If you need a new roof, then you may be most concerned about the shingles that make up the physical roof. However, there are several parts to a roof that includes the deck and the underlayment. While the deck rarely needs to be replaced, the underlayment does often need replacing. You may be wondering what the underlayment is and why it is important. Keep reading to learn to learn what the underlayment does for your roof.
It Keeps Water Away
The Most important function of the underlayment is to keep water away from the roof deck. In other words, it helps to prevent leaks in the actual roof deck. The underlayment may be made out of several different types of materials to keep leaks at bay. Felt saturated with asphalt, rubberized asphalt, and synthetic underlayment are the three main types. While rubberized and synthetic materials are appropriate in some situations, these materials are most often used as a base for flat roofs.
Felt asphalt materials are the most common and are usually called felt or tar paper. The material is exactly what it sounds like. It is a cellulose, polyester, or other material that is covered with a layer of asphalt. The asphalt is a water resistant petroleum based fluid that forces water to bead off the surface if water comes into contact with it.
Most of the water that comes into contact with tar paper will form condensation, and the water will evaporate. Large amounts of water can collect on the tar paper and be chanelled down the roof to the eave. However, this sort of leak will penetrate the tar paper eventually and will soak through the deck.
It Can Prevent Fires
The roof underlayment directly covers the roof deck and this helps to protect it from more than just water. The felt material also keeps smoke and fire damage at bay. Specifically, different types of underlayment are rated for fire protection. Residential homes may not require the protection, but it is wise.
The fire ratings are named A, B, and C. Almost all underlayments are resistant to smoke, but B and C materials do not prevent fires as well as class A materials. Class A underlayments are often thicker than other options. Keep this in mind, because this can increase your overall roofing cost.
If you want to know more about underlayment materials and which one is best for your home, make sure to speak with your roof installation professional.