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Is Roofing Felt Waterproof?

Roofing felt, a typical building material, protects structures from moisture. However, the question remains: Is roofing felt waterproof?

Roofing felt, tar paper, or underlayment is composed mostly of cellulose, fiberglass, or polyester impregnated with bitumen – a hydrocarbon-based substance. Its major role is to provide additional protection from weather factors by acting as a barrier between the roof deck and the roofing material, such as shingles or metal.

Our highly professional and competent workforce of Only Roofing Contractors Spring TX recommends the installation of roofing underlayment as an additional protection shield to keep the moisture-related home damage at bay.

Water-Resistance vs. Waterproof

Before finding out ‘Is roofing felt waterproof?’, you must understand the difference between water resistance and waterproofing ability.

While roofing felt is water-resistant, stating that it is completely waterproof is a stretch. It may resist water to a certain amount, preventing it from penetrating the underlying structure. However, in harsh weather circumstances or when exposed to moisture for an extended time, roofing felt may eventually enable water penetration due to poor installation and the complete absence of regular care.

Waterproofing Influencing Factors

Several elements determine the waterproofing capability of roofing felt. The thickness, quality, installation technique, exposure to UV radiation, and temperature variations all play important roles in the material’s performance. Thicker felt with higher grade bitumen is more water resistant.

Roofing felt minimizes the danger of water intrusion into the roof structure greatly. It offers a protective barrier, insulating the roof deck from water damage, which can cause structural degradation, mold, and rot when properly installed with other roofing materials.

Considerations for Maximum Security

Additional efforts can be made to improve waterproofing. Regular maintenance, ensuring appropriate overlap during installation, and quickly fixing any splits or punctures all help extend the roofing felt life.


In principle, knowing ‘Is roofing felt waterproof?’ is essential to protect your living place against moisture. However, characterizing the material as completely waterproof may be exaggerating its capabilities. When paired with roof replacement Woodlands services and regular care, its position as a water-resistant layer contributes greatly to protecting structures from the destructive effects of water penetration.