ᐅ Patio without slope – According to which standard or regulation?
Created on: 26 Aug 2025 18:45
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HausbauFrage
Hello!
Our outdoor area, including the terrace, was recently installed by a landscaper. Since our house is a timber frame construction, a base channel was installed between the house and the ground-level terrace. It is an Aco Profi Line with a width of 25cm (10 inches) and a height of 30cm (12 inches), which drains through the side slots into the gravel bed. The terrace consists of concrete slabs laid on a layer of gravel. The joints were filled with joint mortar, so no significant drainage through the terrace joints is expected.
Now we have noticed that the terrace has no slope...
What could be the worst-case scenario, and are there any measures that could be taken without completely relaying the terrace?
I see the risk that during heavy rain, a large portion of the water will flow toward the house, and the base channel might not drain the water fast enough through the drainage slots.
Also, I have read about algae growth. Does this actually occur in practice?
Which DIN standard or other regulation specifically states that a slope away from the house is part of the recognized rules of technology?
Our outdoor area, including the terrace, was recently installed by a landscaper. Since our house is a timber frame construction, a base channel was installed between the house and the ground-level terrace. It is an Aco Profi Line with a width of 25cm (10 inches) and a height of 30cm (12 inches), which drains through the side slots into the gravel bed. The terrace consists of concrete slabs laid on a layer of gravel. The joints were filled with joint mortar, so no significant drainage through the terrace joints is expected.
Now we have noticed that the terrace has no slope...
What could be the worst-case scenario, and are there any measures that could be taken without completely relaying the terrace?
I see the risk that during heavy rain, a large portion of the water will flow toward the house, and the base channel might not drain the water fast enough through the drainage slots.
Also, I have read about algae growth. Does this actually occur in practice?
Which DIN standard or other regulation specifically states that a slope away from the house is part of the recognized rules of technology?
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ajokr202527 Aug 2025 19:01There is a ZDB information sheet on terrace coverings, but unfortunately it is only available for a fee. Apparently, the craftsman is not interested in it.
A slope of 1.5% should definitely be applied.
A slope of 1.5% should definitely be applied.
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MachsSelbst27 Aug 2025 20:43Enlighten us, where is the instruction?
A slope must be executed continuously, not in steps, waves, or randomly distributed...
You’re not seriously suggesting that something like this has to be measured with a laser?
A slope must be executed continuously, not in steps, waves, or randomly distributed...
You’re not seriously suggesting that something like this has to be measured with a laser?
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HausbauFrage28 Aug 2025 18:15Thank you all for the feedback.
I first checked it with a spirit level and then measured the slope as accurately as possible. Depending on the measurement point, it is about 0.25% sloping away from the house.
I first checked it with a spirit level and then measured the slope as accurately as possible. Depending on the measurement point, it is about 0.25% sloping away from the house.
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MachsSelbst28 Aug 2025 22:21Yes, that’s unfortunate. Don’t let it get to you here; it’s really unpredictable which way the pendulum will swing. Sometimes the tradespeople are directly blamed, sometimes the client—that is, you—is unfairly accused of not having measured correctly or is doubted in their ability to judge such matters at all.
With some specialists here, I actually doubt they have ever even held a spirit level themselves or created a slope or leveled something... because in practice, every tradesperson first checks their work with a spirit level. Whether it’s the carpenter installing a door frame, the mason checking their wall, or the landscaper setting block steps, edging stones, or a terrace. And if the bubble is within the inner markings, that counts as level and has nothing to do with slope.
With some specialists here, I actually doubt they have ever even held a spirit level themselves or created a slope or leveled something... because in practice, every tradesperson first checks their work with a spirit level. Whether it’s the carpenter installing a door frame, the mason checking their wall, or the landscaper setting block steps, edging stones, or a terrace. And if the bubble is within the inner markings, that counts as level and has nothing to do with slope.
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wiltshire28 Aug 2025 22:28HausbauFrage schrieb:
Depending on the measuring point, it is about 0.25% slope away from the house. That is too little.
What kind of transition is there from the terrace to the house wall? Is there contact with the timber structure, a slab foundation, or concrete?
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