Can you apply flashing tape in cold or wet weather?
Most roof leaks show up in autumn and winter, which is also when conditions are worst for fixing them. The good news is you don't have to wait for summer. A butyl flashing tape can go on in cold weather if you handle it properly. Wet is a different matter.
The short answer
- Cold: yes, with care. Warm the roll first and roll the tape on firmly.
- Wet: no. Tape won't bond to a wet, frosty or dewy surface. Dry the area first or wait for a dry spell.
Why cold makes tape harder to apply
Butyl adhesive gets firmer as it cools. A cold roll feels less tacky, and the tape doesn't flow into the texture of the surface as readily, so it takes more pressure to make full contact. Once it's on and bonded, though, cold isn't a problem. Supraseal® stays flexible down to -30°C in service, and the bond keeps strengthening over time.
As a general rule across the industry, self-adhesive flashing tapes are applied to surfaces at around 5°C and above. Below that, you're more likely to be fighting frost and condensation than the tape itself.
How to apply tape in cold weather
- Keep the roll warm. Store it indoors overnight and carry it in an inside pocket or a warm van cab until you need it. Only take out what you're about to use.
- Pick your moment. Late morning to early afternoon is best, once any frost or dew has gone and the sun has had a chance on the surface. Avoid the last hour of daylight, when dew starts forming again.
- Check the surface by hand. If it feels damp or greasy, it is. Wipe it with a dry cloth and look again a few minutes later. If moisture comes back, it isn't ready.
- Clean it properly. Moss, algae and dirt hold water. Scrub them off and let the area dry.
- Cut shorter lengths. Shorter pieces are easier to handle when the tape is stiff. Overlap joins by at least 50mm.
- Roll harder than you would in summer. Pressure is what makes the bond, and in the cold you need more of it. A seam roller gives far better contact than a thumb, especially at the edges.
What about wet weather?
No adhesive tape bonds properly to standing water, ice or a film of condensation. If it's raining, you have two options:
- Get it dry and tape it straight away. On a small area, once the rain stops, wipe the surface with a dry cloth and dry it off with a hot-air gun on a low setting. Then tape it before it gets wet again.
- Make it temporary. Weigh a tarpaulin down over the area (don't nail through the roof) and come back on the next dry day.
Tape that's put on a damp surface might look fine for a week. Then the edges lift, water tracks under them and you're back where you started.
Stay safe
Cold, wet roofs are slippery, and the days are short. Don't go up a ladder in wind, ice or failing light, and don't work on a roof alone. If the leak is high up or the roof is fragile, get a roofer.
Which tape to use
Supraseal® Weatherproofing Tape is a cold-applied butyl tape that seals in minutes with no torch, and can be repositioned in the first few minutes if you get it wrong. It's UV stable, bitumen free and backed by a 10-year warranty. Not sure which width you need? See our width guide or try the tape finder.