ᐅ Bitumen waterproofing membrane on the concrete slab

Hello,

can someone explain to me why this is sometimes done and sometimes not?

The bituminous membrane serves as a barrier against rising damp. It is currently the standard technology. Some companies argue that a capillary-breaking layer and a plastic sheet beneath the slab are sufficient and can replace the membrane. I would never do without it. The cost is negligible within the overall construction budget.

Okay, thanks, that makes sense.

I have often read that this is not done because the concrete needs to breathe upwards?

Smarti99 schrieb:

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Now, I have often read that this is not done because the concrete needs to breathe upwards?

Is the concrete supposed to breathe into the screed? Contractors often say whatever suits them to present their way of doing things as the right one.

Smarti99 schrieb:

Does concrete need to breathe upwards?

Absolutely, but only if you embed lungs in it; otherwise, not really.

Vicky Pedia schrieb:

There are companies that argue a capillary-breaking layer and a membrane under the foundation slab are sufficient, saving the need for a waterproofing sheet.

However, they seem to forget about moisture penetrating from the sides.
This also weakens the argument for waterproof concrete, as the material thickness on the sides is not adequate.
The slab must be fully sealed, extended down over window and door openings to prevent any moisture infiltration behind the sealing.
That’s also important for the window connection, which we recently discussed.

Smarti99 schrieb:

I have often read that this is not done because the concrete slab needs to breathe upwards?

No need to worry about ‘concrete bronchitis’.
Sealing the slab is a step that comes before the windows. By that time, the concrete has already been curing for a while.