When you get a new asphalt shingle roof put on, your contractor will probably put down new underlayment too. Underlayment is a barrier that goes on top of the deck and under the shingles. Here's a look at the purpose of underlayment and how a residential roofing contractor might apply it.
Why Your Roof Needs Underlayment
Underlayment is a thin sheet of felt paper or plastic that acts as a water barrier for your roof. If one of the new asphalt shingles is torn off by the wind, the underlayment is exposed, but the deck is covered. The underlayment will keep rain from getting on the roof deck. When all the old shingles are removed, the deck is vulnerable if an unexpected rain pops up. However, as long as the underlayment is down, your deck will be safe and protected until the residential roofing contractor gets the new shingles in place.
The thin sheet of plastic also creates a smooth surface on your deck for attaching the new shingles and for keeping bugs and dust from getting into your attic.
How Underlayment Is Applied
Your roofing contractor might choose a type of underlayment that attaches with a peel-and-stick backing. This eliminates the need to use nails that create holes that could potentially leak in the future. However, the material can also be attached with staples or cap nails.
The installation method might be determined by the slope of your roof or local building codes to ensure the material stays put if shingles are blown off in high winds. Underlayment is cut to size and spread out over the deck to provide uniform coverage and protection from the rain.
Underlayment can also be cut into small patches and used to repair old material that has worn out due to sun exposure or raccoon damage. When your roofer repairs or replaces old shingles, they also check the underlayment. If the underlayment under the bad shingles is damaged, new underlayment can be patched in before the new shingles are applied.
When a residential roofing contractor gives you a quote for your new roof, the type of underlayment and its cost are included. It's a common roofing material that's not only used for asphalt shingle roofs, but for metal and clay tile roofing too.
Underlayment may not last as long as roofing shingles, especially if it's exposed by a missing shingle. That's one reason it's important to get quick roof repairs. If the underlayment wears down, the deck of your roof is at risk of getting wet and water damaged.