Roof valley repair techniques fix problems in this critical seam area. A roof valley is where two roof surfaces come together, such as in the inside corner of a roof on an L shaped building. With asphalt shingles, this area can be covered by interweaving the shingles at this juncture, but this is somewhat complicated, so many roofers use a metal valley which is a wide v-shaped piece of flashing. Installed correctly, roofing felt is interwoven across the valley, then a sheet of ice and water shield runs down the valley. This product seals against nail punctures. The metal valley is put down after this and before the shingles.
Most roofing materials are installed starting from the bottom edge of the roof, and the next layer goes on top, moving all the way up to the ridge. This way water drains off the first top piece and flows down onto the next one, down to the gutters. On an inside corner, twice the volume of water is coming down. During large rainstorms, water from one roof can run under the shingles of the other roof.
One of the things that make you think you need to repair the valley, could be caused by buildup of plant life. People rarely look up at their roofs, but inspecting it personally, in the spring and fall, and especially after storms is a good idea. If you haven’t cleaned your gutters out and have maple trees by your house, you could have a mini garden growing in your gutters. In a valley, this can cause a mini dam to build and water behind it will go beyond the width of the valley and work its way under shingles. Roof valley repair techniques are best left to professionals, but gutter cleaning can minimize your difficulties.
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