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What are common flat roofing problems, and how do you fix them?

Most flat roofing problems can be solved proactively – just make sure you use a professional and experienced roofer to install your roof, use the most suitable materials for your building, and ensure regular inspection and maintenance is undertaken to prevent any small issues becoming much bigger problems.

 

Flat Roofing Problem #1: Ponding waterwater-damage

Compared to pitched roofs, flat roofs do not drain very well, and as such they commonly develop ponding water – defined as water that stands in a puddle on a roof for 48 hours or more. The issue only develops if the water remains there for a period of time, because it can begin to create stress on the membrane and begin wearing it down. Furthermore, the ponding water can result in leaking due to the stress on the membrane becoming too much, and allow moisture into the roof structure.

The solution to ponding water

The best way to combat ponding water is to be proactive and keep the roof well maintained. It’s important to ensure your gutters and drains are maintained, and any blockages cleared as quickly as possible to prevent ponding water. Additionally, ensuring the person installing your roof is experienced and professional can help to remove any potential for ponding water.

Placing patches over a small ponding area can be a simple and quick fix to prevent further build up of water. Dry the water out using rags or towels and leave to dry. Cut a 12 inch circle of rolled asphalt, spread roofing cement to the bottom of the patch, and place onto ponding area. Then cut more circles out, each time increasing the circle size by 4 inches, until you have 10 circles. Each time place the patch on top of the previous one, using roofing cement. When complete, apply a thick rubber or elastomeric coating to seal, and once dry test it by adding water on top of it.

If there are numerous pools of water, or it is a large area of pooling, it may be the case that the whole roof membrane needs to be replaced.

 

Flat Roofing Problem #2: Blistering

Blistering occurs on your flat roof when small pockets of air or moisture get trapped beneath the membrane or in between layers of membrane. This worsens when the sun warms the roof up, which causes the pockets or air or moisture to expand, stretching the membrane.

The solution to blistering

Generally, as long as they stay intact you don’t need to worry too much about the blistering. Keep a close eye on them, and if they pop you can then replace or repair them. To repair blisters, cut away the blistered material up to the point that it is attached tightly to the roof still. Then reapply new membrane material, extending it at least 6 inches over the edge of the blister to prevent leakage.

It’s important to keep your roof well maintained and cleaned regularly – any build up of moss or algae can contribute to trapped moisture or water that may cause blistering.

 

cracked-roof

Flat Roofing Problem #3: Alligatoring

Alligatoring is the term used to describe the cracking of a coating or surfacing bitumen on a flat roof, which causes a pattern similar to the hide of an alligator.  This can be caused due to water, debris or long term exposure to the sun. The cracking will eventually split and develop further if left unrepaired, meaning that water can get into the roofing and cause leaking, moisture and more damage.

The solution to alligatoring

To fix alligatoring, one solution is to apply a new coating to the roof. First, clean the roof thoroughly, removing all dust, dirt and anything else that is loose. Then apply a primer, and once the primer has dried apply the coating.

Flat Roofing Problem #4: Buckle in membrane

Houses shift slightly and settle over time, and this means that so does the roofing membrane, which is between the house and the roof. In most cases, the membrane is a single sheet, which means that the movement may cause it to buckle. Unfortunately, there isn’t a really easy fix to this, and you’ll need to get a professional out to look at it and find a solution.

 

Flat Roofing Problem #5: Thermal movement

Temperature changes can cause the roofing material to expand and contract, which is relatively normal. However, you must keep an eye on your roof for evidence of this, as continual expansion and contraction can weaken the roof and potentially cause leaks. This thermal movement can also occur on the flashing, resulting in it pulling away from the edges of your roof over time – this leaves room for leakage and moisture entry into your roof.

The solution to thermal movement

Ensure you use good quality flashing and roofing materials, and that they are installed properly, with regular maintenance. If you notice some flashing pulling away from the edges of the roof or house, its best to replace the flashing.

 

Flat roofing products including EPDM, liquid rubber membranes and fibreglass roofing products are all available here. Contact our experts on 01752 692 760 for more information and advice on tackling these flat roofing issues.

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