Low Pitch Roofing Underlayment For Shingles

The acceptable underlayment installation options for low slopes are described in the canadian standards association asphalt shingle application standard csa a123 51 as follows.

Low pitch roofing underlayment for shingles.

For starters the textured underlayment isn t just weatherproof. Most manufacturer and industry recommendations require or at the very least recommend special underlayment or other considerations on roofs between 2 12 and 4 12. Start with a 19 inch strip of 15 lb. Despite its wide range of compatibility it still does offer a bit more whenever you re dealing with asphalt shingles.

Cover the entire low sloped roof area with a self adhered modified bituminous membrane that will act as an ice and water. Asphalt saturated felt along the eaves and lap succeeding courses by 19 inches as shown in figure 2 3. For a low slope residential roof there are two main options. Asphalt shingles can be used on roofs with a slope of 2 12 to 4 12 if double coverage underlayment is used.

Product overview if you re looking for the best roof underlayment for asphalt shingles then the tyvek protec 120 should be on your wishlist. When combined with the proper underlayment materials and application they are an excellent solution for a low slope roof with a pitch between 2 12 to 4 12. Because of the non absorbent nature of asphalt the shingles themselves provide an element of waterproofing which is why they work well for low slopes. As well a slope of 4 12 is most commonly considered the lowest slope for standard shingle installations.

1 cover the entire surface with a self adhesive flashing membrane such as grace ice water shield there are many equivalent products.