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Maintain or Repair a Flat Roof

As one of the most cost-effective ways to add on an additional room, building with a flat roof design reduces the cost of additional roofing materials and labour costs. Roofs on low angles and roofs on flat surfaces, by the very way they have been designed, are usually waterproof. But shoddy workmanship on existing flat roofs and over time these roofs can be a big problem.



No matter the type of roofing, leakage and flashing wear will always be major concerns. Leakage, can occur once the roof is no longer as watertight as it ought to be, and can cause further damage by adversely affecting insulation, roof framing, and interior surfaces. Homeowners should look at replacing a low-slope or flat roof as deterioration becomes evident, such as blistering, bubbling, and cracking of the membrane, and separation at the seams.

Flat roof designs in South Africa are often constructed from corrugated metal, fibreglass sheeting or concrete. The first two are constructed with a slight slope to allow water to run off but the flatter - a flat concrete roof - is prone to leaks unless properly maintained. In order to prevent roof leaks and water leaking into your house with a flat roof, the entire roof must have a layer of watertight seal.

There are various methods of waterproofing a flat, concrete roof with the most popular being a membrane coating, often covering a rubber coating. Good waterproofing will increase the lifespan of your flat roof, and reduce the amount of maintenance that needs to be carried out over time, hence the reason why a flat roof should never be neglected.





Maintaining a flat roof

Maintenance measures for low-slope or flat roof include recoating. This should be done according to the recommendations of qualified roofing repair professionals. Additionally, it’s important to make sure that there’s a proper working drainage system and that any water collection or accumulation is minimal enough to evaporate within a day of the rains.

Repairing a flat roof

You know you've got a leak when damp patches start appearing on the ceiling or walls. Your local Builders Warehouse will be able to offer advice on the best repair material for your particular roof. The best time to tackle any roof repairs is during the dry season, but before it gets too hot. Warm, dry weather makes it easier to spread roofing compounds and attend to any roof repairs. Grab yourself a stepladder and a sweeping brush so that you can clean the roof area to determine any damage on the roof or flashing around the edges.

Flashing is the seal around the perimeter of a roof and is fastened or adhered to the surrounding brickwork to create a seal around edges. Flashing that has come away from the wall is a common cause of leaks and is easily repaired by replacing the damaged section and applying a thick layer of rubberised roofing compound to stick down the flashing.


Roofing felt with a bitumen overlay is an affordable option for flat roofing, but does require regular maintenance. This type of roofing is best left to a specialist roofing contractor as the layers or felt and bitumen must be bonded to each other and finished off with mineral chips to strengthen the roofing. For general maintenance a renewing compound should be applied every 4 to 5 years.



In new home construction, a flat concrete roof is aesthetically pleasing from a design point of view, but requires a great deal of maintenance. Foundation settlement, ground movement and other factors can lead to shifting and cracking. To fix a concrete roof that is leaking is a fairly easy process - even for the do it yourselfer.

The first thing you should do is to power wash the entire surface area of the roof, which will remove most of the loose material. After preparing the surface you will need to prime the roof with suitable primer or bonding liquid. This liquid will flow into the cracks and crevices of the concrete rooftop and bond to the concrete.

DIY Tip:
Always run a test patch first in an inconspicuous area, to ensure that proper adhesion and drying occurs and the product works to your satisfaction.

Use seam tape or membrane over all cracks and then apply acrylic sealer or bitumen coating product. Where acrylic sealer is applied note that repeat application is required every 3 to 4 years, or when necessary.