ᐅ Concrete slab and house protected against moisture with dimpled membrane? Any experiences?
Created on: 21 Jun 2025 23:04
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Bauherrin123
Hello dear homeowners,
Who has experience and can help me? I have been living in the house for 2 years, and now it’s time to work on the exterior landscaping. We have now installed dimpled membrane (drainage membrane) for the terraces, but it already seemed wrong to me. I have since read up on it and am still unsure. Did my construction company deliver a house without properly waterproofing the exterior or what?
The house has no basement. A neighbor said the company applied bitumen and then a slurry coat, and that would be sufficient. Additionally, we are installing the dimpled membrane, which should be more than enough.
Now I don’t know if the dimpled membrane was installed correctly, if the company really applied bitumen, and if everything we're doing is enough — or if we should call a specialist? Attached is a photo; I am totally confused. What do I need to do to protect my house from moisture and damage for the next 10 years? I don’t want to forget anything, as everyone says something different: One road construction worker offers to do it for 150 euros, saying he will remove the gravel, apply the slurry coat, and install the dimpled membrane with the dimples facing the wall. Another person says it would cost 5,000 euros and that there needs to be insulation, then a layer – I don’t know what exactly – then styrofoam, and then the dimpled membrane with drainage.
I am confused.
Who has experience and can help me? I have been living in the house for 2 years, and now it’s time to work on the exterior landscaping. We have now installed dimpled membrane (drainage membrane) for the terraces, but it already seemed wrong to me. I have since read up on it and am still unsure. Did my construction company deliver a house without properly waterproofing the exterior or what?
The house has no basement. A neighbor said the company applied bitumen and then a slurry coat, and that would be sufficient. Additionally, we are installing the dimpled membrane, which should be more than enough.
Now I don’t know if the dimpled membrane was installed correctly, if the company really applied bitumen, and if everything we're doing is enough — or if we should call a specialist? Attached is a photo; I am totally confused. What do I need to do to protect my house from moisture and damage for the next 10 years? I don’t want to forget anything, as everyone says something different: One road construction worker offers to do it for 150 euros, saying he will remove the gravel, apply the slurry coat, and install the dimpled membrane with the dimples facing the wall. Another person says it would cost 5,000 euros and that there needs to be insulation, then a layer – I don’t know what exactly – then styrofoam, and then the dimpled membrane with drainage.
I am confused.
N
nordanney23 Jun 2025 10:57derdietmar schrieb:
The appropriate membrane for this purpose is the mentioned Delta Terraxx with fleece, with the fleece facing outward. Due to the flat and even contact of the smooth side against the façade A brief correction. That is a studded membrane, whose intended use is in basement construction, flat roofs, green roofs, vehicle traffic areas, etc. Furthermore, and this is the strength of the product, it is used as a drainage system in combination with a drainage pipe (DIN Schlagmichtot) or as a water-conducting layer in various horizontal applications. That is why it comes with fleece.
For pure mechanical protection, it is the wrong product (although it technically works, it is like a gold-plated faucet—nice but unnecessary).
derdietmar schrieb:
If the black membrane is mistakenly used for building protection on waterproofed façades, the studs can press into the (soft) waterproofing or external thermal insulation composite system (ETICS). Due to ground settlement movements, the waterproofing or ETICS is pulled downward and torn off. Moisture then penetrates the resulting cracks. Fortunately, in this case, only a few centimeters (about an inch) are involved at the foundation slab, and there is no ETICS present.
But Grundstück., your statements are correct in general, just not applicable to the specific case of the original poster.
D
derdietmar23 Jun 2025 11:08Hello,
the Delta Terraxx is, of course, just one example; there are alternative products as well. I have had good experiences with this product—the seams can even be glued on the prefabricated adhesive tabs, and the fleece is hardly damaged. You also get additional drainage at the façade.
In the case above, there is no full-surface external thermal insulation composite system (ETICS / EIFS), but a flexible waterproofing on a soft substrate in the base area (slurry over bitumen on EPS). This can theoretically also be damaged, as shown in the example photos. Therefore, my clear recommendation here is also for a two- or three-layer membrane with appropriate pressure release (many studs, thick plastic). The costs are higher, but for functional safety, a few hundred euros should not be the deciding factor. I would not use the black membrane from the first photos of the thread.
Sources: Google search (Erdell and DEGA garden landscaping)
Kind regards
the Delta Terraxx is, of course, just one example; there are alternative products as well. I have had good experiences with this product—the seams can even be glued on the prefabricated adhesive tabs, and the fleece is hardly damaged. You also get additional drainage at the façade.
In the case above, there is no full-surface external thermal insulation composite system (ETICS / EIFS), but a flexible waterproofing on a soft substrate in the base area (slurry over bitumen on EPS). This can theoretically also be damaged, as shown in the example photos. Therefore, my clear recommendation here is also for a two- or three-layer membrane with appropriate pressure release (many studs, thick plastic). The costs are higher, but for functional safety, a few hundred euros should not be the deciding factor. I would not use the black membrane from the first photos of the thread.
Sources: Google search (Erdell and DEGA garden landscaping)
Kind regards
N
nordanney23 Jun 2025 11:30derdietmar schrieb:
In the above case, there is no full-surface ETICS, but a flexible sealing on a soft substrate in the base area (slurry on bitumen on EPS) I agree that the substrate is soft. But pressure-resistant XPS must be used down there. EPS has no place in that area (the green color also clearly indicates XPS).
And yes, membranes with a slip layer and fleece are better. But – and here the original poster provides no details – the water load on the house must be considered. Is there drainage or not, any pressing or standing water, etc.
Also, the “concern” about the bitumen coating as a completely wrong product (bitumen coating and slurry are not wrong) has clearly taken hold with the original poster without reason. Whether the window has been properly sealed remains unclear as well.
In the end, I don’t want to argue whether to use a simple membrane with studs towards the wall or a drainage membrane with studs away from the wall (or even the simple studded membrane away from the wall plus an additional fleece). The few centimeters difference hardly matters cost-wise.
But that is only a small part of the “problem” being discussed.
Bauherrin123 schrieb:
To be honest, the inspector was just trying to scare you in regards to the developer, Thanks for the best joke I’ve read here in over one hundred months of being a forum member!
If your husband has done self-performed work like applying slurry coatings, I don’t believe this is a developer but rather a general contractor building your house.
Your issue is not a technical one—apparently the work on site was done correctly—but a psychological and intellectual one: the intellectual part is your mistaken belief that the foundation slab has to be completely sealed against moisture; and the psychological part is your panic, which makes you deaf to receiving reassurance about the proper execution, to the point where you even “correct” the experienced respondents. You don’t need to worry about your foundation slab, everything is fine there. However, as has already been mentioned, the protection of the floor structure against moisture intrusion must not be neglected. The critical points here are the front door, terrace doors, and floor-to-ceiling windows, where the edge insulation should be sealed against the soil to prevent heavy or driving rain from causing problems.
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Bauherrin12323 Jun 2025 14:36Hello everyone,
First of all, I need to gather the information because I can’t remember all the details. The inspector will get back to me this evening. It’s not that I have overlooked your questions or didn’t respond, I simply don’t have the information yet.
A bitumen coating and slurry were applied. Over the weekend, I had three craftsmen here, and each told me something different, which left me a bit confused. While my concerns may seem high, the actual situation isn’t as bad. However, sometimes I couldn’t follow everything, since I’m not an expert.
I don’t have a basement; there is a bitumen coating and slurry applied. That is definitely not enough. I believe the developer should have at least installed a dimpled membrane or a waterproofing membrane or something similar to protect the ground slab. That way, nothing further would need to be done on the exterior facade of the house. This is part of the standard procedure in house construction.
It would have been better if, instead of a coating, a bitumen membrane had been used – that would make it waterproof, and just a dimpled membrane would then be sufficient. According to this forum, though, slurry and bitumen coating might also be enough. That’s the question now, since I’ve received different opinions.
Since the dimpled membrane mainly serves as mechanical protection, it only makes sense if there is a properly waterproof barrier underneath. This would be a bitumen membrane. Slurry and bitumen coating are not sufficient for that.
I’m not trying to find faults or necessarily have problems with the house, so please excuse me if I have difficulty understanding. Maybe someone here can explain your opinion once more. Is what I have now enough? Does it just need the dimpled membrane added, or does it require waterproofing with a bitumen membrane as well to be properly moisture-proof? I’ve had companies on site and many people who contacted me privately, so I was confused. Please also excuse the repeated questions; if anyone is annoyed, feel free not to respond, but I would appreciate avoiding personal attacks.
Regarding the window, nothing was done except the bitumen layer and slurry. I didn’t know anything else was required there either.
First of all, I need to gather the information because I can’t remember all the details. The inspector will get back to me this evening. It’s not that I have overlooked your questions or didn’t respond, I simply don’t have the information yet.
A bitumen coating and slurry were applied. Over the weekend, I had three craftsmen here, and each told me something different, which left me a bit confused. While my concerns may seem high, the actual situation isn’t as bad. However, sometimes I couldn’t follow everything, since I’m not an expert.
I don’t have a basement; there is a bitumen coating and slurry applied. That is definitely not enough. I believe the developer should have at least installed a dimpled membrane or a waterproofing membrane or something similar to protect the ground slab. That way, nothing further would need to be done on the exterior facade of the house. This is part of the standard procedure in house construction.
It would have been better if, instead of a coating, a bitumen membrane had been used – that would make it waterproof, and just a dimpled membrane would then be sufficient. According to this forum, though, slurry and bitumen coating might also be enough. That’s the question now, since I’ve received different opinions.
Since the dimpled membrane mainly serves as mechanical protection, it only makes sense if there is a properly waterproof barrier underneath. This would be a bitumen membrane. Slurry and bitumen coating are not sufficient for that.
I’m not trying to find faults or necessarily have problems with the house, so please excuse me if I have difficulty understanding. Maybe someone here can explain your opinion once more. Is what I have now enough? Does it just need the dimpled membrane added, or does it require waterproofing with a bitumen membrane as well to be properly moisture-proof? I’ve had companies on site and many people who contacted me privately, so I was confused. Please also excuse the repeated questions; if anyone is annoyed, feel free not to respond, but I would appreciate avoiding personal attacks.
Regarding the window, nothing was done except the bitumen layer and slurry. I didn’t know anything else was required there either.
Bauherrin123 schrieb:
Maybe someone can explain to me again what your opinion on this is. This request has so far only been fulfilled twice or three times.
Bauherrin123 schrieb:
then several who wrote to me privately, This wouldn’t be possible here at all – hence the question about where else you are posting.
Bauherrin123 schrieb:
I can do without personal attacks. There were none directed at you, and @nordanney will respond to your reproaches by refraining from helping you in the future. Hopefully you won’t drive away @derdietmar as well.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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