conditions allow.
- Identify any work that requires a separate written change order, especially structural repairs rather than ordinary sheathing replacement.

That authorization language matters more with an overlay quote, since it may defer discovery and make the later tear-off decision harder to price fairly.

The quotes should define the evidence required for deck replacement, not just the authorization process.

Distinguish structural deterioration, delamination, unsafe deflection, or sheathing that cannot hold the specified fasteners from cosmetic staining or an isolated minor defect. The contractor should document the location and extent, but “damaged” should not become a blanket reason to replace otherwise serviceable panels. A written unit price is most useful when paired with an agreed replacement criterion, so an overlay and a tear-off are compared on the same basis.

An agreed replacement criterion is useful, but it will not resolve every concealed-deck dispute.

- It works for clear cases, such as delamination, unsafe deflection, or panels that will not hold the specified fasteners.
- If the disagreement involves structural capacity, framing support, or fastening integrity rather than an individual panel, the contract should identify an independent inspector or structural engineer as the decision-maker.
- It should also state who pays for that evaluation and how authorization will be handled if weather protection cannot wait for a written finding.
- Photos and unit prices still help, but they do not replace an independent opinion when the question is load capacity rather than visible damage.

That keeps a structural concern from being treated as ordinary sheet replacement, while avoiding automatic replacement based only on staining or a vague “damaged deck” description.