Roof Leaking On Underside Plywood

At the intersection of the plywood overlays the upper sheets contain black mold spreading about 2 3 up the slope.

Roof leaking on underside plywood.

Often water runs to openings in the vapor barrier such as at ceiling light fixtures. From the outsidethere are a couple of dips in the plywood which appear as though thes areas were loaded with shingles during re roof. Locate the source of the leak by examining the underside of the roof from within your attic or crawl space. Look for damp spots on the underside of your roof.

On structural concrete and possibly wood planks or plywood moisture drips may not be observed. Mold on the underside of roof sheathing is also very common. If your roof is leaking right now go into the attic with a flashlight and some chalk to mark with while it s raining. Unless the roof is leaking the line you see on the roof is an aesthetic problem but the cupped plywood is putting an added strain on the shingles either side of the visible line.

Roof cuts and thermographic imaging can also detect moisture in addition to other strategies. Rotted plywood cannot support the weight of a roof the way healthy wood can nor can it safely grip the nails put into the roof and keep them held firm. Some roof leaks are tough to locate. It also dips along the edge where the moldy plywood exists.

Also look for a thin stream of water flowing down one of the rafters. Cracking noises can sometimes be heard when walking on the roof during wintertime as a thin layer of ice breaks he adds. Mold that grows on the underside of roof sheathing due to ideal mold growth conditions being present. If your ceiling has a plastic vapor barrier between the drywall and the attic insulation push the insulation aside and look for flow stains on the plastic.

Trowel the roofing tar into the leak on the underside of the roof deck using a putty knife. Sometimes the water shows up at a ceiling spot distant from the leak. Push the shingle or plywood into the tar and trowel more roofing tar around the edges of the patch. Step 2 shine a flashlight along the underside of the roof and look for a hole in the roof as well as areas that are wet or have been darkened by moisture.