Here are the layers of a roof in order of application bottom to top.
Two layers of felt on roof.
You can cover the surface of the felt with gravel for added strength.
Five best practices reasons for using roofing felt underlayment.
Apply another layer of adhesive to the top for maximum waterproofing.
I have been supplied with way too much felt.
This will help the two layers adhere to each other.
Wind driven rain or snow can trap water under your shingles putting your roof deck and inner residence at risk of moisture.
Add the second layer.
On roof slopes of 2 12 to 4 12 the remainder of the roof shall be two layers of 15 felt applied in shingle fashion or 1 layer of ice dam protection.
The key to weatherproofing your flat roof is adding a total of 3 layers.
So anywhere along the gable end that you can see the felt you ll see two layers.
You will follow the same process as in step 2 for the last layer.
If i were you i d at least follow up with that roofer on why they chose to spec 2 layers felt just for piece of mind and in case he turns out to be the better roofer or not.
It didn t come with any underlay but i have worked out i could felt the roof twice with the cap sheet felt they have supplied.
In northern climates ice or snow dams are another common.
Thus you will repeat the earlier steps.
It provides structure by tying.
Saving on the initial shingle installation doesn t solve the long term cost of adding a second layer of shingles.
I am aware of the best practise of at least one layer of underlay nailed to the deck before a cap sheet is glued to the top with cold adhesive.
It provides backup protection in the event of ice or water damage.
Most often made out of plywood this roof layer is installed over the framing in a typical roof install.
Cover the edges of the roof with strips of felt before laying out the final layer.
Assuming your roofing contractor is using standard 36 wide 15 roofing felt double coverage means that each layer of felt put down across the roof laps 19 over the upper half of the previous course.
The first course starts with an extra 1 2 wide run.
For decades roofers have fitted a layer of felt over a roof s sheathing or roof deck before installing shingles.
Before adding the second layer though spread a thin layer of adhesive on the first layer using your trowel.
Why use roofing felt paper.
Two layers of shingles trap more heat which in turn damages the shingles and shortens the life span of the roof.
