Rain On Tar Paper Roof

Traditional roofing felt also called tar paper or underlayment is felt saturated with bitumen also called asphalt.

Rain on tar paper roof.

Bitumen or asphalt is distilled from petroleum and is what makes roofing felt waterproof. Over a long and i mean long period of time the sun heat will dry out the. When tar paper gets wet it buckles and ripples. Certainly it would have been better to have covered the roof with a tarp or roofing felt before it rained.

Felt is compressed fibers of wool. The top is protected from the sun by stone granules but there is no such protection on the underside. It sounds like the tarpaper covering this is the old tar paper correct. Normal delays and the rain you indicated will not affect the structural properties of the panels.

When shingles are placed on top of rippled tar paper voids are created which act as little greenhouses that collect heat and break down the shingle from the underside. Our osb is rated exposure 1 and that means that it will withstand normal delays in construction. It is typical for the roof to be in this condition for 30 60 days while other phases of the construction are completed. I wouldn t trust it in the rain but it s not my job.

Osb like all other wood will expand. Any repairs would be his problem.