How to Fix a Damaged Flat Roof

For homes and buildings with a flat roof, you might be concerned about how you will replace this type of roof in the future. Our team of roofers in Buckinghamshire and South London are highly experienced at flat roof replacement and will be here to guide you through the process from start to finish. Let’s take a look at everything you need to know about flat roof options and materials to support this process. 

1. How to Locate Damage to a Flat Roof
First step is to locate where the roof damage has originated from. For example, if you have a leak then determine how far the leak is from the 2 closest walls. ​Finding damaged areas on a flat roof can be tricky because the water tends to drip some distance before you see it. It's best to wait at least 72 hours from when the leak has dried up, preferably in the evening. Temperatures drop at night, so heat will be released from underneath your flat roofing meaning that it will gently steam. 

To get an estimation of where leaks stem from, go inside your home. Find spots that look wet or discoloured from water damage, then use a tape measure to determine their relative positioning under the roof. In particular, look for any low spots with rings of dirt, which indicate pooling water was there before.

2. How to Temporarily Fix a Leaking Flat Roof
Putting in a temporary fix is great if you need to buy yourself some time, you can use this time to pack away any possessions to keep them from getting damaged. The best way to do this for a leaking flat roof is to use waterproof paint to seal over the area. It's best to check that there are not other areas contributing to the leak, otherwise this method will be pretty useless and make things more complicated for you in the future.

3. How to Properly Fix a Flat Roof
You should not attempt to climb up or out onto your own flat roof. This is incredibly dangerous and is a reason for why we exist! We highly recommend calling our roofing specialist team to come and investigate any slope areas, punctures, tears or cracks. Based on the type of damage, we will look to either seal cracks or holes, apply roof patches, reseal the roof or replace it completely (depending on the level of damage). 

4. Different Ways to Repair a Flat Roof
The most common types of flat roofing we see are; Fibreglass (GRP), Rubber, Felt and Concrete. Felt being the most popular in the UK. Felt is great for roofing as it's cost effective and easy to install. That being said, it has a high risk of damage and especially leaks. 

In terms of repairing a felt roof, it depends on the type you have and what the damage is. It's common to see split felt, lifting joints, impact damage, broken flashings or fissures in the surface. As it is a cheap roofing material, it's best to replace the entire roof. This will save you money in the long run, otherwise it's very likely you will have to constantly repair it over time.

The best way to repair a felt roof leak is to use acrylic-based waterproofing paint. This is a really effective method and works well on split felt and lifting joints. However, if your flashing is retreating then we would recommend redressing it to restore the waterproof seal. Long-term we would recommend using a patch of torch-on roofing felt, or adding an additional layer to your felt roof. This is something our experienced team would take care of as it can be highly dangerous due to hot flames.

5. How Much Does it Cost to Repair a Flat Roof Leak?
The exact cost of repairing a leaking flat roof will depend on the size of the problem. If you’re looking to undertake a full flat roof replacement to repair the leak, that could cost you anywhere from £200 to over £1000 depending on the size of your roof.

Need your flat roof looked at? Call us on ​020 8144 9985.