Flat Roof Repair DIY Instructions

Flat Roof Leaking? Not sure whether it can be repaired or needs to be replaced entirely? If you willing able to climb a ladder yourself, here’s how you can check what’s causing your flat roof to leak yourself, and make a decision on whether to repair it, or replace it. If funds are tight and you’re willing to have a go yourself – here are basic DIY instructions to fix a leaking simple flat roof:

  1. Check your flat roof covering for obvious signs damage, e.g. of holes, cracks at roofing material joints and the flashing around the roof edges. The location of the leak below may not necessarily be located immediately above where the water leak appears. Rainwater often circulates between roofing material layers and moves laterally rather than draining vertically.
  2. You need to remove and replace all damaged top layer roofing material. Once the top layer is removed, check the boards below the damage. Rainwater that has pooled between the top layer of roofing material and the boarding will cause the boarding to rot. If the boards are rotten, they must be removed and replaced with new boards.
  3. Before replacing with new boards, thoroughly inspect the timbers below any rotten boarding. If the timbers are still good – carry on. Otherwise replacing the timbers becomes a much bigger, structural repair job and not a candidate for a DIY repair. Time to call in the professionals.
  4. If the timbers are not rotten, now is a good time to replace any wet insulation material, or add new insulation where there may have been none in the past. Lay this between the timbers. We can advise on the best choice and depth of insulation materials.
  5. Next, lay new plywood to replace rotten boards. Some basic carpentry skills and tools will be needed for this. Speak to your local building merchants or call us to advise on the best choice of material – i.e. quality, depth and type as there’s a lot to choose from e.g. marine ply.
  6. Now lay the first layer of 4mm felt roofing material accross all areas being replaced, sealing the joints and edges as you go. Pay particular attention to where theflat  roofing material adjoins flashing – replacing this if necesary.
  7. Finally lay the top layer of mineral felt roofing material, ensuring the joins are not directly over the joins of the first layer of mineral felt. Again, pay particular attention to sealing all edges and joints – especially around edge flashing.
  8. Well done! You’ve completed your flat roof repair and if done properly will serve you well for years to come. You deserve a cuppa now 🙂

If this sounds complicated to you, especially if your roof has a chimney, vents, velux windows or any other structure punctuating the roof which will require specialist flashings being installed, don’t attempt it yourself.

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A leaking flat roof may be caused by a number of things, often in combination, such as poor quality, rotting, building materials or just plain bad construction. If water tends to ‘pond’ in the middle of your flat roof, this may indicate that the roof structure has deteriorated beyond it’s natural bending point and no longer drains water properly. This is a clear sign that you need to replace your leaking flat roof altogether, in which case you would be better to call in professional roofers such as 1st Roofing Edinburgh on 0131 440 2525 or mobile 07894 810070, who can advise you on whether your flat roof can be repaired or if it is so far gone that it needs a complete replacement to fix your leaking flat roof once and for all.