Liquid-applied flashings are caulk-like materials that are spread with a trowel. Once cured, these products form a waterproof, airtight, vapor-permeable layer that can prevent air leakage through sheathing seams or protect rough window sills from water entry.
After I wrote my recent article on liquid-applied flashings, I decided to conduct a backyard test of these products. Like the backyard tape test that I conducted in 2012, this test wouldn’t be scientific (because I lack the financial resources required for a scientific test). Although the results would never be published in a peer-reviewed journal, I hoped that noodling around in my back yard might nevertheless reveal some useful information.
My test consisted of the following steps:
- Step one: I rounded up seven products.
- Step two: I built a test rig.
- Step three: I installed the seven products on the plywood seams of my test rig.
- Step four: I exposed the cured flashing products to the weather for a month.
- Step five: I sprayed the test rig with water from a garden hose for 10 minutes.
- Step six: I flooded the test apparatus so that the cured flashing was under a 2-inch layer of standing water.
I tested seven products, each with a distinctive color:
Building a plywood test box
I decided to use a sheet of 1/2-inch CDX plywood as my test rig. I reinforced the plywood sheet on the back with four 8-foot 2x4s, 16 inches on center. Once the plywood was screwed to the 2×4 frame, I cut seven 4-foot long kerfs right through…