How To Maintain A Flat Roof

How To Maintain a Flat Roof
For those homeowners who want to know how to maintain a flat roof, the advice is straightforward though there will be potential worries over whether you should buy a house with a flat roof in the first place.

Lots of homebuyers will be reluctant to buy a property that either has a flat roof or has a garage or extension with one because of the maintenance issues.

However, if it has been properly maintained then you should not be reluctant or nervous about buying the property.

Firstly, it’s important to ask the home seller whether they have maintained it effectively and a full survey will highlight any potential issues – this survey could be invaluable if the surveyor raises any potentially expensive issues.

Insuring a property that has a flat roof

In addition, you may find that many home insurance firms will be reluctant to insure a property that has a flat roof over worries about the ongoing necessary maintenance – and whether the previous owners have left behind a problem because they failed to maintain it properly.

You may also find that as a home buyer that you need to use a specialist non-standard home insurance broker to provide relevant insurance coverage for your home.

Flat roofs can have a long lifespan, but they need to be correctly maintained to do so and they tend to be made from felt, asphalt, GRP fiberglass or EPDM rubber proofing.

Along with putting flat roofs on garages and extensions, there may be other reasons why one has had to be constructed since planning regulations may restrict a pitched roof if it will obstruct a neighbour’s view or light, for example.

Also, a property extension may have to use a flat roof if it butts up to the building itself. In some properties, old asbestos coverings have been replaced with modern flat ones.

Common problems for a flat roof

Flat Roofs demand special care

So, what are the common problems for a flat roof?


The big worry about a flat roof is they may not be correctly maintained and have a short lifespan.

The lifespan will depend on the materials being used with asphalt and felt-based coverings being less durable when compared to modern materials such as EPDM.


Felt flat roofs are prone to splitting, ponding and blistering.

Splitting occurs when it has not been maintained properly or it has been damaged, for example, with someone walking on it. The splitting is caused by pressure, stress, poor workmanship and thawing.

Ponding is an issue when there are standing pools of water that do not dry out or drain away. Sometimes, you may need a pump that will work automatically in problem areas or look to fit drains or carry out repair work to prevent ponding issues.

Blistering occurs when the air becomes trapped between the felt layers. As this air warms up, it can lead to a puncture or blister appearance that may then split. Should this blister occur on a join then water is able to pass through the roof. Blisters should be fixed professionally, so the seal is maintained.

Protect and maintain flat roofs effectively

While we’ve covered the main problems, there are steps that homeowners can take to protect and maintain their flat roofs effectively. These steps will include:

  • Maintenance

To prevent your flat roof from being damaged, then maintenance must be carried out on a regular basis, at least every autumn and spring and you will have to carry out an inspection following any heavy weather conditions.

Regular maintenance is crucial for a healthy roof
  • Hire a specialist

A professional will ensure your flat roof is maintained properly by removing dirt as well as debris, drain sand gutters regularly.

It’s important to appreciate that unless your flat roof has been designed specifically for use as an outdoor area, then it’s probably going to be fragile when someone stands on it. This may affect the rain run-off and create punctures and blistering.

Maintenance also extends to areas around the covering, so you will need to cut back overhanging branches to avoid damage and blockage from fallen leaves.

  • Bad weather

As mentioned earlier, you will have to check for any damage after poor weather, particularly after snow and ensure it is cleared away carefully. Snow can cause significant damage and if water or snow freezes, there when it thaws it’s liable to split the surface.

  • Check the ceiling

Maintaining a flat roof properly is not just about inspecting the exterior and you should check the ceiling regularly for any stains that may be caused by water damage. If you do spot water stains, then you need to act quickly to prevent more damage occurring.

Questions about flat roof problems

There may be other questions about flat roof problems that may not have been covered and here we will explain more:

How long do flat roofs last?

A flat roof will usually have a warranty of between 10 and 20 years, but if they are properly installed by professionals and then maintained effectively they can last for 25 years. If it is made with EPDM then the rubber has a life expectancy of up to 50 years, and in some cases can last longer.

How often should you seal a flat roof?

Regular maintenance will be key to ensure it does not leak and will last. You could hire professionals but it is also possible to buy flat roof coat seal from DIY stores to do this work yourself. It will need repairing when there is an issue and resealing.

How often you’ll need to seal a flat roof depends on a number of factors including how exposed to the elements it is, whether it is south facing, and what type of sealant you used previously. Typically most should only need resealing every 5 years or so.

Does moss damage a flat roof?

Yes, moss damages your roof

The short answer is yes, moss can damage a flat roof. Indeed, any unwanted vegetation or growth will highlight that water is being held on the roof to enable moss to grow and it will, ultimately, lead to leaks. You also need to appreciate that moss will increase the weight and could lead to sagging joists and split the covering.

Can flat roofs be repaired?

Yes. There may be a range of issues from the simple replacement of the felt, though, if there are problems with the joint joists or membrane, then it may lead to a bigger job or a complete flat roof replacement.

Flat roof maintenance costs

It costs nothing to carry out regular maintenance, such as cleaning and removing debris from gutters. The price of sealant starts at £5 for a small tin if you want to do the work yourself.

For those who need a new flat roof and use the current structure, then the cost will range from £800 – £1,200, this is for the price of a typical single garage size using modern products including rubber EPBM.

Flat roof gravel

Some flat roofs will have a gravel coating which plays two important roles. The first is to weigh down the covering surface and the second role is to protect it from sun damage.

Traditionally, a flat roof will be made watertight and the gravel will keep it weatherproof. You could use professionals or carry out the repair yourself using tar and gravel repair kits from a DIY shop.

Flat roof protection

The flat roof will need surface protection to help protect it from the sun’s rays but also from the thermal movement since the roof will expand in hot weather and also differential movement – that’s when it is warmer than the structure below it. Under building regulations, there will be a need for fire protection and this is specified to help control the spread of any flames.

Flat roof shingles

As with gravel, flat roof shingles, sometimes known as pea shingle flat roofs, provide a loading coat and help to protect the surface from sun damage.

The shingle needs to be properly bonded to the surface material and it cannot be scattered across the roof. Done properly, a shingles’ prepared flat roof will provide a surface that will last for many years – when it has been badly done and shingle is loose it’s a sign of poor quality work.

Repair work on a flat roof

Along with carrying out any repair work on a flat roof yourself, you could hire a professional, but you should:

  • Ensure that they specialise in this particular type of construction
  • Have them give a fixed cost quote
  • Check they have insurance for carrying out the work
  • Have a written estimate of how long any repair work will take
  • Ensure that any work carried out is done under a warranty or guarantee.

Essentially, if you fall in love with a property but are worried about the problems that may arise from having to maintain a flat roof, then it’s crucial that you have a proper survey done to ensure that it has been cared for properly. Then make sure that you carry out maintenance checks at least twice a year and undertake any repairs that need doing immediately.

Further information:

Confederation of Roofing Contractors

National Federation of Roofing Contractor

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