Can you use 2 layers of roofing felt?
I typically install 15-pound felt under standard three-tab asphalt shingles and 30-pound felt under architectural shingles. On low-sloping roofs with a pitch of 3-in-12 or less, I use two layers of felt. … If your roof isn’t leaking, I would not recommend any changes.
How much roofing underlayment do I need?
Underlayment usually comes in rolls of 4 squares each. So, covering 240 squares would require 60 rolls of underlayment. No underlayment is needed if you are applying shingles directly over an existing asphalt roof. Be sure to add 10% to all of your material totals for trim allowance.
Can you put 2 layers of plywood on a roof?
The new plywood will have to be nailed to the rafters or roof trusses. … That increase in weight should not be a problem with the single layer of asphalt shingles you will be installing, because it is normally safe to assume the roof structure is built to support the weight of two layers of asphalt shingle roofing.
What is the minimum underlayment for asphalt shingles?
for asphalt shingles, NRCA recommends a single layer of no. 15 asphalt-saturated underlayment be used with roofs having slopes of 4:12 (18 degrees) or greater. for roof slopes between 3:12 (14 degrees) to 4:12 (18 degrees), NRCA recommends a minimum of two layers of no. 15 underlayment.
How many layers of felt do I need for a shed roof?
Felt layers. 1,2 or 3 layers are usual. Habitable work should use 3 layers, sheds more often use 2, sometimes 1. Underlay and top capsheet layers aren’t identical.
What is the best roofing underlayment?
Synthetic Underlayment
This is currently the most popular choice for roof underlayment, and with good reason. Made with an asphalt-saturated basemat and fortified with a mix of fiberglass, this product is not only extremely water-resistant, much stronger and more resistant to tears than other types of underlayment.
Does roofing need underlayment?
Underlayment isn’t always necessary, but should be applied to low-sloped roofs, as well as specific high water risk areas of your home. It can also help improve the fire resistance of your home. … In short, underlayment is another key component of your roofing system.
Should I use 15 or 30 pound felt?
If your roof does not have a steep pitch, you can use #15. This weight of felt is a good economic choice if you have a standard roof. But if your roof has a steep pitch, #30 is a better option because it is thicker and tears less during installation. With #30 you get a thicker layer of underlayment and protection.
What is the minimum thickness of roof sheathing?
Roof Sheathing Code Requirements
The minimum requirement for roof sheathing is ⅜” thick. There is no upper limit on how thick your roof substrate is. Thickness allowed depends on how far apart rafters or trusses are spaced and the rating of your roof decking.
What is the minimum thickness of plywood for a roof?
Minimum Thickness
Most roofs will be sheathed in plywood at least 3/8 inch thick. That will suffice on a roof with rafters set 16 inches apart with minimal roof loads.
Is it okay to put new roofing shingles over old ones?
The answer is yes, you can lay new roof shingles over old ones. … You can’t do it with wood or slate, for example, and you should never mix materials, such as laying asphalt shingles over cedar shakes. Also, the old roofing has to be in pretty good condition.
What does a 2 12 pitch mean?
A 2/12 roof slope means your roof has 2 inches of vertical drop for every 12 inches of horizontal distance. Simply put, it’s a shallow roof. That means the roof doesn’t shed water as easily as steeper roofs, which is why choosing the right type of roofing material is so important.
Is roofing felt the same as underlayment?
Sometimes called roofing felt underlayment, roofing tar paper, or roll roofing, this is a layer of protection installed between the roof deck and the roofing shingles.
What should you put under shingles?
Answer: Roofing felt is a layer of tar paper installed beneath the shingles to provide a backup waterproof membrane in case of leakage. Felt, otherwise known as underpayment, is required when asphalt shingles are installed as a first layer of roofing or when they are applied over wood shingles or a built-up roof.