More than the shingles you see

What goes under a GAF shingle roof.

The shingles are only the top layer. See the wood underneath, the layers that help keep water out, and the vents along the roof peak. Rotate this GAF shingle roof, pull the layers apart, and select a part to find out what it does.

Roof system explorerLayer diagram

The lightweight layer diagram is ready. Interactive 3D loads as this section enters view.

Eight parts. One roof.

Select a component

The surface you see every day

GAF Timberline HDZ

Sheds rain and gives your roof its finished appearance.

These overlapping shingles are the part you see from the street. Your estimate names the shingle product and color, and your warranty documents explain the material coverage.

The layer guide above is available without JavaScript. Enable JavaScript to rotate and separate the roof.

Roof decking: Wood beneath the roofing

Gives the roofing a solid surface to fasten to.

We check the exposed wood after removing the old roofing. Your estimate identifies any allowance for replacing damaged sheets before the new layers go on.

Metal drip edge: Metal flashing at the roof edge

Directs water away from the deck edge and toward the gutters.

This metal trim covers the roof edges. It helps carry runoff away from the exposed wood and works with the underlayment and the first rows of shingles.

Leak barrier: GAF WeatherWatch

Adds a water-resistant layer where leaks are more likely.

This membrane sticks to the deck beneath the roofing. It adds protection in the areas listed in your proposal, such as valleys where two roof slopes meet. Here, the roof edge is opened up to show the layer.

Synthetic underlayment: GAF FeltBuster

Adds another protective layer below the shingles.

This sheet covers the wood beneath the shingles as a second layer of protection. How it overlaps and joins the flashing matters, so installation follows the manufacturer’s requirements.

Starter strip: GAF Pro-Start

Supports the first row of shingles at the roof edge.

Starter strips sit beneath the first row of shingles along the roof edges. Their adhesive helps those edge shingles seal when installed as directed.

Architectural shingles: GAF Timberline HDZ

Sheds rain and gives your roof its finished appearance.

These overlapping shingles are the part you see from the street. Your estimate names the shingle product and color, and your warranty documents explain the material coverage.

Ridge ventilation: An air outlet along the roof peak

Lets warm, moist attic air exit through the ridge.

Warm attic air can leave through this vent at the peak. It needs suitable intake vents lower down so air can move through the attic. Your roof and attic determine the layout; more vents are not always better.

Ridge cap shingles: GAF Seal-A-Ridge

Finishes and protects the hips and roof peak.

These shaped shingles cover the roof peak and the raised lines where sloping sides meet. Over a ridge vent, they finish the top while leaving the vent’s airflow path open.

This model explains a GAF shingle roof. Your written estimate names the products and installation details for your home; the exact roof build and warranty terms can differ.

Always-visible layer guide

Eight parts shown in the roof model.

The interactive view helps you see where each part sits. This complete text guide explains what every layer does without requiring the 3D controls.

Roof decking
Wood beneath the roofing
Gives the roofing a solid surface to fasten to.
We check the exposed wood after removing the old roofing. Your estimate identifies any allowance for replacing damaged sheets before the new layers go on.
Metal drip edge
Metal flashing at the roof edge
Directs water away from the deck edge and toward the gutters.
This metal trim covers the roof edges. It helps carry runoff away from the exposed wood and works with the underlayment and the first rows of shingles.
Leak barrier
GAF WeatherWatch
Adds a water-resistant layer where leaks are more likely.
This membrane sticks to the deck beneath the roofing. It adds protection in the areas listed in your proposal, such as valleys where two roof slopes meet. Here, the roof edge is opened up to show the layer.
Synthetic underlayment
GAF FeltBuster
Adds another protective layer below the shingles.
This sheet covers the wood beneath the shingles as a second layer of protection. How it overlaps and joins the flashing matters, so installation follows the manufacturer’s requirements.
Starter strip
GAF Pro-Start
Supports the first row of shingles at the roof edge.
Starter strips sit beneath the first row of shingles along the roof edges. Their adhesive helps those edge shingles seal when installed as directed.
Architectural shingles
GAF Timberline HDZ
Sheds rain and gives your roof its finished appearance.
These overlapping shingles are the part you see from the street. Your estimate names the shingle product and color, and your warranty documents explain the material coverage.
Ridge ventilation
An air outlet along the roof peak
Lets warm, moist attic air exit through the ridge.
Warm attic air can leave through this vent at the peak. It needs suitable intake vents lower down so air can move through the attic. Your roof and attic determine the layout; more vents are not always better.
Ridge cap shingles
GAF Seal-A-Ridge
Finishes and protects the hips and roof peak.
These shaped shingles cover the roof peak and the raised lines where sloping sides meet. Over a ridge vent, they finish the top while leaving the vent’s airflow path open.

What about your roof?

See what your roof needs.

We inspect your roof for free, show you the photos, and explain the recommended materials and price in a written estimate.

Read the Houston roof estimate guide or learn about TexaShield roof replacement.

Request a free roof inspection Call 713.818.7086