A roof that leaks and a top floor that overheats usually have the same fix: rebuild the roof as one system. In a combo roof, a waterproof membrane goes on the slab, insulation boards go over it, and a screed laid to falls and a top finish protect both. Done in that order, the membrane keeps water out and the insulation keeps the sun's heat off the rooms below.
Why the top floor gets so hot
In summer the roof is the surface that takes the most direct sun all day. A bare concrete slab with only a thin screed and tiles soaks up that heat and releases it into the rooms below well into the night. Many older villas were built with little or no roof insulation, which is why the top-floor bedrooms are often the hottest rooms in the house, with the AC running hardest.
Why leaks and heat go together
The same roofs often leak too. Heat makes the slab expand and contract every day, which cracks screed and tiles and fatigues old membranes and sealants. Once water gets into the screed, it also makes any insulation in the roof less effective. So fixing one problem without the other often means opening the roof twice.
What a combo roof is
A combo roof is a full build-up installed as one job. From the slab up:
- Primer and waterproof membrane, usually torch-on bitumen sheet, turned up at every parapet, plinth and drain.
- Thermal insulation boards laid over the membrane.
- A separation layer so the screed does not bond to the boards.
- Screed laid to falls, so water runs to the drains instead of ponding.
- A top finish, such as tiles or a protective screed finish.
The roof is flood-tested before the finish is completed, so any leak is found while it is still easy to fix. For new buildings, Dubai's green building rules (Al Sa'fat) also set insulation requirements, which a combo roof is designed to meet.
When it is worth it
- The roof leaks and the top floor is hot: rebuilding as a combo roof fixes both at once.
- You are retiling the roof anyway: adding the insulation and a new membrane at the same time costs far less than doing it later.
- The roof only leaks at one detail and the top floor is fine: a targeted repair or a membrane on its own may be enough.
What to check before you decide
- Levels: the build-up adds thickness, so door thresholds, parapet heights and drain levels have to allow it.
- What is already there: a test opening shows whether the old layers can stay or must come off.
- Drainage: the new screed must fall to working drains.
We survey the roof, open a test area and give one fixed quote for the full combo roof system. Send photos of the roof and tell us which rooms get hottest.