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Common Problems with Fibreglass Roofing

There are some common problems with fibreglass roofs. We are going to assess some of the common problems you may have with your fibreglass roof. Fibreglass roofing is sometimes known as GRP roofing. GRP stands for ‘Glass Reinforced Plastic’. In has become one of the most popular flat roofing choices in the UK.

Common Fibreglass Flat Roof Problems


Fibreglass Roofing has extremely good waterproofing properties compared to some other flat roofing systems. Despite this the pooling of water can still occur on GRP roofing and lead to leaks. If you notice large pools of water or patches of a darker or lighter colour than the rest of your roof with a dirt stained ring you should contact a roofing professional as soon as you can to save more serious problems developing.

Flaking or cracking

Sometimes the top coat can start to flake and crack. The normal cause of this is if applying the topcoat too quickly or applying the topcoat on top of the laminate whilst it is still wet.

The way to fix the issues of flaking and cracking on the surface of your roof is by replying the topcoat.


Every roof has its life expectancy. Fibreglass roofs can last for 50 years. When a GRP roof does reach this age, it can lose its elasticity. The result is the roof becomes to looking wrinkled and cracked like the skin of an alligator. This is where the term alligatoring comes from. If you spot this problem on your roof in most cases the solution will be a roof replacement.


All roofs can be susceptible to problems if they are not maintained in the appropriate manner. GRP roofs are no exception to this. Gutters on flat roofing are more prone to gutters become blocked. To prevent gutter problems, it is advisable to have maintenance carried out on a regular basis this will involve cleaning out your gutters and roof sweeping. By regularly having maintenance work carried out you will prevent water builds up occurring which can lead to leaks.


A fibreglass roof can sometimes develop extremely small pinholes on the surface. The reason for this is insufficient resin being used during the installation process. This problem can deteriorate over time and lead to leaks.

The way this problem can be fixed is by key sanding the roof and ensuring the proper amount of top coat is applied second time around.

Holes or Splits in the Surface

Occasionally splits or holes can appear in the surface of a GRP Flat roof. If the wood underneath the fibreglass roofing remains dry this can be fixed by a roofing contractor re-applying the fibreglass once more. Once this in place your roof should be in working order again. However, if the wood below your roof is not dry a roof replacement may be needed.

If you are experiencing any difficulties with your GRP Fibreglass Roofing and are in the Woking or Guildford area Raynes Roofing would be delighted to help you. With over 45 years’ experience we will be able to quickly diagnose your problem and advise you on the best way to dix your problem just get in touch today or call us on 01483 475141.