OSB resistance to pooled water?

[Default User]

There is a spec house going up in the phase II part of our sub. We've gotten a torrential downpour, a real monsoon, last weekend. The roof on this spec was only papered at the time, although the walls were sheathed and house wrap plus windows and doors installed.

The 23/32" OSB decking for the subfloor has water standing on it almost throughout the entire house, and the roof decking also showed signs of being wet.

They roofed it this week (closed the barn door after horses are out).

Was wondering how this would effect the floor, the OSB soaking in pools of water for a couple days?

[marson]

most OSB is rated "exposure 1" which means it can withstand the moisture it will inevitably encounter during the construction process. might have some flakes come up and some edge swelling, but these are not big problems.

i've seen roof sheathing that went through multiple rainstorms that exhibited edge swelling. the builder put on very cheap three tab shingles and in the right light you could see the outline of the sheets on the roof. this might have been because the carpenters didn't gap the sheets 1/8" too.

i used to worry a lot more about rain on my subfloors until i built a very complicated structure that we started framing in march and dried in in october...plywood turned black, but it was still fine. worst part about getting the frame that wet is that you might have nail pops in your sheetrock from wood movement.

[Jonny]

After they lay the felt on the roof, its considered "dried in". Guessing the rainwater was windblown under the felt. Perhaps even torn by the wind. The subfloor should have gotten minimum water, if any, with the wall exterior cladding, windows and doors installed. Standing water is a problem with OSB. You will recognize it when the OSB starts a circular bubble or two on the surface. As opposed to plywood, where the surface raises or bubbles up in relation to the grain pattern.

If they just laid the shingles over torn felt, you're looking at potential leaks down the line.

[Bobk207]

I'm surprised that much water got INTO the house.

If the building paper was intact, I wouldn't worry too much about the roof sheathing but I would have delayed roofing if no more rain was expected for a while.

Roofing immediately after rain is a good way to trap extra moisture in the strucuture.

The floor deck is another issue....days of standing water on OSD is not a great thing. They should have vacuumed up the standing water ASAP & ventilated the house with fans / gas fired heaters.

cheers Bob

[amfe]

Hi

I have a major in industrial engineering but have always worked with game and 2 minor jobs in construction. I was looking for advise as to a software that could help me design and build homes with mexican standards ( rebar, cement and brick).

thanks alfredo

[Jonny]

If you note, the OP never gave an approximate verbatim weight or mass of water. Probably intentional.

The owner can't delay the roofing subcontractor, only the contractor can do that. By the time its implemented, its too late.

Again, the amount of water is the key. Unless the joists of the subfloor are contributing dramatically to standing water on the subfloor decking, the actual amount of water is probably minimal.

Am still waiting for something more descriptive and with weighted values regarding standing water. Along those lines, wind damage to the roof underlayment description. All is left to the reader's imagination.