In terms of use of materials, a flat roof is the most efficient use of resources, as it allows for the most indoor space for the least materials, with a versatility not typically found with slanted roofs.

When constructed by a specialist using modern waterproofing materials and with the appropriate level of runoff, a flat roof can serve as an ideal extra space, particularly for commercial buildings, which is why there has been a prevailing trend towards flat roofs in an industrial context.

There are also plenty of stylish residential homes that use a flat roof as part of their design, but interestingly the UK was surprisingly late to adopt what had been used in Ancient Egypt and as part of historical Persian and Arabian architectural styles.

The initial reason for this was a matter of practicality before it became a matter of tradition and aesthetics.

In warmer climates such as those found in Egypt, it was much easier to build houses out of stone or brickwork than it was to find enough timber to construct a wooden shelter.

In these climates, without a lot of rain, a flat roof made out of materials potentially vulnerable to water would be perfectly fine as they are perfectly suited to keep out the sun’s heat, provide shelter and shade during the day, and would not be vulnerable to potential damage.

By contrast, somewhere like the UK has a lot of rainfall and the potential risk of freezing, which means that these traditional masonry buildings would have been vulnerable to water seeping in, expanding through the freeze-thaw cycle and creating big holes in the roof.

This is not a problem today as far more advanced materials are used to construct the roof, waterproof the structural materials, as well as avoiding pooling and adding extra weight to the top of the building.