ᐅ Foundation/Base for WPC Decking

Created on: 8 Apr 2016 11:30
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baudu
Hello dear forum members,

The boss asked me to build a WPC deck. Currently, there is still grass growing there. The area measures 4 x 5 m (13 x 16 ft) and starts from the patio door. I am only concerned with the foundation.

This is what I have planned:
1. Dig to a depth of about 30 cm (12 inches).
2. Lay a geotextile membrane.
3. Spread a 20 cm (8 inch) layer of crushed stone, compacted with a plate compactor, with a 4% slope.
4. Add a 10 cm (4 inch) bedding layer of fine crushed stone, compacted again, with a 2% slope.

On this, I want to place individual rows of concrete edging stones, on which I can install the substructure.
I also plan to edge the whole area to prevent lateral slipping.

So far, so good. This also complies with the manufacturer’s specifications. Then a representative from a landscaping company came to make me an offer and said that he would never do it without concrete and reinforcing mesh and that he could not guarantee the work if done the way I am planning.

As I said, I wanted to do it myself anyway, but now I am a bit unsure.

Please share your opinions and knowledge on this subject.

Thank you in advance and have a nice weekend!
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Sebastian79
12 Apr 2016 18:05
The technical regulation requiring a slope still applies – I didn’t just make that up...
Neige12 Apr 2016 18:48
Sebastian, I am not aware of any regulation that strictly requires a slope for terraces. There are only guidelines provided by manufacturers to exclude liability. There are indeed DIN standards and recognized technical rules that specify what must be considered in construction.
Our architects or surveyors can certainly provide more precise information on this. I am quite sure that there is no mandatory regulation regarding the slope.
Please correct me if I am wrong.
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Sebastian79
12 Apr 2016 18:53
I meant precisely the accepted standards – what else could there be? The slope rule?
Neige12 Apr 2016 19:12
Interesting discussion. In my view, the "recognized rule" could also mean that measures must be taken to prevent water from entering the house, even if the terrace has no slope. As far as I know, this must be communicated among all parties involved in the construction. Or is what I am saying nonsense?
I am not familiar with the relevant standards and regulations in this regard.

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Sebastian79
12 Apr 2016 19:15
In theory, you need a channel and actually a 15cm (6 inches) step for that.

And I BELIEVE that the DIN standard does not differentiate between types of floor coverings but always requires a slope away from the house – which should generally be a basic rule. However, with a wooden terrace, I wouldn’t follow that rule too strictly.

But I wouldn’t dismiss it as nonsense either...
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Bauexperte
12 Apr 2016 21:02
The DIN standard does not require anything at all; it even allows for zero slope.


Bauexperte