ᐅ Pouring a Concrete Patio – Connection and Thermal Separation from the Building

Hello everyone,

we are currently considering whether to pour a separate concrete slab for the terrace as part of our house construction.

How exactly is the separation / waterproofing done in relation to the main building?

The building’s concrete slab ends with the perimeter insulation and is sealed with a waterproofing slurry.

Should the terrace slab now be poured directly against the building’s slab, simply making the perimeter insulation thicker? Or is there actually an air gap between the two slabs?

I will still discuss this with the structural builder, but I want to inform myself about the topic in advance.

In terms of height, I am planning to stay about 10cm (4 inches) below the finished floor level, to leave enough options for the terrace surface.

The slab will of course be poured with a slope, and the foundation will be protected against frost.

Thank you very much.

How thick is the current perimeter insulation on the house? I don’t see any issue with it as long as the two slabs don’t touch each other. I would place a separation strip between the terrace slab and the perimeter insulation of the house, but that would be more for my own peace of mind. I don’t think extensive measures are necessary here. The slab of our garage was even poured directly up to the house’s slab/bricks without any separation strip, waterproofing, or anything else. Afterwards, I thought a separation strip would have been nice for reducing structural-borne noise. We’ll see if we end up hearing the garage door opening and closing inside the house.

But again, I would add a separation strip so that the terrace slab is completely independent from the house, both physically and thermally.

*Edit:
You don’t need to waterproof the terrace slab itself; just use the appropriate concrete and make sure the base is frost-resistant.

The perimeter insulation should be 10cm (4 inches) thick.
By separation strips, do you mean, for example, additional perimeter insulation?

I also think the topic of drainage channels in front of the floor-to-ceiling windows plays a role here:

- Drainage of the channels via surface drainage: In this case, the concrete slab would necessarily have to be brought right up to the house?
- Drainage of the channels by connecting to the rainwater pipe: Here, there would necessarily have to be a gap between the concrete slab and the house, otherwise I wouldn’t be able to connect the channels to the pipe.

What are the experiences here? Drainage channels with surface drainage are sometimes extremely expensive. Which option is usually used here?
The second alternative would also have the advantage that, at least in those spots, you would have access to the rainwater pipe again.

Jackil26 schrieb:

The perimeter insulation should be 10cm (4 inches) thick.
By separating strip, do you mean another layer of perimeter insulation?

I also think the topic of drainage channels in front of the floor-to-ceiling windows plays a role here:

- Drainage of the channels via surface drainage: In this case, the concrete slab would necessarily have to be connected to the house, right?
- Drainage of the channels via connection to the rainwater pipe: Here, there would necessarily have to be a gap between the concrete slab and the house; otherwise, I wouldn’t be able to connect the channels to the pipe.

What are the experiences here? Some channels with surface drainage are really extremely expensive. Which option is usually used here?
The second alternative also has the advantage that at least in these places you still have access to the rainwater pipe.

A separating strip is basically the same thing that the screed installer lays along the wall. It is mainly done to prevent impact sound from being transmitted to the wall.

We also chose facade drainage with a connection to the soakaway pit. As I mentioned in another thread, this was for protective reasons and partly to keep regular rainwater away from the basement as much as possible, since we understandably only have limited trust in the waterproof concrete structure (WU construction) in our specific case.

Yes, there are channels that simply drain into the surrounding areas and basically serve as a replacement for the gravel strip along the facade, and there are channels (Aco, Anrin, etc.) that are connected to a KG pipe and drain into the sewer, soakaway pit, cistern, infiltration system, etc.

We laid all the drainage pipes in the ground during the basement construction. That would also be conceivable for you. The KG 2000 pipes last at least as long as your terrace’s concrete slab, so I wouldn’t worry about that. Install them so that only the channel needs to be installed at the end. By the way, these channels are also installed in concrete and not just buried in sand. If you want to leave a gap, simply add another 1-1.5cm (0.4-0.6 inches) to the width of the channel body for the separating strip, and you’ll be on the safe side. Depending on the model, the channels can even be connected on the end face, which makes retrofitting the connection really easy.