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Pooled water on flat roof

High-level inspection finds “swimming pool” where flat roof used to be

It might have been wet recently, but flat roofs should not look like this.

We’ve had a very rainy autumn this year, with areas such as Sheffield reporting that 2019 has been the wettest autumn on record. However, a flat roof should be able to drain water effectively. A slight slope, known as a ‘fall’, directs rain towards guttering. As long as this is not blocked, it will carry the water away.

As our surveyor found, that was not happening with this roof. As part of the building survey, a 10m telescopic inspection camera was used to get a close look at the roof’s condition. This allowed the surveyor to diagnose the problem and advise the client on the necessary repairs.

In the case in the photo, the falls needed altering to increase the slope of the roof. The pooled rainwater had also damaged the felt, so this needed to be replaced too.

If an extensive roof repair is not carried out, the water will damage the roof structure below the felt, and the owners will be at risk of leaks.

Problems with flat roofs can occur if the guttering is inadequate, or if it is blocked by leaves and other debris. In addition, dips and dents in the roof can encourage water to collect, or, as in this case, insufficient pitching stops water draining away.

If ignored, standing water can damage roof material, weigh it down so that it sags further, and allow the growth of moss and other plants. Ultimately, this can lead to water ingress and even collapse of the roof itself.