Bostik Flashband Self Adhesive Flashing Tape for Roofs Grey - 100mm x 3.75m - Provides an Instant Watertight Seal - Complete With Primer

Did the job well.

The ceiling had been leaking upstairs for months. One day the plasterboard gave way to reveal a false ceiling and a previous collapse due to flood in the original plasterboard. Found a local roofer who accepted monthly payments, and he came round twice, once to inspect the roof and put up a temporary repair, and the second time to do a full one. The temporary repair lasted three downpours, which wasn't bad. He came round on the appointed day a week later and claimed to have replaced the entire first level of underfelt. It survived four downpours over the next week or so, and I began to repair the ceiling with spare plasterboard and filler. A week after the repair (but before painting, leaks appeared in the same area. He refused to even check his repair until I paid the second instalment. I told him to get lost, and he cancelled the contract having received one instalment. The neighbours had leaks of their own, and found a different roofer who let me use the scaffolding. I bought the tape in anticipation, and went onto the roof expecting to repair underfelt. I found a crack of about 8 inches in the lead wihich my roofer hadn't spotted despite him sweeping away years of moss from the gulley. I removed a few tiles to access the end of the crack, and discovered that my roofer hadn't replaced the underfelt as claimed. He simply placed a small piece of 'something' over where he had found a hole which he assumed was the source of the leak. The original underfelt is clearly showing. Anyway, I applied the primer which is supplied with the tape, and left it to dry. The fact that it was starting to drizzle makes no difference, as you apply the primer with a wet brush. I put lots of it in the crack and surrounding area. We then had a storm that included hailstones which lasted more than an hour. Not a drop of water came through the ceiling, and that was without the tape. Next morning, armed with heatgun, roller, sharp knife, I applied the tape to the repair. I heated a strip to facilitate the removal of the protective tape, and then placed it bitumen-side down over the crack. I used the heat to soften it further, all the time using the roller as advised. I put three pieces down as a belt and braces measure, knowing that the primer had already sealed the crack. This was done for extra weather protection. It has since rained gently once for about 10 hours, and there isn't a damp patch in the attic above. I also put some on some lead flashing against brickwork that didn't leak, and found that it welded to both surfaces. Time will tell, of course, but initial results lead me to recommend this product highly.

I used this to repair splits in our roofing felt. The first repair has lasted, but the second hasn't. I repeated the failed one and have had to secure a batten to hold it in place. My conclusion is they are sufficient for minor jobs, but the adhesive is not substantial enough for larger works.

Bought after being recommended to repair some splits in my lead flashing. Did the job on a very hot, sunny day & even though I was on a ladder, it was an easy task that seems to be standing the test of time, been there for over 18mths now & has blended in with the original lead pretty well so as to be barely noticeable. One of the splits was wider than the instructions allow for too.

Probably old stock r poorly stored. There is almost NO adhesive quality, it's not even tacky.