Did you know roofing felt has protected homes for over a century? This vital layer sits between your roof deck and shingles to keep your home dry and secure. The National Roofing Contractors Association (NRCA) has included roofing felt in its roofing and waterproofing recommendations for more than 25 years.
Roofing felt works as a protective underlayment that blocks excess moisture from entering your home. Manufacturers create it from natural materials like wood cellulose soaked in a protective asphalt layer (bitumen) that gives it water-shedding properties. Some versions use recycled paper products with asphalt. The material resists water but isn’t completely waterproof. Your home stays protected during extreme storms, heavy rains, and snow. This “black paper for roofing” does more than just keep moisture out – it helps your roof meet Class A fire ratings.
What is roofing felt, and what is it made of?
Roofing felt serves as a protective layer between your roof deck and exterior materials like shingles. Water-resistant substances coat this underlayment’s base material. Your roofing system can use several distinct options because the base material differs among products.
Wood cellulose and recycled paper products were the traditional materials used in roofing felt paper. Manufacturers have now created more durable options. Fiberglass has become the top choice and makes up 75% of all shingles in North America. This transformation happened because fiberglass performs better than traditional materials with its dimensional stability and natural flame resistance.
Polyester proves to be another effective base material. Products made with fiberglass reinforcement can withstand winds up to 150 miles per hour. Both materials excel at resisting tears.
The felt’s water-shedding abilities come from waterproofing substances, mainly bitumen (asphalt), that coat these products while letting them breathe. A properly installed roofing felt creates a highly water-resistant barrier, though not completely waterproof.
State-of-the-art products include thermoplastic polyolefin membrane (TPO) underlayments with better puncture resistance and slip-resistant coatings that make installation safer on steep roofs. Modern products feature enhanced nail-sealing properties and come in sheets wider than traditional 36-inch rolls.
What is the purpose of roofing felt?
Roofing felt plays several key roles in your home’s roofing system. It works as a secondary water barrier that kicks in when your main roofing material fails. Your shingles might get damaged or come loose in bad weather, but this underlayment keeps water from getting into your house’s structure.
The felt creates a flat, smooth surface to install shingles. This prevents what contractors call the “picture framing” effect – you don’t want your wood decking patterns showing through your shingles as time passes.
The felt also protects your roof deck from moisture that could rot the wood and damage the structure. This protection helps your roof last longer. Your roof’s fire rating can improve, too – your shingles might not meet Class A fire standards without proper underlayment.
Resin stains don’t stand a chance with roofing felt. Wood roof decks naturally release resins that could stain your roofing material, but the felt stops this from happening[101].
The felt layer shields your roof from rain, snow, and wind during installation. People living in cold regions get extra protection against ice dams that form when their home’s heat melts the roof snow.
Types of roofing felt and how to choose
Your choice of roofing felt should match your climate, roof pitch, and budget. You can find traditional roofing felt in two standard weights: 15-pound and 30-pound. The 30-pound felt provides better protection for steep roofs and won’t tear as easily.
SBS-modified felt works best in cold climates because it stays flexible even when temperatures drop below freezing. Breathable membranes are the perfect choice for damp regions. They let moisture vapor escape while keeping the rain out.
The market now offers several modern alternatives to traditional felt:
- Torch-on felt: Heated during installation, designed to withstand heavy loads and extreme weather
- Self-adhesive felt: Easier to install with decent moisture protection
- Synthetic underlayment: Four times lighter than traditional felt, tears less easily, and offers superior water repellency
Here’s how different felts perform in various climates:
| Felt Type | Cold Climate | Damp Climate | Cost |
| Standard | Poor-Moderate | Poor-Moderate | Low |
| Torch-On | Excellent | Good | High |
| SBS Modified | Excellent | Excellent | High |
Building codes require double layers of underlayment for low-slope roofs (2:12 to 4:12). This requirement exists because these roofs face a higher risk of water infiltration.
Conclusion
Roofing felt does much more than just add another layer to your roofing system. This simple material provides significant protection against water damage. It shields your roof from the weather during installation and helps it last longer. It also creates a smooth surface for shingles and might boost your roof’s fire rating.
Your climate conditions, roof pitch, and budget should guide your choice of roofing felt. The traditional 15-pound and 30-pound felts have kept homes safe for decades. Modern options like synthetic underlayments and SBS-modified felts now offer improved protection with added benefits.
Quality underlayment affects your roof’s ability to handle extreme weather. A small investment in better roofing felt can prevent water damage and structural problems later. Talking to qualified roofing professionals about the best underlayment for your needs could save you money and reduce stress over time.
Learning about roofing felt helps you make smart choices about this vital part of your home’s protection system. You might not see it, but this layer quietly keeps your home dry, secure, and strong through the years.
FAQs
Q1. Is roofing felt completely waterproof?
Roofing felt is not completely waterproof, but it is highly water-resistant. It acts as a secondary water barrier, protecting your home from moisture infiltration if the primary roofing material fails. While it can effectively shed water, it’s designed to allow some breathability.
Q2. What are the main purposes of roofing felt?
Roofing felt serves multiple purposes: it provides a secondary water barrier, creates a smooth surface for shingle installation, protects the roof deck from moisture damage, improves fire ratings, prevents wood resin stains, and offers temporary protection during roof installation.
Q3. How do I choose the right type of roofing felt?
Choosing the right roofing felt depends on factors like your climate, roof pitch, and budget. Consider options such as traditional 15-pound or 30-pound felt, synthetic underlayments, or specialized products like SBS-modified felt for cold climates. For low-slope roofs, double layers may be required.
Q4. What are the advantages of synthetic roofing felt over traditional felt?
Synthetic roofing felt is typically four times lighter than traditional felt, more tear-resistant, and offers superior water repellency. It’s often easier to install and can provide better protection in extreme weather conditions. However, it may be more expensive than traditional options.