Roof Leaking On Underside Plywood

Often water runs to openings in the vapor barrier such as at ceiling light fixtures.

Roof leaking on underside plywood.

The presence of mold in your attic is often the result of poor ventilation insufficient insulation moisture from a roof leak or improper venting from your bathrooms or kitchen. At the intersection of the plywood overlays the upper sheets contain black mold spreading about 2 3 up the slope. 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. Cracking noises can sometimes be heard when walking on the roof during wintertime as a thin layer of ice breaks he adds.

Look for damp spots on the underside of your roof. 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. Locate the source of the leak by examining the underside of the roof from within your attic or crawl space.

Sometimes the water shows up at a ceiling spot distant from the leak. Moisture causes wood to rot and rotten wood absorbs water even more readily than fresh wood. It also dips along the edge where the moldy plywood exists. Push the shingle or plywood into the tar and trowel more roofing tar around the edges of the patch.

Roof cuts and thermographic imaging can also detect moisture in addition to other strategies. 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. Mold on the underside of roof sheathing is also very common.

From the outsidethere are a couple of dips in the plywood which appear as though thes areas were loaded with shingles during re roof. Mold that grows on the underside of roof sheathing due to ideal mold growth conditions being present. Also look for a thin stream of water flowing down one of the rafters. 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.