ᐅ Flat Roof Waterproofing for Terrace / Floor Covering

Created on: 21 Apr 2020 14:12
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Kira1980
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.
G
guckuck2
22 Apr 2020 11:28
Kira1980 schrieb:

Thank you very much for the replies. Unfortunately, the sloped insulation with a 2-degree slope is no longer an option.
Do you have any ideas for a surface covering? We have already considered a 1-degree slope in the screed, so that we would at least have some slope and then apply a relatively thin build-up 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, thanks!


However, the sloped insulation would be preferable in terms of build-up thickness compared to doing it with the screed.
Or do you actually not need any insulation? Then the screed is naturally preferable, at least from a cost perspective.

And to repeat once more, if you really have 7m (23 feet) of slope from the door at 2%, there is absolutely no space left for a floor covering.
You could also create a counter-slope so that water is directed to a drain in the center of the roof (which would have an impact on the room below), or to a channel that leads to a drainage point.

A 0% slope is sufficient, as your architect already says. However, the roof must be executed accordingly.
You shouldn’t negotiate this further; no one will make this decision for you. It is your responsibility as the building owner.
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Kira1980
22 Apr 2020 16:21
Yes, you’re probably right. I’m just looking for alternatives and wondering how other builders have solved a similar problem.
T
Tassimat
22 Apr 2020 16:25
What if you skip the threshold-free balcony door?
Besides rain, there is also snow.
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Kira1980
23 Apr 2020 10:33
Honestly, rather reluctantly, but it will probably come down to that.