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": That is a very good decision!
If a horizontal damp-proof course was installed below or between the masonry units (this is not only necessary for ground-contact slabs), it also indicates that the designer anticipated rising damp and aims to prevent moisture from spreading capillarily onto the wall surfaces through this measure.
Although I am not a lawyer, should the unlikely event occur (let’s hope it doesn’t, and that the architect—if our concerns are justified—will be open to revising their planning), your documentation and approach could potentially give you a very strong position!
---------------------------
I personally wish you success with your next steps!!
Best regards: KlaRa
If a horizontal damp-proof course was installed below or between the masonry units (this is not only necessary for ground-contact slabs), it also indicates that the designer anticipated rising damp and aims to prevent moisture from spreading capillarily onto the wall surfaces through this measure.
Although I am not a lawyer, should the unlikely event occur (let’s hope it doesn’t, and that the architect—if our concerns are justified—will be open to revising their planning), your documentation and approach could potentially give you a very strong position!
---------------------------
I personally wish you success with your next steps!!
Best regards: KlaRa
Thanks KlaRa!
Now I just want to quickly ask one final question.
If I can’t manage the flame-applied bitumen option, then the spray-applied version is probably better in comparison to not applying any waterproofing at all, right? It still creates a layer several millimeters thick (a few tenths of an inch) that provides a waterproofing effect, doesn’t it?
Best regards and have a nice Sunday!
Now I just want to quickly ask one final question.
If I can’t manage the flame-applied bitumen option, then the spray-applied version is probably better in comparison to not applying any waterproofing at all, right? It still creates a layer several millimeters thick (a few tenths of an inch) that provides a waterproofing effect, doesn’t it?
Best regards and have a nice Sunday!
Hello "joho78",
In your initial question from January 26, 2017 (quote: "Plumbers and electricians are currently busy"), you mentioned that all installation conduits are probably already installed and fixed on the rough slab.
This means that bonding a bituminous membrane waterproofing (flame application is only done on the roof) will no longer be possible. For this, a continuously shot-blasted, dust-extracted (by vacuum) and bitumen-primed concrete surface is required.
These preparations are also necessary for liquid waterproofing.
However, these are not standardized and must therefore be classified as special constructions (except for bitumen thick coatings, which are also only approved for external surfaces) and must be coordinated and approved with the client before application. The planner cannot and must not simply decide to use these on their own!
--------------------
The "spray method," as you call it, is therefore also not applicable. Especially in the described initial situation, thickness control and consistent application (ensuring functionality and tightness) cannot be carried out or verified at all.
Such an execution would violate professional standards, so you should avoid specifying or even accepting such a variant!!!
What is still possible as a functional emergency solution with installed installations (certainly no credit to the planner) I have already described:
Surface waterproofing with sheet membranes, vapor-tight bonded at overlaps, connected to the horizontal damp-proof course of the wall surfaces.
The visual disorder that results after completion of the installation can only be leveled with a bound, water-free screed base.
On top of this continuous layer, the thermal insulation boards of the calculated necessary thickness are installed, followed by a PE foil as penetration protection against the mixing water of the wet screed, and then the 45mm (1.75 inches) thick screed as standard screed (or at least 60mm (2.36 inches) if heated screed).
This way, the situation can be managed as a functional execution.
------------------------------------
Note: These explanations do not constitute legally binding advice, as I have only derived the local situation from the description provided.
Good luck: KlaRa
In your initial question from January 26, 2017 (quote: "Plumbers and electricians are currently busy"), you mentioned that all installation conduits are probably already installed and fixed on the rough slab.
This means that bonding a bituminous membrane waterproofing (flame application is only done on the roof) will no longer be possible. For this, a continuously shot-blasted, dust-extracted (by vacuum) and bitumen-primed concrete surface is required.
These preparations are also necessary for liquid waterproofing.
However, these are not standardized and must therefore be classified as special constructions (except for bitumen thick coatings, which are also only approved for external surfaces) and must be coordinated and approved with the client before application. The planner cannot and must not simply decide to use these on their own!
--------------------
The "spray method," as you call it, is therefore also not applicable. Especially in the described initial situation, thickness control and consistent application (ensuring functionality and tightness) cannot be carried out or verified at all.
Such an execution would violate professional standards, so you should avoid specifying or even accepting such a variant!!!
What is still possible as a functional emergency solution with installed installations (certainly no credit to the planner) I have already described:
Surface waterproofing with sheet membranes, vapor-tight bonded at overlaps, connected to the horizontal damp-proof course of the wall surfaces.
The visual disorder that results after completion of the installation can only be leveled with a bound, water-free screed base.
On top of this continuous layer, the thermal insulation boards of the calculated necessary thickness are installed, followed by a PE foil as penetration protection against the mixing water of the wet screed, and then the 45mm (1.75 inches) thick screed as standard screed (or at least 60mm (2.36 inches) if heated screed).
This way, the situation can be managed as a functional execution.
------------------------------------
Note: These explanations do not constitute legally binding advice, as I have only derived the local situation from the description provided.
Good luck: KlaRa
Hello KlaRa!
Thanks for the detailed description. I have a quick technical question regarding the "surface waterproofing as sheet membrane": Since the installations are now complete and fixed to the floor, is the membrane applied and sealed over the pipes? Shouldn't there be a layer of filling material underneath (I understand there should be one above)? Otherwise, wouldn't there be an air gap forming beneath these sheets?
Best regards
Thanks for the detailed description. I have a quick technical question regarding the "surface waterproofing as sheet membrane": Since the installations are now complete and fixed to the floor, is the membrane applied and sealed over the pipes? Shouldn't there be a layer of filling material underneath (I understand there should be one above)? Otherwise, wouldn't there be an air gap forming beneath these sheets?
Best regards
The membrane waterproofing is not a stretch film. It can largely follow surface irregularities. However, a loose filling layer under the membrane is definitely possible; there is no reason against it. The downside of this method is that the leveling layer or loose fill must be walked on again afterward to lay the membrane. Unfortunately, this often happens rather carelessly. As a result, footprints usually appear in the already leveled fill, creating depressions. Once the membrane is installed above, it is no longer possible to access this layer for corrections.
While smaller depressions should ideally be avoided, according to the flatness standard DIN 18202 Table 3, Row 2 (for raw concrete ceilings, which are usually the base for thermal insulation elements), this is not critical. After all, the thermal insulation and the screed (due to its thickness) adequately and safely cover any possible unevenness.
None of this is so crucial as long as the thermal insulation is placed above the waterproofing layer!
So: both methods, filling above or below (in relation to a membrane waterproofing), have been used in practice, and both work. One requires somewhat more effort, the other somewhat less.
Best regards, KlaRa
While smaller depressions should ideally be avoided, according to the flatness standard DIN 18202 Table 3, Row 2 (for raw concrete ceilings, which are usually the base for thermal insulation elements), this is not critical. After all, the thermal insulation and the screed (due to its thickness) adequately and safely cover any possible unevenness.
None of this is so crucial as long as the thermal insulation is placed above the waterproofing layer!
So: both methods, filling above or below (in relation to a membrane waterproofing), have been used in practice, and both work. One requires somewhat more effort, the other somewhat less.
Best regards, KlaRa
K
Knallkörper30 Jan 2017 15:35How do you assess the impact of a possible membrane beneath the ground slab (blinding layer) on the need for a horizontal waterproofing layer above the slab? Minimal, moderate, or none?
Similar topics