How to repair a split in a single-ply roof with Supraseal®

A split in a single-ply membrane is one of the most common flat roof leaks, and one of the easiest to fix properly. Supraseal® is a butyl-based, bitumen-free tape that bonds to EPDM, TPO and PVC membranes, so you can make a permanent repair in minutes, cold applied, with no torch and no liquid.

What you'll need

• Supraseal® weatherproofing tape in the right width (see which width do I need?)
• A sharp knife or scissors
• Clean cloths and a suitable membrane cleaner
• A silicone seam roller, or firm hand pressure if you don't have one
• A tape measure

Watch the technique

Step 1: Find the whole defect

Water often travels under a membrane before it shows inside, so check around the visible split for any further damage. Mark out the full length of the split and any nearby punctures. It's usually quicker to cover them in one patch than several.

Step 2: Clean and dry the area

This is the step that makes or breaks the repair. Remove dirt, moss, gravel and any loose coatings from an area well beyond where the tape will go. Clean the membrane with a suitable cleaner, then let it dry completely. The tape will not bond reliably to a wet, dusty or greasy surface.

Step 3: Measure and cut

Cut a length of tape that runs at least 50mm past each end of the split, and choose a width that gives at least 50mm of overlap along both sides. Round off the corners of the patch with scissors. Rounded corners are far less likely to catch and lift than square ones.

Step 4: Apply from the middle out

Peel back a short section of the release liner and position the tape centrally over the split. Press it down, then keep peeling the liner as you work outwards, smoothing the tape from the centre to the edges to push out any trapped air. Don't stretch the tape as you lay it.

Put it down slightly wrong? Supraseal® can be lifted and repositioned within the first few minutes, so take your time to get it straight.

Step 5: Roll it in firmly

Go over the whole patch with a seam roller using firm, overlapping passes, paying extra attention to the edges and any lap where the tape crosses a seam. Firm, even pressure gets the butyl into full contact with the membrane. The bond starts working straight away and keeps getting stronger over time.

Step 6: Check the edges

Run a finger around every edge. If any section is lifting or has a wrinkle, press and roll it again. On high-stress details such as external corners, add a second layer of tape over the first for extra protection.

Finishing touches

• Supraseal® is UV stable, so it can be left exposed. It can also be painted over if you want it to blend in.
• Work in dry conditions. In cold weather, store the roll somewhere warm before use so it's easier to handle and grabs faster.
• Take a photo of the finished repair for your records or your customer.

Need help with a tricky detail?

Upstands, outlets and corners each need a slightly different approach. Email hello@supraseal.com with a photo and we'll talk you through it.