I am about to have some ceiling work done on my house that has previously had roof leaks. I would like to be sure that the repairs to the roof are successful.

How would I go about stress testing the roof? I've considered running a water hose in the known bad spots. Would this be enough to be sure that the leaks are fixed?


If it is a shingle roof, a pressure washer is going to tear it up. Barrel tile is another victum of presure washers unless it is a whole new roof. Old tiles will disintergrate because the bonding agents used to make them grow less adhesive as time goes by.

You should only use you garden hose and let the water run from at least three courses above the old leak, higher would be best though.

What happens most of the time is a simple fix when the roof is first put into place. (Make sure they lap the felt correctly, and do not leave any holes without tar being applied liberally in the right spots, meaning the hole and 4 inches beyond it, then the felt patch and some more tile. They should also slip the top of the patch under the top of the tear in the felt.

Also make sure they are using Simplex nails, not regular thin tabbed nails. Those will suck up much of the time causing a leak to just appear out of no where.

One thing to keep in mind, "Water does not Run Up Hill". in 35 years of construction I have heard that many times on the job and it is crock of Whale snot.

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    A pressure washer with the delicate, or car wash, nozzle on it should not damage a roof. – Edwin Jun 24 '14 at 16:11

To test for leaks, you will need to simulate driving rain for an extended period of time. There are standards that are used to approve building products and methods for water penetration, but it would be hard for you to conduct such a scientific test. Search for "Test Method for Water Penetration." I've seen a documentary about the building of a skyscraper where they tested the assembly of a sample of wall panels. They sprayed water at the seam of the panels at high pressure for an extended period of time. The long duration necessary for the test struck me. I found specifications for such a test here. For your test, you could use a pressure washer with the car wash nozzle attached. Spray a 5 foot section of roof at an angle to simulate driving rain for an extended period of time, about 5 minutes, at a distance of a couple of feet.

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