In the construction industry, “felt,” also known as underlayment, refers to a material installed between the roof deck and the final roofing material to provide an additional layer of protection against water infiltration and damage.
Characteristics:
1. Waterproofing: Felt underlayment acts as a waterproof barrier, preventing water from penetrating the roof deck and causing damage to the underlying structure. It serves as a secondary line of defense against leaks, particularly in areas prone to heavy rain or snowfall.
2. Moisture Management: In addition to waterproofing, felt underlayment helps manage moisture within the roof assembly by allowing for the evaporation of trapped moisture and condensation. This helps maintain the integrity of the roofing system and prevents issues such as rot, mold, and mildew.
3. Protection: Felt underlayment provides protection to the roof deck during the roofing installation process, shielding it from damage caused by foot traffic, tools, and other construction activities. It also helps to smooth out any irregularities in the roof deck, creating a flat and uniform surface for the final roofing material.
4. Insulation: While primarily designed for waterproofing and protection, some types of felt underlayment may also provide a degree of thermal insulation, helping to improve the energy efficiency of the building and reduce heating and cooling costs.
Installation and Types:
Felt underlayment is typically installed in overlapping layers, starting from the eaves and working upward toward the ridge of the roof. The seams between adjacent rolls or sheets are sealed using adhesives or fasteners to create a continuous barrier against water infiltration.
There are various types of felt underlayment available, including asphalt-saturated felt, synthetic underlayment, and self-adhering underlayment. Each type offers different advantages in terms of durability, ease of installation, and resistance to UV exposure and weathering.
Maintenance:
Regular inspection and maintenance of felt underlayment are important to ensure its continued effectiveness in protecting the roof structure. This may include checking for tears, punctures, or areas of deterioration, especially after severe weather events, and repairing or replacing damaged sections as needed.
Example Sentence:
Before installing the shingles, the roofing contractor carefully laid down a layer of felt underlayment to provide an additional barrier against water infiltration and protect the roof deck from damage.
