How to repair a flat roof depends on the type of flat roof you have. We’ll talk about how to repair felt, asphalt, fibreglass and EDPM flat roofs yourself. But ultimately if you want the best finish, it’s best to ask a professional to repair your flat roof for you. Repairing a flat roof Whether you’ve got an old pour-and-roll type felt roof or a newer torch-on felt flat roof, you can get cracks, lifting around joints, leaks or dips. As a temporary measure, you can buy a special paint that you paint over cracks. For a more permanent repair, you can add a patch of torched-on felt or add a layer on top. Asphalt flat roof repair As your asphalt flat roof gets older, you may notice blisters, cracks or shrinkage and sagging around flashings. Again, you can use a paint on fix from a tin as a temporary repair, or add heat-applied flashing tape around flashing. For a more permanent fix you can use a liquid system, but many are only available to the trade market. You can also add a patch of torched-on roofing felt over a crack. How to repair a fibreglass (GRP) flat roof Fibreglass flat roofs are usually excellent, but problems can involve leaking flashing and cracks near upstands, trims or board joints. You can add acrylic sealant to cracks or holes for a good DIY repair, but a flashing problem is more difficult to fix. You’ll need to clean and sand the affected area of flashing, then laminate a 600g chopped strand mat into place, cure it and add a topcoat colour to match the roof. That sounds like a job better left to a specialist. EDPM rubber flat roof repair Rubber roofs often suffer from shrinkage when mechanical fixings haven’t been used near upstands, flashing leaks or holes or cuts. If you’ve got a small tear that you want to repair, you can add some lap sealant to the area – but use it sparingly. For a more permanent repair to flashing, buy some self-adhesive flashing that will mould into shape easily. Clean the area you want to repair, add EDPM primer, then stick the patch of flashing on from the centre outwards with a hard roller. You can add lap sealant around the edges if you want more protection from water.