Have you ever driven by a roofing job in your neighborhood and noticed the black paper on the roof before the shingles were applied? Roofing felt or felt paper, also called underlayment or roofing tar paper, goes between the roof deck and the shingles, which adds another layer of protection to your roof.
Underlayment has a base made from natural materials like wood cellulose, or synthetics like fiberglass/polyester. Then it is covered with a protective asphalt coating, known as bitumen. The felt paper repels water and still allows it to breathe.
Professional roofers know that by adding a layer of protection between the wood and the shingles not only serves aesthetic purposes but extends the life of your roofing. The underlayment serves several purposes: