What Is a Roof Made Of? (Complete Breakdown of Layers + Materials)

Your roof isn’t just “shingles.” A properly built roof is a system of layers that work together to shed water, handle wind, resist heat, and protect the structure of your home.

If you’re a homeowner in the Denver Metro area, understanding what your roof is made of matters even more—sun exposure, hail season, and temperature swings all put extra stress on roofing materials.

The main layers a roof is made of

Most modern residential roofs (especially asphalt shingle roofs) are built from the top down like this:

1) Roof covering (the visible outer layer)

This is what you see from the street. Common roof coverings include:

• Asphalt shingles (most common in Colorado)

• Concrete or clay tile

• Metal roofing (standing seam or exposed fastener)

• Wood shake (less common today, often due to fire considerations)

• Synthetic options (composites designed to mimic slate/shake)

Job: The roof covering is the first line of defense against sun, rain, and hail.

2) Underlayment (the water-shedding backup layer)

Underlayment is a protective sheet installed over the decking and beneath the roof covering. It can be:

• Synthetic underlayment

• Felt (asphalt-saturated paper) (older standard)

• Ice & water shield (self-adhered membrane used in vulnerable areas)

Job: If wind-driven rain or ice pushes water past the shingles, underlayment helps keep it from reaching the wood deck.

3) Flashing (the leak-prevention “metalwork”)

Flashing is typically metal installed where roofs meet walls or where something penetrates the roof (like a pipe or chimney). You’ll see it at:

• Chimneys

• Skylights

• Roof-to-wall transitions

• Valleys

• Plumbing vents

Job: Flashing directs water away from joints and penetrations—the most common leak points on a roof.

4) Roof decking (the structural wood layer)

Decking (also called sheathing) is usually OSB or plywood nailed to rafters or trusses.

Job: It provides a solid base for everything above it. If the decking is soft, rotted, or poorly installed, shingles and nails can fail prematurely.

5) Ventilation components (intake + exhaust)

Ventilation is part of the roof system even though you don’t always “see” it. Common components:

• Soffit vents (intake)

• Ridge vents or roof vents (exhaust)

Job: Moves hot, moist air out of the attic. Good ventilation helps prevent:

• Ice dam risk

• Premature shingle aging

• Mold/moisture issues in the attic

6) Drip edge and edge protection

Drip edge is metal installed at roof edges (eaves and rakes).

Job: Helps water drip into gutters instead of wicking back into fascia or decking—especially important during snow melt.

7) Fasteners and sealants (the hidden work)

Nails, cap nails, specialty fasteners, and sealants are easy to overlook, but they matter.
Job: Correct fastening patterns improve wind resistance; proper sealing helps prevent leaks at penetrations.

What material is “most roofs” made of in Denver Metro?

Most homes have asphalt shingles over synthetic underlayment and OSB decking, with metal flashing at all critical transition points. That’s the standard system we inspect most often.

Signs one of your roof layers may be failing

You don’t have to climb up there—watch for:

• Water staining on ceilings/walls

• Shingle granules collecting in gutters

• Missing/creased shingles after wind

• Rusted or lifted flashing around chimneys/sidewalls

• Soft spots (a roofing pro can detect this safely)

• Ice buildup at eaves in winter (possible ventilation/insulation issue)

When to call a roofer (and what to ask)

If you suspect a leak, storm damage, or shingle loss, an inspection should include:

• Photos of decking condition (where visible)

• Flashing evaluation (chimneys, walls, valleys)

• Underlayment exposure checks (if shingles lifted/missing)

• Ventilation overview

FAQ

What’s the most important part of a roof?
It’s the system. Shingles alone won’t prevent leaks if flashing or underlayment fails.

Is underlayment required?
Yes—underlayment is a standard part of modern roofing and is often required by code/manufacturer specs.

Can my roof leak even if shingles look fine?
Yes. Flashing, pipe boots, valleys, or hidden underlayment issues can leak before shingles look “bad.”

Does hail damage affect only shingles?
Not always. Severe hail can damage vents, flashing edges, soft metals, and even exposed components.

If you’re in the Denver Metro area and you’d like a clear, photo-documented assessment of your roof system, we can help. We’ll walk you through what we find and what it means—no pressure.
Schedule your roof online inspection today.