rschraml
2025-07-27 13:45:26
- #1
Greetings,
I have already read many posts on the topic in the forum, and there are different opinions depending on the situation. Therefore, I would like to ask for your opinions regarding our basement project.
We have started the basement renovation. In the past, the floor (brown clay) between the strip foundations was about 10cm of concrete on some gravel. We never had water in the basement, but there were one or two spots where you could see damp base areas during heavy rain. Before starting the renovation, I made a pit in the basement, where water accumulated during heavy rain, but it never overflowed.
Our house has a newer extension (also with strip foundation), which is 70cm lower, and there we repeatedly had problems during heavy rain. The drainage there could not transport the water away, and then the water was pushed inside there. But not in our basement, which is higher.
We have now exposed our basement down to the underside of the strip foundations, and with the current amount of rain, water is being pushed under the strip foundations into the basement. It is currently only kept dry by pumping. The drainage in the lower part of the house currently has no problems, and it seems to me that less water arrives there.
Execution question:
The next step is the installation of the floor slab (20-25cm waterproof concrete with reinforcement, followed by sealing the edge areas with resin). The builder suggests installing drainage under the floor slab with a soakaway shaft and pump so that we can pump the water out. This means laying drainage along the outer wall but on the inside under the floor slab where water is being pushed in, and then covering everything with gravel, approximately a 5cm blinding layer before the concrete is poured.
I keep wondering whether this makes sense? With the drainage and blinding layer, I would have a capillary layer exactly where the water is being pushed in.
Would it possibly be better to concrete cleanly down to the underside of the foundations, without a blinding layer and drainage, so that the water is still "blocked" or pushed away as much as possible?
Doing something from the outside is almost impossible.
What do you think, or what are your experiences? Attached are a few pictures.
I have already read many posts on the topic in the forum, and there are different opinions depending on the situation. Therefore, I would like to ask for your opinions regarding our basement project.
We have started the basement renovation. In the past, the floor (brown clay) between the strip foundations was about 10cm of concrete on some gravel. We never had water in the basement, but there were one or two spots where you could see damp base areas during heavy rain. Before starting the renovation, I made a pit in the basement, where water accumulated during heavy rain, but it never overflowed.
Our house has a newer extension (also with strip foundation), which is 70cm lower, and there we repeatedly had problems during heavy rain. The drainage there could not transport the water away, and then the water was pushed inside there. But not in our basement, which is higher.
We have now exposed our basement down to the underside of the strip foundations, and with the current amount of rain, water is being pushed under the strip foundations into the basement. It is currently only kept dry by pumping. The drainage in the lower part of the house currently has no problems, and it seems to me that less water arrives there.
Execution question:
The next step is the installation of the floor slab (20-25cm waterproof concrete with reinforcement, followed by sealing the edge areas with resin). The builder suggests installing drainage under the floor slab with a soakaway shaft and pump so that we can pump the water out. This means laying drainage along the outer wall but on the inside under the floor slab where water is being pushed in, and then covering everything with gravel, approximately a 5cm blinding layer before the concrete is poured.
I keep wondering whether this makes sense? With the drainage and blinding layer, I would have a capillary layer exactly where the water is being pushed in.
Would it possibly be better to concrete cleanly down to the underside of the foundations, without a blinding layer and drainage, so that the water is still "blocked" or pushed away as much as possible?
Doing something from the outside is almost impossible.
What do you think, or what are your experiences? Attached are a few pictures.