By Custom Home Renovations | Serving Annapolis, Severna Park, Millersville, Kent Island & Anne Arundel County, MD
Most homeowners know what shingles are. They’re the visible surface of the roof — the part you can see from the street and the part that takes the most obvious abuse during a storm. But far fewer homeowners know about what lives underneath the shingles, and what happens when that hidden layer is compromised.
We’re talking about the roof underlayment — and in Maryland’s climate, where summer storms can bring sudden heavy rain, high winds, and hail, understanding this component can mean the difference between a minor repair and a major interior water damage event.
What Is Roof Underlayment?
Roof underlayment is a water-resistant or waterproof barrier that sits between the roof decking and the shingles. It serves as a critical secondary line of defense: if shingles are lifted, torn away, or cracked during a storm, the underlayment is what prevents water from immediately reaching the roof deck. There are three main types used in residential roofing throughout Anne Arundel County:
Felt underlayment (tar paper) — the traditional option, still widely used and effective when properly installed
Synthetic underlayment — a newer, lighter, and more durable option that resists tearing
Self-adhering ice and water shield — a peel-and-stick membrane used in the most vulnerable areas: eaves, valleys, around chimneys and skylights, and anywhere ice dams are likely to form
For homes in Annapolis and coastal Anne Arundel County, ice and water shield is especially important given the ice dam risk during Maryland winters and the wind-driven rain risk during summer storm season.
Why Underlayment Matters During a Storm
Here’s the scenario that plays out more often than most homeowners realize: a severe thunderstorm rolls through Severna Park or Arnold in July. Wind gusts hit 60+ mph and lift several shingles. If the underlayment is intact and in good condition, you likely have time to get a contractor on the roof before water infiltrates the decking. If the underlayment is old, brittle, or torn, water reaches the roof deck immediately. This is why we always assess underlayment condition during our storm damage inspections throughout Anne Arundel County.
Signs Your Underlayment May Be Compromised
Water stains on interior ceilings or in attic spaces, even when shingles appear intact from the ground
- Visible daylight in the attic — a sign of gaps that extend through multiple layers
- A roof that is more than 15-20 years old with aging underlayment to match
- Previous storm events where shingle damage was repaired without inspecting the underlayment beneath
- Moss or algae growth indicating persistent moisture
How Underlayment Factors Into Insurance Claims
When we file storm damage insurance claims for homeowners throughout Annapolis and Anne Arundel County, underlayment condition is part of our documentation. A damaged or deteriorated underlayment caused by a storm event strengthens the case for a full roof replacement rather than a surface-level shingle repair.
If your home has been through a significant storm, don’t rely on a ground-level visual check. Call Custom Home Renovations at 443-333-1589 or schedule your free inspection online at chrhomesmd.com.
Custom Home Renovations proudly serves Annapolis, Severna Park, Arnold, Millersville, Pasadena, Edgewater, Kent Island, and surrounding communities throughout Anne Arundel County, PG County, and Howard County, Maryland. MHIC: 130731.
