There's more going on under your roof than you might expect. While the roofing material gets most of the attention, it's only the most visible part of a much deeper roofing system. The typical residential roof consists of a plywood deck, underlayment, top material (shingles, wood shake, etc.), and a final layer of flashing around vulnerable areas. Your choice of material will affect many aspects of your roof, including its appearance and durability, but the underlayment helps this material reach its true potential. Problems with your underlayment can reduce the life span of your new roof, cause damage to your decking, or lead to maintenance and repair issues. As a result, it's critical to understand how underlayments work and why you need them.

Why Roofs Need Multiple Layers

Your roof is a critical part of your home's envelope, which means it helps to create a barrier between the outside and the inside. However, the typical residential home's roof isn't genuinely waterproof. Instead, the layers of your roofing help direct water away from vulnerable areas, allowing it to drain off your roof instead of leaking into your attic. The top layer of the roof, such as asphalt shingles, do most of the heavy lifting. This material keeps most of the water out, while the flashing prevents moisture from seeping underneath. Unfortunately, some conditions may allow small amounts of water to infiltrate under this layer. For example, heavy winds can sometimes drive rainwater under shingles. Ice dams are another potential source of backed-up water.

How Underlayments Help Protect Your Home

Underlayments sit underneath your roofing material and provide a second layer of protection for harsh conditions. Even relatively small amounts of moisture can damage your roof decking, leading to rot and other problems that can reduce your roof's life span or force you to make expensive repairs. Underlayments prevent minor amounts of water intrusion from causing these problems. Typical residential homes use asphalt or synthetic felt underlayments. These materials are relatively waterproof and durable, providing the extra layer of protection your roof needs to last for as long as possible. Using a high-quality underlayment during roof installation is critical to prevent problems that may cause your roof to fail prematurely.

What You Can Do to Get Even More Protection

Standard underlayment will provide excellent protection against the elements, but you can still do more if you're installing a new roof on your home. Ice and water barriers are more advanced underlayments that offer proper waterproofing. You typically don't install these more expensive membranes across your entire roof but instead use them in areas that may be vulnerable to moisture damage.

Ultimately, a proper installation that uses high-quality underlayment is the best way to ensure your roof will last for many years. If you want even more protection against harsh weather conditions, an ice and water shield may be an option worth considering.

For more information, contact a roofer, such as Travis Smith Roofing.