ᐅ Flat Roof Waterproofing for Terrace / Floor Covering

Created on: 21 Apr 2020 14:12
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Kira1980
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Kira1980
21 Apr 2020 14:12
Hello dear forum,
I have been following along for a while and today decided to register because I’m not really sure how to proceed.
We are currently building a new house and are working on the terrace. We want to build it over our garage, which is planned to have a flat roof. The interior build-up height is 14cm (5.5 inches), and the balcony door is threshold-free, so the exterior build-up height is also 14cm (5.5 inches).
At the moment, the concrete slab has no slope. The plan was actually to have a sloped screed extending over 7m (23 feet).
The architect recommends a 0-degree roof, which makes us somewhat uneasy, so we are now considering the sloped screed again.
A 40mm (1.6 inches) XPS insulation board is planned to be used, with a fleece-backed membrane installed on top, which brings the build-up to 43mm (1.7 inches) and is already in place.
Everything else is still open. Any ideas on this?
We are quite flexible regarding the surface covering.
rick201821 Apr 2020 18:05
Install tapered insulation and then raise the terrace. It’s best to collect the water in a cistern. Normally, you would plan such details before starting. However, this is more of a “simple exercise.”
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guckuck2
21 Apr 2020 18:13
Sloped screed with insulation or sloped insulation, both are possible and common.

But I still don’t quite understand your heights?
If the door is supposed to be threshold-free and a slope of 2° over 7m (23 feet) is necessary, assuming the slope goes away from the door, then you already have a height difference of 14cm (5.5 inches) just due to the slope. This leaves no room for flooring. Therefore, probably the suggestion of a flat roof with 0° slope, which is technically definitely feasible but will cause additional costs.
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Kira1980
22 Apr 2020 08:34
Thank you for the responses. Unfortunately, the slope insulation with a 2-degree incline is no longer an option.
Do you have any ideas for a covering? We have already considered a 1-degree slope for the screed, so that we would have at least some incline, and then apply a relatively thin layer on top. The covering would then have 7cm (2.8 inches) - 4.3cm (1.7 inches) = 2.7cm (1.1 inches) left.
The cistern is a good idea, thank you!
rick201822 Apr 2020 08:52
Raising the surface. Water drains through the covering, and the slope underneath is evened out so that the surface is level.
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Kira1980
22 Apr 2020 08:58
Is a 1% slope sufficient, and what type of surface would you recommend for a thickness of 2.7cm (1 inch)?