Hello!
I’m interested in your opinion again.
In about one week, the screed will be poured (plumbers and electricians are currently busy). Now the following issue has come up:
- We don’t have a horizontal damp proof membrane on the slab (no basement) and the screed installer has pointed out that this apparently does not comply with the standards.
- We don’t have a horizontal damp proof membrane because the builder said it wasn’t necessary since we have a 40 cm (16 inches) capillary-breaking layer (Geocell foam glass gravel). This was also recorded in the contract protocol and the construction meeting minutes.
- The architect also confirmed the non-necessity with a building physics calculation, which is documented in the construction meeting minutes.
=> Our concern now is what, for example, the insurance company would say in case of a pipe leak. Could they refer to the standard and possibly reduce the payout in case of damage, even though the non-necessity was confirmed by our professionals?
Here is the structure again (as mentioned, no basement, so directly on the ground):
200 mm (8 inches) gravel
400 mm (16 inches) foam glass gravel (capillary-breaking)
200 mm (8 inches) concrete
110 mm (4.3 inches) EPS granulate
70 mm (2.75 inches) cement screed
10 mm (0.4 inches) tiles
What do you think? Should we definitely add a damp proof membrane?
Best regards
Jochen
I’m interested in your opinion again.
In about one week, the screed will be poured (plumbers and electricians are currently busy). Now the following issue has come up:
- We don’t have a horizontal damp proof membrane on the slab (no basement) and the screed installer has pointed out that this apparently does not comply with the standards.
- We don’t have a horizontal damp proof membrane because the builder said it wasn’t necessary since we have a 40 cm (16 inches) capillary-breaking layer (Geocell foam glass gravel). This was also recorded in the contract protocol and the construction meeting minutes.
- The architect also confirmed the non-necessity with a building physics calculation, which is documented in the construction meeting minutes.
=> Our concern now is what, for example, the insurance company would say in case of a pipe leak. Could they refer to the standard and possibly reduce the payout in case of damage, even though the non-necessity was confirmed by our professionals?
Here is the structure again (as mentioned, no basement, so directly on the ground):
200 mm (8 inches) gravel
400 mm (16 inches) foam glass gravel (capillary-breaking)
200 mm (8 inches) concrete
110 mm (4.3 inches) EPS granulate
70 mm (2.75 inches) cement screed
10 mm (0.4 inches) tiles
What do you think? Should we definitely add a damp proof membrane?
Best regards
Jochen
@ "joho78":
Tip: Save the money for the alternative waterproofing (which is the correct term), as it cannot lead to any success!
The installations passing through the structural slab must be secured against displacement.
This means: inevitably drilling through the foundation slab, penetrating the waterproofing layer.
As a result, it becomes perforated and can no longer perform its intended functions.
Those who do not listen and try to install waterproofing on a DIY basis will have to live with the disadvantages later! Because at a later stage, the mistakes made now can no longer be undone.
----------------
Regards, KlaRa
Tip: Save the money for the alternative waterproofing (which is the correct term), as it cannot lead to any success!
The installations passing through the structural slab must be secured against displacement.
This means: inevitably drilling through the foundation slab, penetrating the waterproofing layer.
As a result, it becomes perforated and can no longer perform its intended functions.
Those who do not listen and try to install waterproofing on a DIY basis will have to live with the disadvantages later! Because at a later stage, the mistakes made now can no longer be undone.
----------------
Regards, KlaRa
@ "joho78": A liquid waterproofing cannot be properly applied if conduit pipes or plumbing pipes for sanitary installations have already been fixed or laid on the concrete slab.
The same applies if the installations are planned to be done after applying the alternative waterproofing (liquid waterproofing)!
If you say, "... I don’t want to take any risks here ...", then this planned approach is definitely not suitable to prevent the risk of later damage and/or an unfavorable indoor climate (due to constant moisture) caused by moisture rising through the concrete slab!
You can ignore these warnings if you wish, but when it comes to STRUCTURAL ENGINEERING as well as WATERPROOFING, expertise in building physics is required—not advice that you can simply read off a packaging label from a hardware store!
But the decision is yours.
I am not writing these lines out of boredom or a need for attention to put something on paper.
I am writing this because I am well aware from my expert practice of the disadvantages I would like to help you avoid.
Because sooner or later exactly what I have predicted will happen.
And then there will be no possibility for you to correct this wrong path.
--------------------
Regards, KlaRa
The same applies if the installations are planned to be done after applying the alternative waterproofing (liquid waterproofing)!
If you say, "... I don’t want to take any risks here ...", then this planned approach is definitely not suitable to prevent the risk of later damage and/or an unfavorable indoor climate (due to constant moisture) caused by moisture rising through the concrete slab!
You can ignore these warnings if you wish, but when it comes to STRUCTURAL ENGINEERING as well as WATERPROOFING, expertise in building physics is required—not advice that you can simply read off a packaging label from a hardware store!
But the decision is yours.
I am not writing these lines out of boredom or a need for attention to put something on paper.
I am writing this because I am well aware from my expert practice of the disadvantages I would like to help you avoid.
Because sooner or later exactly what I have predicted will happen.
And then there will be no possibility for you to correct this wrong path.
--------------------
Regards, KlaRa
Hello KlaRa! Thank you for your detailed explanation, and believe me, I appreciate your opinion, otherwise I wouldn’t have asked the forum for advice! Furthermore, I am working with professionals in this matter (e.g., hygrothermal calculations by our architect), but I am also happy to get other opinions.
So now back to the question: In your opinion, what is the technically optimal waterproofing against rising moisture (water vapor diffusion)? Best regards
So now back to the question: In your opinion, what is the technically optimal waterproofing against rising moisture (water vapor diffusion)? Best regards
Hello "joho78".
Just to say: I also advise architects concerning floor constructions. Even when, as in this case, a large project was incorrectly planned so that you could see the cross-section of the screed through the low-level window panes from outside...
--------------
In your case, it is probably only about damage limitation.
Most likely (but you should verify this yourself) the lower rows of bricks in both interior and exterior walls do not rest on a horizontal damp-proof course (if not yet plastered, you can usually spot the edges of the damp-proof membranes there).
This means: even if the surface is currently sealed, rising moisture could still travel up the edges of the walls.
However: there is no need to worry.
If the current situation is that a ground-contact concrete slab is already fitted with all installation conduits and the interior walls are in place, the only option is to use a membrane waterproofing (sheet membrane) with sufficiently overlapping and vapor-proof joints sealed with appropriate adhesive tape.
Although this looks “improper” and causes difficulties in installing insulation boards (impact sound insulation can be neglected as described), this is the only way to “get things under control.”
The weak points will be at the floor-to-wall junctions, where the waterproofing layer should normally connect to the horizontal damp-proof course following professional standards.
The primary question to clarify is: Is there a horizontal damp-proof course on the masonry (at the first or second brick row), YES or NO.
All attempts to use a liquid applied waterproofing will fail in this initial situation because proper application with a defined, consistent layer thickness is impossible!
------------------
Best regards, KlaRa
Just to say: I also advise architects concerning floor constructions. Even when, as in this case, a large project was incorrectly planned so that you could see the cross-section of the screed through the low-level window panes from outside...
--------------
In your case, it is probably only about damage limitation.
Most likely (but you should verify this yourself) the lower rows of bricks in both interior and exterior walls do not rest on a horizontal damp-proof course (if not yet plastered, you can usually spot the edges of the damp-proof membranes there).
This means: even if the surface is currently sealed, rising moisture could still travel up the edges of the walls.
However: there is no need to worry.
If the current situation is that a ground-contact concrete slab is already fitted with all installation conduits and the interior walls are in place, the only option is to use a membrane waterproofing (sheet membrane) with sufficiently overlapping and vapor-proof joints sealed with appropriate adhesive tape.
Although this looks “improper” and causes difficulties in installing insulation boards (impact sound insulation can be neglected as described), this is the only way to “get things under control.”
The weak points will be at the floor-to-wall junctions, where the waterproofing layer should normally connect to the horizontal damp-proof course following professional standards.
The primary question to clarify is: Is there a horizontal damp-proof course on the masonry (at the first or second brick row), YES or NO.
All attempts to use a liquid applied waterproofing will fail in this initial situation because proper application with a defined, consistent layer thickness is impossible!
------------------
Best regards, KlaRa
Hello KlaRa!
Thank you very much for your time! Regarding your questions: Yes, the first row of bricks is equipped everywhere with horizontal waterproofing (bitumen). I will now forward your comment to our architect, as the bitumen spray coating is scheduled for the end of next week and thus could theoretically still be "stopped" (if not advisable). I’m curious to hear what he will say.
Thanks
Kind regards
Jochen
Thank you very much for your time! Regarding your questions: Yes, the first row of bricks is equipped everywhere with horizontal waterproofing (bitumen). I will now forward your comment to our architect, as the bitumen spray coating is scheduled for the end of next week and thus could theoretically still be "stopped" (if not advisable). I’m curious to hear what he will say.
Thanks
Kind regards
Jochen
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