Every homeowner understands how vital a roof is to their home’s structural integrity and beauty. In addition, a roof allows for adequate ventilation and insulation from the heat and cold of the summer.

Strong roofs go beyond shingles. Learn more about roofing underlayment. This vital layer protects your roof from the elements and keeps it dry.

What is Roofing Underlayment?

Roof underlayment is a barrier material that is usually installed directly on your roof deck. The skeleton of your roof depends on the construction of your home. It may consist of rafters, trusses, or both.

Roof deck, sometimes referred to as roof sheathing or roof deck, could be:

• Plywood
• OSB, or
• Step sheathing

These boards are attached to the roof rafters and trusses to stabilize them or give structure to the whole roof.

This roofing underlayment covers the sheathing material. This provides a second layer of protection against moisture intrusion if water gets under your shingles.

Types of roofing underlayment

There are three types of roofing underlayment available: synthetic, self-adhered and felt. Each type has its advantages and disadvantages. The roofing underlayment you choose will depend on the experience and requirements of your contractor and local building codes.

Felt Underlayment

Felt is the oldest type of roofing underlayment. This is also known as tarpaper and felt paper. It is made from an organic mat or paper, which has been saturated with asphalt for water resistance.

Felt underlayment comes in two weights.

• 15 Pounds per 100 square feet, or No. 15 felt
• 30 Pounds per 100 square feet, or No. 30 felt

For lightweight projects, No. No. 15 felt is acceptable for light tasks. It can tear easily and, if left out in the elements, can absorb water and wrinkle.

Contractors may recommend No. 30 felt underlayment for homeowners who choose felt. No. 30 felt is more robust than No. 15 felt. You can use it in multiple layers to provide additional protection, as with all underlayment products.

Some roofing contractors use felt underlayment when working with slate or tile roof shingles. Others prefer self-adhered. It all depends on where you live.

Self-Adhered Coverage

This type of underlayment is made up of high amounts of asphalt and rubber polymers. It’s water-resistant, which makes it an ideal solution for roofing underlayment.

The sticky backing on self-adhered roof deck underlays allows them to stick to the roof deck. In addition, the sticky support creates a waterproof seal between your roof deck and the underlayment. 

This underlayment protects the roof from water damage and penetration into the roof deck.

These areas are susceptible to leakage such as:

• Eaves
• Valleys
• Vents
• Chimneys and
• Skylights

In areas that experience severe winter weather, self-adhered blankets are handy.

This roofing underlayment can have granulated, polyester, or polyethylene materials on the upper surface. These materials provide weather-resistant benefits. In addition, this non-skid surface is intended to make roofing easier and safer by making it easier to install.

Synthetic Underlayment

In the past decade, synthetic roofing underlayment has become a trendy choice for homeowners. Although materials can vary from manufacturer to manufacturer, synthetic roofing underlayment comprises layers of different polymers woven together.

Synthetic underlays often have many advantages.

• Durable, rugged and tear-resistant
• You will be able to reduce ladder trips by being lighter and having more coverage per roll (in contrast to other types of underlayment).
• Walking safe surface
• Clear, well-delineated lines with overlap guides are essential for a better installation
• Repels water and is inert toward mold

Why is Roofing Underlayment necessary?

Your shingles are your first line of defense in the ever-changing battle against the elements homeowners and contractors wage. Shingles can reflect the sun’s rays and resist high winds.

Roof underlayment provides an additional layer of protection.

• Protect your roof from high winds and shingles falling off
• Protect your roof deck against damage from ice dams during cold snaps
• Protect your roof from the elements during installation before attaching shingles.

Your home’s roof system must meet all local building codes. It should include a roofing product and roof covering. A shingle manufacturer will require to have an underlayment in their warranty.

Locate a Roofing Contractor near You

A roofing contractor such as Framingham Roofing MA can answer questions about sheathing, underlayment, and other materials that protect your home from the elements.