Roof Sheathing Getting Wet

If you ve ever built or had a house built in a wet area of the country you know that traditional plywood or osb can swell when it gets wet.

Roof sheathing getting wet.

Although plywood is usually more expensive than osb plywood is more resistant to moisture damage. The osb and in fact any wood panels must be allowed to dry completely depending on how wet the panels are this could be a few days before any roofing material is applied to avoid trapping moisture under the roof material that could cause edge swell and buckling. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the. If you live in an especially rainy or humid climate consider using plywood sheathing instead of osb.

It is never a good idea to install a roof over wet plywood or any type of roof sheathing. What makes this product really amazing is its resistance to water. Once your house is under roof and there s little chance of the lumber getting wet you may want to do some first aid and. I used 5 8 tongue and groove nailed for the roof.

Here are the four main ways you get wet framing lumber to dry. As the other comment said with normal exterior rated plywood one wetting assuming your attic is well enough ventilated to dry the wood out in a few days is probably not going to cause much damage to the sheathing. Mold growth on attic roof sheathing is a common issue in cool climates such as the pacific northwest. Mold on attic sheathing.

Having wet sheathing covered with tarpaper or membrane will trap the water in the sheathing very bad practice and contrary to industry standardss for roofing. Plywood can even delaminate and literally come apart at the seams. The water repellent prevented swelling of plywood and untreated osb. The ventilation is needed not only for moisture control but also to reduce by 20 40 high summertime attic and roof sheathing temperatures which are bad for roof trusses rafters and the roof sheathing as well as the shingles and underlying waterproofing membrane which can reach 160 180 degrees over an unventilated attic.