This article discusses flat roofs being beneficial in places with very little or without rain. When the rain comes, these houses that are using flat roofs should have used suitable waterproof materials for their roof as the main problem will be water accumulation and possible leakage.
As stated here, homeadvisor.com had listed down popular flat roofing systems – its benefits and drawbacks.
This means roofs that are built by adding more layers and is also known as “tar and gravel” roofing since it is finished off with a final coating of gravel, crushed rock, or other mineral substances to minimize sun damage.
Another popular Built-Up roofing style is a modified bitumen roof, which is made of fiberglass-based asphalt sheeting applied in layers with mopped-on bitumen layers between each. Although this is more likely to be used by commercial buildings, houses with flat roofs can also use this.
This is the most common, reliable, popular, and practical flat roof solution in the market. Two types of Single-Ply roofs are Thermoset membranes, which are manufactured from rubber polymers and Thermoplastic membranes, which are made from plastic.
Sprayed Polyurethane Foam
This is a relatively new product in the market. Since the foam is flexible and lightweight, there is no need to remove the previous roof for those who are doing re-roofing. This is also beneficial for those uneven roofs. As mentioned in the article, the downside of this method is the track record to prove if this is worth a try.
Hire an Experienced Roofer
Since flat roofing is never a D.I.Y. project, you will need to hire an experienced roofer to make the necessary changes to your roof and ensure everything is done correctly.