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One question that people often ask is whether or not an underlayment is required beneath asphalt shingles. In general, it’s a good idea to use underlayment under any type of roofing, including shingles. But, the answer to this question is a little bit murky, so let’s take a deeper look!

Do You Need Underlayment?

The answer is both yes and no. Technically, no, underlayment isn’t 100% necessary underneath asphalt shingles. At least, not in areas unregulated by code! Building codes vary from one region to the next, and most all building codes require felt or synthetic roofing underlayment. So if you’re working in an area where building codes do apply, then yes, shingle underlayment will almost certainly be required.

No Underlayment is Likely to Void the Warranty

Shingle roofs are generally backed by a manufacturer’s warranty, but in order for that warranty to be valid, the manufacturer is likely to require certain conditions to be met. This includes things like approved fastener types and also a shingle underlayment that meets the specifications set forth by the manufacturer. This is important for homeowners because should something happen to those shingles, they’ll want that warranty to cover repairs or replacement!

Required or Not, Underlayment is the Smart Choice

Whether or not underlayment is required, it’s always a good idea because it provides the roof deck an extra layer of defense against damage. There are all kinds of issues that can beset a roof over time. Storms and high winds can drive rain beneath shingles. Without underlayment, this rain will soak into the roof deck and cause problems ranging from mold and rot to leaks within the home’s interior. Snow sitting on roofs and the ice dams that form along a roof’s edge can also allow water to seep beneath shingles.

Underlayment exists to protect the deck so that if moisture does get past the primary roofing material, the underlayment can stop it from damaging the deck. While it is an additional cost, it will also save money by preventing water damage to the wood beneath. Even if not always required by local building codes, underlayment should be a key part of every roofing system.