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Weatherproof an asphalt roof with roof flashing

Along with the underlayment, you'll also need to weatherproof an asphalt roof with roof flashing to deal with valleys between roof peaks and the edges of chimneys.

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Weatherproof an asphalt roof with roof flashingA roof covered with asphalt shingles atop a layer of underlayment can resist most moisture. Along with the underlayment, you'll also need to weatherproof an asphalt roof with roof flashing to deal with valleys between roof peaks and the edges of chimneys. The combination of the three materials should prevent moisture from seeping through the roof decking, even during strong storms consisting of driving rain or snow.

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Before you can begin to weatherproof an asphalt roof with roof flashing, you must first lay a weatherproofing membrane over the roof decking. This membrane is known as underlayment, and can be formed from a variety of materials from builder's felt to rubber.

The underlayment is unrolled across the wooden roof decking in overlapping rows, with the overlapping areas arranged so the top of the overlap strip is higher toward the roof's peak than the lower strip. This keeps water flowing down the roof's slope without seeping between the rows of underlayment. The underlayment is stapled or nailed into place, with the edges of the material cut to run down the centers of any of the roof's valleys that run between peak areas.

With the underlayment covering the roof deck, you can begin to weatherproof an asphalt roof with roof flashing. Flashing is a thin metal strip of material fashioned into a shallow V shape that fits along the valleys of your rooftop.

When placed over the underlayment, the flashing helps to direct water down the slope of the rooftop and off its side, preventing water from seeping into the edges of the underlayment running down the center of the valleys.

The metal flashing should be cut along the drip edges at the bottom of the valley and along the top of the slope using tin snips. After cutting the flashing to fit, it can then be nailed into place along the edges running the length of the strip.

When you weatherproof an asphalt roof with roof flashing, you should also apply chimney flashing along the bases of your chimneys to prevent water from seeping beneath the underlayment as well. The process is similar to installing the flashing down the valleys of the roof; only the chimney flashing surrounds the base of the chimney and runs up the side of the object slightly. The base should then be secured with nails.

Asphalt roofing is one of the easiest roofing materials to install, but knowing how to install roof flashing is no reason to tackle the job yourself. For the best results, use a roofing contractor to ensure the process is done correctly and meets all roofing warranty requirements for the materials used.

A residential roofing contractor will be able to give you an estimate for the cost of your asphalt roof that includes the roofing prices for materials as well as the roofing cost for labor. 

When you weatherproof an asphalt roof with roof flashing, you'll help to extend the life of the roof. With underlayment, flashing and shingles in place, an asphalt roof can last for decades, protecting your home from weather damage while increasing its curbside appeal in the process.

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Photo credit: bluebirdconstruction.com