Waterproof Test

Mariya, a homeowner in Washington D.C., had this question:

Can you do a water test over just the waterproof membrane, prior to installing shingles?

Marty Stout from Go Roof Tune Up had this to share:

There is no reason to do a “water test” on underlayment for a shingle roof. The underlayment alone for shingles is not a water proof system. And when shingles are installed about 400 nails per 100 sq. ft. of roof area will be driven in the underlayment. On a shingle roof the shingle alone is what sheds the water, the underlayment is installed as part of the system mostly to serve as a buffer between the shingle and sheathing.

Thanks for your question! Your Friends at AskARoofer

I think there is no need to test the waterproof capability before installing shingles. The shingles normally have water-resistant property