Roofing felt prevents the deck from being exposed to the elements before or while the shingles are being applied.
How to install tar paper on a roof.
Some roofers prefer to attach felt underlayment with 1 inch roofing nails or special nails with plastic washers but most codes allow staples which are easier to drive.
The idea is to make sure water that falls on the roof drips down from paper to paper and off the roof rather than up under the tar paper potentially damaging the roof s wooden structure.
Whether you re building a new house or putting a new roof on your existing house installing tar paper first helps waterproof the roof and prevent leaks.
Before applying roofing you ll need to cover the sheathing with roofing felt also often called tar paper most local codes call for using 30 pound felt.
It improves look and uniformity because your roof deck might not lie perfectly straight or flat a layer of roof paper gives an even uniform surface upon which you can install your shingles.
Unroll the paper on the roof and cut it to the correct length with a utility knife.
How to install roofing tar paper.