ᐅ Installing dimple membrane retroactively?

Hello everyone,

we are currently having the facade of our house replastered. For this, we removed the first row of patio slabs in front of the facade so the plasterer can work easily down to the bottom.

Now the idea has come up that since the facade is already being worked on, we might as well install a dimpled membrane – mainly to protect the plaster from rising moisture.

Here are the conditions:
The house was built in 1975. The basement is made of concrete blocks, partly sandstone blocks (from a previous building on the site). The upper floors, which form the main part of the facade, are built with aerated concrete blocks (Ytong). So far, we haven’t had any moisture issues in the basement. On the facade, a sort of waterline is slightly visible near the base, but only if you know where to look.

Our question now is whether installing a dimpled membrane makes sense in this situation or if it might actually be counterproductive. And if it is advisable, how far down should the basement wall be exposed for this to have any real effect?

Thanks in advance!

Try searching for "base guideline" or "base primer," you will find helpful information.

A dimpled membrane is not a waterproofing layer against moisture, but rather protection against mechanical damage. The waterproofing must be applied on the wall (or behind the insulation, but it seems there is none).

A dimpled membrane is rarely counterproductive, but it is not really essential either. And if used, the membrane should extend down to the footing.

Hello

Dimpled membrane does not provide any benefit on its own.
If you want to do it properly, you need to go down to the foundations.
Expose everything, clean the walls thoroughly, apply a 5mm (0.2 inch) thick layer of bituminous coating or mastic, then install Styrofoam or extruded polystyrene (XPS). On top of that, apply the dimpled membrane.

Steven

Steven schrieb:
Hello

Dimpled membrane doesn’t help initially.
If you want to do it properly, you need to go down to the foundations.
Expose everything, clean the walls thoroughly, apply a 5mm (0.2 inch) thick layer of thick-bitumen coating or bituminous mastic, then add Styrofoam or extruded polystyrene (XPS). And on top of that, the dimpled membrane.

Steven

You might want to ask an expert what the dimpled membrane does to the Styrofoam/XPS under lateral pressure! That would be a defect that a general contractor would need to fix immediately.

Also, XPS does not require separate moisture protection, neither bitumen nor dimpled membrane.

Always just hearsay...

Zaba12 schrieb:
You might want to ask an expert about what the dimple membrane does to the polystyrene/foam board under lateral pressure! Always just hearsay...

Hello Zaba12

What exactly does the dimple membrane do to the polystyrene/foam board? I’m really interested. Entire houses are built on top of it, so the material must be quite pressure-resistant. So, what exactly happens with the dimple membrane in this context?
Having built three houses myself and done a lot of the work personally, I’d be interested in your knowledge.

Steven

Steven schrieb:
Hello Zaba12

What exactly does the dimpled membrane do to the polystyrene/rigid foam board? I’m really interested. Entire houses are built on top of it, so the material must be quite pressure-resistant. So, what exactly does the dimpled membrane do in this case?
After building three houses and doing a lot of the work myself, I’m curious about your knowledge.

Steven

The dimples can tear the insulation when backfilling and simultaneously shifting the dimpled membrane. Feel free to ask an expert or building inspector; they will give you the same answer, Steven.

Just because many DIYers do it this way doesn’t mean it’s correct. Some smart ones even do this on a waterproofed basement wall :-p, probably for peace of mind.