Rain soaked the subfloor before the roof was dried in. What to check before you close it up

Weyerhaeuser backs Edge Gold with a limited warranty against delamination and a 200-day no-sand limited warranty. APA, the engineered wood trade group, says such panels tolerate limited wetting during construction delays and stresses the word limited: cover them as soon as practicable. When OSB does swell, Weyerhaeuser's technical support says it shows mostly at the 4-foot panel ends, where neighboring sheets can push into each other and raise a ridge. The swelling often shrinks as the wood dries.

Getting underlayment on the roof now is the right move. The question is what happens after. APA says that once the shell is closed, roof and wall sheathing and framing should dry to under 18% moisture before wall or roof cavities are enclosed or finishes go in. It also warns that low-permeance insulation sprayed under a roof deck, paired with a vapor-tight layer on top such as some adhered shingle underlayments, sharply cuts the deck's ability to dry.

Measure before flooring. APA's subfloor note tells builders to confirm a wet subfloor has dried using a calibrated hand-held meter, since readings vary with panel and meter type. Weyerhaeuser wants panels no more than 4 points above the flooring's expected in-service moisture, which it puts at 8 to 12% near the coasts, 6 to 10% inland and 5 to 9% in dry regions. For planks 3 inches and wider, panel and flooring should be within 2 points. APA says decay and mold become a risk when wood stays at roughly 20 to 25% for long periods.

Sweep standing water off and pump out the basement. Hold off on sanding: Weyerhaeuser says to sand ridges only after the panels dry, ideally with the roof and windows in and the HVAC running, and APA specifies a heavy-duty floor sander before hardwood goes down. Walk the floor for squeaks and loose panels and refasten them.