Flat Roof Repairs Cambridge

Call us on 01223 650685

Every now and then at Cambridge Flat Roofing a flat roof may become leaky. Most of the time however, flat roofs last for many years without any problems. If you live in an area with a lot of snowfall, it is important to have your flat roof checked regularly for damage. Heavy snow can cause the roof to collapse.

If you do have a flat roof that is leaking, there are a few things you can do to repair it yourself. The first thing you need to do is find the leak. This can be done by going into your attic and looking for water stains on the ceiling. Once you have found the leak, mark it with a pencil so you can easily find it when you go outside.

Next you need to determine the type of flat roof you might have.

Bitumen Flat Roof Repairs

Bitumen based flat roofs come in two different flavours:

  • traditional “pour and roll”
  • a more modern “torchon” system

Flat roof pour and roll felting to flat roof

Depending on the construction of the felt, one type or the other may last between 15 and 25 years. There are times when they can be repaired:

Splits and Small Holes in Felt

consider the following roof repair techniques for splits and tiny holes in the flat roof:

Temporary repair

The glue will not be as good as the original product because it is designed to seal wood shingles. However, this version may be used in areas where there are no wood shingles or on roofs that have already been coated with another material. The two layers of Thompson's Roof Seal that we recommend offer the same moisture resistance and strength as the original product, but they do so at a fraction of its cost.

Medium-term repair

If you don't want to use a polyurethane, there are some alternatives. If the surface is dry or clean, apply one layer of cold bitumen followed by a layer of scrim (aka webbing or mesh) for reinforcement before another layer of cold bitumen as a long-term repair. See here and here for examples of cold bitumen and scrim/mesh. There's an instructional video on Youtube that teaches how to repair flat roofs using scrim and sealants.

Long-term flat roof repair

To extend the life of the roof without having to replace it, torch a new top layer (cap sheet) onto the roof. Because this operation necessitates the use of a gas-powered torch, it must be performed by an expert.

Dips and Bowing Felted Roofs

We think that repairs are a waste of time and money if the felt is drooping between the timber supports.

Any repairs would come apart as the roof dips/bows, reintroducing leaks.

It's impossible to save money by repairing a roof in this situation because you have ceiling timbers, decking, and possibly roof boards and plaster beneath the roof. If the major leak is unrepairable, your timber or plaster may be damaged as a result of missing out on an opportunity to replace the roof.

If you want to replace the felt ceiling rather than ripping it down, choose a day with enough sunshine.


The first step in preparing for a new roof is to remove the fabric covering. Check beneath your deck for any missing components and damaged or worn replacement felt before replacing a new one.

Flat roof bowing and bending We’ve heard reports of insurance companies refusing to pay for damage caused by old leaky flat roofs that should have been replaced years ago so if your flat roof looks anything like the one in the photo above, you should really get it replaced

Fibreglass Flat Roof Repairs

Roofs made of fiberglass are generally long-lasting and visually appealing because they lack joints or seams.

One of the most prevalent problems with this material is that it may split.

This is mostly seen on rather huge surfaces, such as double garages, although it can also appear on small roofs like those found on porches.

Furthermore, the good news is that repairing fibreglass is straightforward.

All-in-one fibreglass repair kits start at around £30 and take less than an hour to fill in a hole, split, or crack.

There are a slew of instructional films on Youtube, however the process is as follows:

  • clean area thoroughly
  • sand with a coarse sandpaper
  • clean with acetone
  • chopped strand matting is then laminated into place
  • after its dried, a top coloured layer is applied

Check out this product on Amazon.

Mastic Asphalt Roofs

This is a costly flat roof that should endure for decades.

It's regarded by many in the business as "the Rolls Royce" of flat roof materials.

Unfortunately, because it isn't very flexible and is quite hefty, any movement of the roof beneath may result in fractures and cracks.

Mastic asphalt flat roofs can crack for a variety of reasons.

  • After applying the new layer of mastic asphalt, it's possible to add an extra layer of mastic asphalt on top - this should be done after reinforcing the area around the fracture to prevent it from leaking into the current layer.
  • A surveyor's tarp, often called a "torch," may be used to repair or cover the whole roof in bituminous felt. If the look of this felt is a problem, it can be covered with a grey/silver reflecting paint as well as the rest of the roof.

EPDM/Rubber Roofs

A rubber roof, also known as a "rubber dome," is easy to put up and doesn't need a gas-powered heat torch.

While the material itself is long-lasting, weak points are often discovered at the joints and upstands.

Small holes, rips, and tears can all be readily repaired by using one of the following adhesives:

  1. A rubber sealant like this Firestone sealer can be used to fill short-term gaps. However, for tiny holes, it may last a long time.
  2. However, this method of replacement is not recommended by the manufacturers; instead, they recommend that you use an insulating sealant such as Firestone flashing tape. This is a long-term solution and should outlast the roof.
We also repair and fit flat roofs in the following local areas:

Reviews and Testimonials

We recently had a flat roof installed and have been thrilled ith the service we have received.
Jack Harvey
We'd been messed around by our previous roofing company. The team were punctual, clean and tidy and transformed my leaking garage roof.
Susie Langston
These guys worked quicly on our new rubber flat roofing. The job was completed quickly and efficiently
Jonny Chartwell
flat roof
t. 01223 650685
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