What is underlayment and why is it installed?

What is underlayment and why is it installed?

• A. A secondary waterproof layer beneath the roof covering to protect the deck
• B. A primary insulation layer
• C. A decorative coating
• D. A protective finish for gutters

Answer: (A)

Underlayment is the layer installed between the roof deck and the final roof covering. Its job is to provide a second, waterproof barrier that protects the deck from any moisture that gets through or around the outer roofing material, such as wind-driven rain or leaks at seams and fasteners. It also gives a weatherproof surface during installation and protects the deck while the roof is being completed. It isn’t the main insulation of the building, it isn’t decorative, and it isn’t a protective finish for gutters. Different types exist, like asphalt-saturated felt or synthetic underlayments, but the core idea is a secondary waterproof layer beneath the roof covering to shield the deck.

Underlayment is the layer installed between the roof deck and the final roof covering. Its job is to provide a second, waterproof barrier that protects the deck from any moisture that gets through or around the outer roofing material, such as wind-driven rain or leaks at seams and fasteners. It also gives a weatherproof surface during installation and protects the deck while the roof is being completed. It isn’t the main insulation of the building, it isn’t decorative, and it isn’t a protective finish for gutters. Different types exist, like asphalt-saturated felt or synthetic underlayments, but the core idea is a secondary waterproof layer beneath the roof covering to shield the deck.