Roofing felt is waterproof, but only to a point. It stops some water, but it is not fully waterproof like modern roofing materials. Roofing felt acts as a barrier under your shingles. It slows down water that leaks past the shingles. Over time, felt can dry out and crack. This lets water seep through and damage your roof. Understanding what felt does helps you protect your home better.
What Is Roofing Felt Made from?
Roofing felt is a layer of material placed under shingles. It is made from plant fibers mixed with tar or asphalt. The tar makes it water resistant, not waterproof. Felt comes in rolls and is stapled to the roof deck before shingles go on.
Most felt is 15 pounds or 30 pounds thick. Thicker felt lasts longer and stops more water. But all felt will break down over time.
Related articles:
- What Side of Roofing Felt Goes Down
- What Is Felt in Roofing
- How Much Is Roofing Felt
- How to Install Roofing Felt
- How to Apply Roofing Felt
- How Do You Lay Roofing Felt
- What Is Felt Roofing
- Is Roofing Tar Paper Waterproof
How Long Does Roofing Felt Last?
Roofing felt does not last as long as shingles. According to RubyHome (2025), asphalt shingles last 20 to 30 years. But felt breaks down much faster. Most felt lasts only 12 to 15 years before it cracks and fails.
Hot sun dries out felt. Rain and wind damage it. Poor attic ventilation speeds up this breakdown. According to industry data, ventilation is a key factor that affects roof lifespan. When attic airflow is bad, felt rots faster and lets water in.
Felt Vs. Modern Waterproof Barriers
Today, many roofers use synthetic underlayment instead of felt. These new materials are much more waterproof. They do not dry out like felt. They last 25 to 50 years or more. Synthetic barriers are stronger, lighter, and better at stopping water.
Here is how they compare:
| Material | Waterproof Rating | Lifespan |
|---|---|---|
| Asphalt Felt | Partial | 12-15 years |
| Synthetic Underlayment | Highly Waterproof | 25-50 years |
Why You Should Replace Felt Early
If your roof is over 20 years old, the felt underneath is likely failing. According to RubyHome (2025), the average age of roofs being replaced is just over 19 years. This is because both shingles and felt wear out around the same time.
Water leaks cause 33 percent of roof replacement needs, according to industry data. If felt cracks, water sneaks through. It sits in your attic and causes rot, mold, and structural damage. These repairs cost thousands of dollars. Replacing felt early stops this damage.
When you get a new roof, choose synthetic underlayment instead of felt. It costs a bit more but lasts much longer. According to RubyHome (2025), roof replacement costs range from $5,868 to $13,217 on average. Adding better underlayment adds only a small amount to this cost. It protects your home for decades.
Related articles:
- Can Roofing Felt Get Wet
- How Long Can Roofing Felt Stay Exposed
- What Is Roofing Felt
- Is Roofing Paper Waterproof
- How to Lay Roofing Felt
- Can I Use Roofing Felt Under Vinyl Plank Flooring
- How to Attach Roofing Felt
- How Long Does Roofing Felt Last Under Tiles
Work with a professional roofing services to protect your property with quality roofing solutions.