Underlayments require a continuous substrate to support the underlayment material. Different building codes recommend using underlayments with any asphalt shingle roof systems. An underlayment is applied over an entire roof deck before applying asphalt shingles.
An underlayment performs several functions and provides:
- Weather protection for a limited time
- A secondary water barrier (SWB)
- The separation between a roof covering and the substrate
Why are underlayments required:
- To comply with the applicable building code
- To comply with a Class A fire rating for a roof assembly
- To meet the manufacturer’s requirements
Underlayment should be used carefully. This is because, in different climates, air leakage can create condensation problems.
What underlayment styles are available? Underlayment Requirements for Shingle Roofs
- Single or double layer of mechanically attached underlayment
- Self-adhering underlayment
What are different underlayments used in south Florida under new FBC 2023 8th edition?
Underlayment for asphalt shingles, metal roof panels or shingles, mineral surfaced roll roofing, slate and slate-type shingles shall comply with one of the following methods:
- Self-Adhered Direct to Deck
- Taped joints or sealed joints system
- Two Layers of Nailable Underlayment
In South Florida, For single-layer applications, the underlayment should be applied horizontally in a shingle fashion and lapped as recommended by the manufacturer.
Typically, side laps of a minimum of 6 inches and end laps of 4 inches are required.
Single-layer of Self-adhering Underlayment consists of the layer of self-adhering polymer-modified bitumen sheet applied over an entire roof deck.
Miami Dade County Building has developed strict recommendations and procedures for underlayments installations in high-Velocity areas or Hurricane zones as we know them.
You must hire roofing professionals to receive quotes, inspections, or any consultation regarding the use of underlayment for your home roof.
Now that you are familiar with the above section’s construction and installation details don’t hesitate to contact us to schedule a free roof inspection/quote.
