Synthetic Underlayment Installation for Residential Roofing

When it comes to roofing your home in Gainesville or nearby towns like Buford, Flowery Branch, or Cumming, one decision that often gets overlooked—but shouldn’t—is your roofing underlayment.

At L&L Roofing & Construction, we believe in doing the right thing, even in the details you don’t see. That’s why we trust synthetic underlayment as a reliable, durable layer of protection for your home.

Why Use Synthetic Underlayment?

Synthetic underlayment has become the go-to choice for many roofing pros—including us—because it offers:

• Higher tear resistance than old-fashioned felt

• Lighter weight, which means easier and safer installation

• Water resistance without wrinkling or puckering

• Better walkability for installers, even in wet conditions

• UV resistance that allows it to stay exposed longer if the weather turns during a project

In North Georgia’s humid, storm-prone climate, that kind of performance matters.

How We Install Synthetic Underlayment

Installing underlayment the right way protects your roof for decades. Here’s how we do it at L&L:

1. Prep the Deck

• We inspect for and replace any damaged decking.

• We ensure the surface is clean, dry, and smooth before starting.

2. Apply Ice & Water Shield (When Needed)

In areas prone to ice damming—typically where January temperatures drop below 30°F—we install a self-adhering ice barrier at the eaves and valleys.

3. Lay Synthetic Underlayment

• We roll it out horizontally, perpendicular to the slope.

• Each course overlaps the last by at least 2 inches on the sides and 4 inches on the ends.

• We secure it with cap nails or plastic cap fasteners no more than 36 inches apart to prevent wind blow-off.

• All seams and fasteners are placed with water-shedding in mind.

For extra protection or steeper slopes, we may use a double-layer installation, starting with a 19" starter course at the eaves, then overlapping each subsequent sheet by 19" to leave a 17" exposed area.

4. Flashing & Edges

• We always install drip edge flashing at the eaves under the underlayment, and at the rakes over it.

• This prevents water from creeping behind the trim and into the sheathing.

Homeowner Tip: Don’t Settle for the Cheapest Option

Not all underlayment is created equal. Some synthetic products are low quality and don’t breathe properly, trapping moisture underneath. That’s why we only use reinforced, code-compliant materials from trusted manufacturers.

Common Questions About Synthetic Underlayment

How long can synthetic underlayment be left exposed?

Most products we use can safely remain exposed for 90–180 days—handy during rainy seasons or larger projects.

Is synthetic better than felt underlayment?

Yes—for most homes in Gainesville, synthetic performs better in strength, weather resistance, and longevity.

Can you use synthetic underlayment under metal or shingle roofs?

Absolutely. It works great under asphalt shingles, metal panels, and even tile—as long as it meets manufacturer and code requirements.

Our Promise

Whether your roof is getting a full replacement or storm damage repair, we install underlayment with the same attention to detail as we do the visible roofing materials. Because when it comes to protecting your home, we don’t cut corners—ever.

Need help with your roof in Gainesville or the surrounding area? Call us at (770) 874-0372 to schedule a free consultation.