Using the chalkline as a guide, roll out about 12 feet of WSU smooth and free of creases and bubbles. Often you can reroll it, then unroll it while peeling off the paper backing. On a steep roof, you can adhere the bottom half first, then pull off the backing from above. Avoid creases and stay aligned with the chalkline. Press down to tightly seal the WSU.
When the weather promises to stay dry, many roofers prefer to install underlayment as they go. Apply one or two courses of WSU or felt, install the shingles, then apply more felt when you come within 6 inches of the top edge. No matter which valley method you use, for extra protection apply WSU at a valley.
Snap chalklines on both sides for guides. Roll out and smooth the WSU and drive a few nails on one side to hold it temporarily. Fold over the other side and peel off the paper backing.
Press into place, remove the nails, and peel off the paper on the other side. Overlap felt courses at least 4 inches. Snap a chalkline 32 inches above the top edge of the WSU or use the lines on the felt as guides.
If you use the lines as guides for installing shingles, measure up from the drip edge to confirm that you stay parallel. Roll out the felt, eliminating creases or bubbles, and drive at least three staples every foot. Apply felt right up to the ridge or to no more than 4 inches below it. Rather than cutting the felt horizontally to fit, overlap it by more than 4 inches.
Apply felt on the ridge so it overlaps at least 8 inches on each side. Eliminate creases and bubbles. Where the roof meets a wall, lap the felt up 4 inches if possible. The majority of roofing manufacturers advise that you use four nails for each shingle for the roofing main area and use five nails for each roofing underlayment square. For you who live in windy areas, you may want to use nails per square.
The most commonly used nail type is the 1. This type of nail weighs 1 lbs for nails. Synthetic underlayment has existed since the early s with various types available.
You can find spun or woven synthetics that are created from polypropylene or polyethylene. Each type has different characteristics, such as thickness, manufacturing procedure, walkability, and exposure time, but generally, the ingredients are quite similar. Synthetic underlayment is usually differentiated to their weight and their feeling. The unit used to estimate the synthetics are grams-per-square-meter GSM.
How many roofing nails per square of synthetic underlayment required is the same as the common underlayment calculation above. Should underlayment be screwed to joists? The underlayment is the middle layer of the floor. This layer is installed directly on top of the sub floor.
The underlayment is usually stapled to the sub floor with a pneumatic stapler, but can be fastened through the subfloor into the joists with nails or screws instead. Does subfloor need to be glued? Although using a subfloor adhesive is not required by code, it is a standard practice that can help prevent floor squeaks by reducing the chance for movement at the panel-to-joist connection.
A quality subfloor adhesive will also increase the overall stiffness of the floor. How thick should Plywood be for flooring? The thickness of your plywood subfloor depends on the joist spans. Do I need to glue plywood to subfloor? Use subfloor adhesive, and screw 8" at edges, 12" in field.
Adhesive will help you here, as the subfloor plywood will have voids in spots that will not hold a fastener. Can I use drywall screws for subfloor?
Drywall screws should only be used for drywall, and a temporary coat hanger. You want more strength and need less space for the threads to secure the subfloor. The drywall screws have a lot of thread to hold the drywall itself, but have very little shear strength. In the field between the joists, they are fine.
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