Tar paper

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Tar paper is a heavy-duty paper used in construction. Roofing felt is one type of tar paper. Tar paper is made by impregnating paper with tar, producing a waterproof material useful for roof construction. It is sold in rolls of various widths, lengths, and thicknesses (3 foot wide rolls, 50 or 100 feet long and "15 lb" and "30 lb" weights are common in the U.S.), often marked with chalk lines at certain intervals to aid in laying it out straight on roofs with the proper overlap (more overlap for flatter roofs). This bitumen based material is sometimes applied in several layers with the help of a torch and additional hot tar, but is more often applied with staples or roofing nails and used as underlayment for asphalt, wood(a.k.a. shake), or other shingles, or even gravel, since tar paper itself isn't particularly wind- or sun-resistant. More modern roof waterproofing materials include PVC and TPO (thermoplastic polyolefine) membranes which provide increased protection against leaks.

Older construction sometimes used a lighter weight tar paper, stapled up with some overlap, as a water- and wind-proofing material, but modern construction uses 8 or 10 foot widths of "Housewrap," one brand of which is Tyvek, which is extremely durable and wind- and water-proof since there are far fewer seams than with the 3 foot wide rolls of tar paper.