More than 12 years ago, I wrote an article on peel-and-stick window flashing. The article, “Choosing Flexible Flashings,” appeared in the June 2001 issue of The Journal of Light Construction (JLC).
My article surveyed a variety of peel-and-stick products, including products with butyl adhesive as well as products made from rubberized asphalt. As part of my research, I interviewed industry experts to find out more about the strengths and weaknesses of these materials. I also interviewed builders about their job-site experiences with these products.
Back in 2001, I obtained samples of 21 brands of peel-and-stick flashing and performed a backyard test. First, I built a small wooden “bathtub.” Then I drilled a series of 7/16-inch holes in the bathtub and patched each hole with a sample of peel-and-stick. All of the samples were numbered. Fourteen hours later, I filled the bathtub with water.
I hoped that this backyard test would tell me whether peel-and-stick flashing is really waterproof.
So what were the results? One minute into the test, the first of the 21 brands of peel-and-stick showed signs of leakage. Six minutes into the test, four more products began leaking. After 20 minutes, 12 of the 21 tested products were leaking; then the situation stabilized. The 12 leaky products continued to leak, while the remaining nine products appeared to stay watertight. After 45 minutes, I discontinued the test. (For the record, the nine tapes that didn’t leak were Sealtight Air Shield, Dur-O-Wall Polytite PolyBarrier, Vycor Plus Self-Adhered Flashing, NEI AC Homeseal Self-Adhesive Membrane, MFM Building Products Sub Seal 40, Protecto Wrap BT20XL Building Tape, Ridglass Kwikwrap, Sandell Presto-Seal, and International Diamond Systems Tape Flashing.)
I discussed the results of the test with my JLC editor, who decided that the test wasn’t scientific enough to report. In the published article, I alluded to the test without reporting the individual results:…