Roof Felt 15 Lb Vs 30 Lb

Felt roofing underlayment is typically available in two types.

Roof felt 15 lb vs 30 lb.

Fifteen pound felt has a perm rating of about 5 although this number can rise in high humidity conditions. Felt is an asphalt saturated organic felts designed for use as an underlayment with asphalt shingles in commercial and residential applications. A shingle underlayment is used to protect roof structures and the interior from water penetration. Roofing felt comes in large rolls and installs in horizontal rows starting at the lower edge of the roof with each subsequent row overlapping the previous one.

30 was used as a base sheet for built up roofing and underlayment under slate tile and shingles. The difference is obvious once you see them together. No 15 felt and no. The main advantage of using felt roofing underlayment is cost.

30 pound gets to oily in the summer and smears to easily. In the old days common felt was 15 lb felt and 30 lb felt and a roll of the first held 4 squares and weighed 60 lbs while a roll of the second held 2 squares and weighed 60 lbs. 30 felt is typically thicker stronger and may be less prone to tearing or ripping off during installation or weather events. Twice as much work carrying paper with 30 too.

Plywood or osb roof deck so 15 20 or 30 will work for any shingle roof the type i recommend depends on roof slope. Because it s thicker and stronger. 15 pounds with enough tacks or boards is plenty good enough. 15 came perforated for use as a ply sheet for built up roofing use and non perforated.

In my opinion felt paper is a vapor barrier plus keeps the oils in the shingles from leaching out and into the wood substrate i e. Preparation sweep roof deck to remove. Felt description united 15 lb. The best weight for roofing felt is the 30 pound product because it provides thicker and stronger footing for roofers that does not tear out especially on steep roofs where footing is critical.

Thirty pound felt is more resistant to damage during installation of the roof covering material and will protect the roof longer if it should somehow become exposed to weather.