Would A Roof Sag If Plywood Got Wet

Dwight barnett answers home improvement questions.

Would a roof sag if plywood got wet.

With the shingles on it sill still breathe. Soaking wet roof decking osb roof sheathing gets rained on all the time up here and roofs are the first cover to go on a framed structure. 15 and 30 felts will breathe. The roof was put on in late 1997 so it isn t very old at all.

When rain water comes through your roof s shingles the plywood will wrap rot or weaken and this will make the roof look like it is sagging between its rafters. Roof problems may have started with wet plywood originally published april 28 2012 at 5 00 am updated april 28 2012 at 7 01 am home fix. Remedies for a sagging roof there are a number of remedies for traditional rafter style roof frames depending on the problem and its severity. I haven t had any problems and the house is 40 years old but it bothers me when i walk on the roof and feel the roof sag under my weight.

Roofs are framed with rafters or trusses which are rafters joined by internal braces so they install as a single component. Also there don t seem to be any sags or dips on the east facing side of the roof or if there are they are much smaller and barely noticable. Some problems relating to a sagging roof line should definitely be evaluated by a professional in the roofing industry. Plywood can get wet over short periods of time and be dried out and still maintain its strength and finish.

I am thinking of having an additional layer of plywood or osb added to the roof. This raises a question can plywood get wet. Often the framing can be bolstered and beefed up internally but if the roofing material needs replacement anyway it may be best to tear off the old sheathing and install larger rafters while the roof. Also with that amount of rain plywood and osb may have some swelling at the edges and a thorough inspection of the panels should be done after the panels have completely dried.

When the sun shines it dries. It is possible that the top side was wet when they put the roofing materials on and over time the wood got soft and sagged. The underside will breathe. Address any edges that are of concern to make the roof level and flat before installing the finished roof material but this should not be done until the panels have.

The minimum plywood for roofing. Rafters run from the peak of the roof. My neighbor had an additional 3 8 layer of plywood added.