If you don’t work in the roofing industry, your knowledge of roofing materials may be limited to shingles, and well . . . shingles. You may be aware that there are other types of roofs – especially for commercial buildings or those with metal roofing.
However, another layer plays a critical role in safeguarding your home from moisture damage – roofing underlayment.
What Is Roofing Underlayment?
Roofing underlayment is an essential part of your roofing system. It lies between the shingles and the roof deck and provides a secondary layer of protection from the elements. There are two types of roofing underlayment: felt and synthetic.
Today we would like to discuss the pros and cons of each type of roofing underlayment system.
Felt Roofing Underlayment
Felt roofing underlayment is a tried and tested material created by saturating paper or fiberglass mat with asphalt. There are two types of felt underlayment. No. 30 felt is typically thicker and is less prone to tearing or ripping off during installation than the other type – No. 15.
Felt underlayment typically costs less compared to synthetic underlayment. However, there are several disadvantages of using traditional felt. One disadvantage is that felt underlayment generally can’t be left exposed for more than a few hours as it can absorb water or wrinkle in the heat. (Under layment needs to lay flat underneath the shingles.)
Felt underlayment is also prone to tearing during installation. Additionally, it weighs more than the synthetic underlayment rolls, which makes it harder for roofing contractors to carry it on top of your roof. Finally, because the rolls are so heavy, there is typically less material per roll, so there will be more seams beneath your shingles.
(It’s also worth noting that using felt underlayment may prevent you from being protected under the manufacturer’s warranty. Ask your roofing pros if that is the case for your project.)
Synthetic Roofing Underlayment
Synthetic roofing underlayment is a more modern option. These products are usually made from durable polymers, which means they are more moisture-resistant than the felt option.
Besides being better able to repel water, synthetic underlayment is tough material. It has an extremely high tear strength compared to felt and stands up to foot traffic.
Synthetic roof underlayment is highly durable. It typically doesn’t tear and can handle a bit of moisture exposure, which is especially helpful if there’s a bit of wait time before shingles can be installed.
Even though it is stronger, the rolls of synthetic roofing underlayment are lighter. This means that there’s more material per roll compared to felt, which results in fewer trips up the ladder for your roof contractors and fewer seams on your roof. Generally, it is a safer material, as synthetic roofing underlayment materials are also made with slip-resistant surfaces.
Finally, homeowners concerned about moisture infiltration (and what homeowners aren’t worried about this?) can rest easy knowing that synthetic underlayment blocks water and is typically resistant to mold growth.
However, many synthetics cost more when compared to felt. So while investing in quality roofing materials can benefit you in the future, you may have to pay a higher upfront cost to install synthetic underlayment.