Q & A - Roofing Felt, How Long Can I Leave It Uncovered?

Al asked, "How long can I leave the roofing paper uncovered?"

Roofing Felt is applied to the deck with roofing nails and under steep slope roofs like tile, shakes and asphalt shingles. When re-roofing it is common to feel a roof out and leave it when rainy weather is present. This, when having all the protrusion flashed is a pretty watertight roof as long as there are not high winds that could blow off the felt. In new construction, tile roofs are prepared with felt and battens and left for many weeks as the different trades complete their work without risk of breaking fresh new roof tiles. The manufacturers approve of this application with different time allowances.

I hate to leave felt more than a month in the summer. The felt is saturated with waterproofing that can start drying out causing it to curl. This short time doesn’t really hurt the felt but the curly up of the edge can cause trips and falls which is not good on rooftops.

This is a picture is a job I contracted in 2003 in Roseville California. Kinda hard to believe but I installed these roofs here 23 years before. It was done in the spring and weather was an issue. The total job was 1,050 squares of heavy cedar fire-rated shakes. This is a #30 felt 22 inches wide to provide a double felt installation. On asphalt roofing #30 is recommended but #15 is commonly used both being 36 inches wide.

Interestingly many years ago when I worked for another contractor a shortage of two bundles of shakes got forgotten on a residential roof. Two years later it was discovered only because the owner was up on the upper story installing an antenna. No leaks but it looked weathered.

I hope this answered your question. 

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