Hello everyone,
At our house built in 2010, we noticed a few centimeters above the terrace stones that the plaster is efflorescing. Digging around all four exterior sides revealed that the waterproofing layer made of bitumen, shown on the construction drawings between the foundation and the masonry, is missing. Regardless of the cause, responsibility, fraud, or whatever else, I would like to inquire about the necessary work to be done here. The opinions I've received so far vary widely.
Here is how I currently assess the required work:
I look forward to your answers and thank you in advance.
Best regards
vaincare
At our house built in 2010, we noticed a few centimeters above the terrace stones that the plaster is efflorescing. Digging around all four exterior sides revealed that the waterproofing layer made of bitumen, shown on the construction drawings between the foundation and the masonry, is missing. Regardless of the cause, responsibility, fraud, or whatever else, I would like to inquire about the necessary work to be done here. The opinions I've received so far vary widely.
Here is how I currently assess the required work:
- Expose the foundation all around (This can be done by oneself – including breaking through the door portal. But how deep? According to the drawings, the waterproofing must extend to 20cm (8 inches) below the top edge of the foundation. Is that sufficient? Is it also necessary to waterproof from the inside, meaning beneath the strip footing up to under the supported slab?)
- Drying time (How long? If the masonry and plaster are really damp, this should be factored in, right?)
- Waterproofing (Priming, applying bitumen membrane from a roll or similar, possibly multiple layers. Can this be done by oneself, or should a professional company be hired?)
- Backfilling and everything should be fine...
I look forward to your answers and thank you in advance.
Best regards
vaincare
Hello everyone,
I cannot confirm whether a waterproofing slurry was actually applied. We only recently took over the house and have no construction diary information... unfortunately, this cannot be verified now as it is covered with plaster.
There is no insulation applied on top; the porous concrete blocks provide good insulation.
With this post, I am also sharing some pictures:
1.) Damage overview
2.) Plan excerpt (red marking = instruction for bitumen, blue marking = detail of foundation-to-plinth plaster transition)
3-6) Exposed transition areas without bitumen.
I hope the pictures provide a clear impression.
Best regards
vaincare

I cannot confirm whether a waterproofing slurry was actually applied. We only recently took over the house and have no construction diary information... unfortunately, this cannot be verified now as it is covered with plaster.
There is no insulation applied on top; the porous concrete blocks provide good insulation.
With this post, I am also sharing some pictures:
1.) Damage overview
2.) Plan excerpt (red marking = instruction for bitumen, blue marking = detail of foundation-to-plinth plaster transition)
3-6) Exposed transition areas without bitumen.
I hope the pictures provide a clear impression.
Best regards
vaincare
Is the protruding concrete the strip foundation?
Otherwise, you need to distinguish between the building structure waterproofing (in your case the [not visible] bitumen) and the moisture protection of the base (plaster) (which you do not have, no idea if it is necessary with this type of plaster).
Otherwise, you need to distinguish between the building structure waterproofing (in your case the [not visible] bitumen) and the moisture protection of the base (plaster) (which you do not have, no idea if it is necessary with this type of plaster).
Hello everyone,
since this thread has been quiet for a while, I’d like to ask again if anyone has any comments for me based on the pictures.
I’m currently having doubts about whether I really need to apply bitumen waterproofing around the entire house as a vertical barrier. I believe that the base coat plaster is waterproof. Therefore, at most, only the bottom row of the masonry will get damp, since there is a horizontal barrier (or at least there should be one) on top of it. The absorbent exterior plaster only starts above that.
I appreciate any feedback.
Best regards
vaincare
since this thread has been quiet for a while, I’d like to ask again if anyone has any comments for me based on the pictures.
I’m currently having doubts about whether I really need to apply bitumen waterproofing around the entire house as a vertical barrier. I believe that the base coat plaster is waterproof. Therefore, at most, only the bottom row of the masonry will get damp, since there is a horizontal barrier (or at least there should be one) on top of it. The absorbent exterior plaster only starts above that.
I appreciate any feedback.
Best regards
vaincare
To me, it already looks like the building waterproofing on the plan isn’t extended high enough. I also can’t see any render or base waterproofing.
What kind of experts did you consult? Are you sure you understood everything correctly? You must not backfill directly against the bitumen waterproofing!
What kind of experts did you consult? Are you sure you understood everything correctly? You must not backfill directly against the bitumen waterproofing!