ᐅ Minimum height difference between the floor drain outlet and the finished floor level
Created on: 3 Oct 2012 15:58
C
cybercopAs part of the building permit / planning permission application for our new single-family house without a basement, the design office commissioned by the general contractor has planned a difference of 35 cm (14 inches) between the planned ground level and the top edge of the finished floor. This gap is considered absolutely necessary to prevent moisture problems later on due to the adjacent soil.
Since I find 35 cm (14 inches) to be relatively generous and this would result in a small platform with two steps at the main entrance, I would like to ask if it would be possible to reduce this large difference without causing the moisture issues the design office is concerned about.
Note:
According to the cross-section drawing, the ground floor construction consists of a concrete slab of 16 cm (6 inches) and a further buildup of 19 cm (7.5 inches).
If any additional information is needed to answer my question, please let me know.
Thank you in advance for your efforts.
Best regards,
Ralf
Since I find 35 cm (14 inches) to be relatively generous and this would result in a small platform with two steps at the main entrance, I would like to ask if it would be possible to reduce this large difference without causing the moisture issues the design office is concerned about.
Note:
According to the cross-section drawing, the ground floor construction consists of a concrete slab of 16 cm (6 inches) and a further buildup of 19 cm (7.5 inches).
If any additional information is needed to answer my question, please let me know.
Thank you in advance for your efforts.
Best regards,
Ralf
If no development plan specifies the arrangement of the finished floor level, the general contractor’s (GC) requirement is based on the following:
The plaster at ground level is usually applied as a splash water protection up to about 30 cm (12 inches) high, meaning it should be made with especially moisture-resistant material. However, this splash water protection does not have to be below the finished floor level.
According to technical building regulations, all exterior walls in contact with the ground must be sealed against moisture. Only approved waterproofing systems in accordance with DIN standards may be used for this purpose; plaster alone is not sufficient. Given the specified floor height of a 16 cm (6 inch) slab and a 19 cm (7.5 inch) floor build-up, the total height of 35 cm (14 inches) above the finished floor level requested by the GC is exactly met, meaning the outer walls would no longer be in contact with the soil. In such a case, vertical waterproofing might not be required—at least as far as the minimum technical requirements are concerned. It is possible they want to avoid this waterproofing. I consider the approach taken by the planner or GC to be unprofessional.
It is correct that, for example, in front of doors, the water-bearing layer must be at least 15 cm (6 inches) below the openings; this can also be ensured by using a grate or drainage channel. Therefore, it is technically feasible to create a level entrance.
Additionally, the 16 cm (6 inch) thickness of the slab seems rather tight. For reinforced concrete slabs, minimum concrete cover over the steel reinforcement must also be maintained, typically 2–3 cm (about 1 inch), depending on the situation and the substructure design. I recommend having the planning, especially the structural engineering, reviewed externally by qualified experts. Furthermore, careful attention must be paid to horizontal waterproofing during execution.
Regarding the GC’s stated requirement, I get the impression that the external vertical waterproofing is being avoided or that there is an attempt to provoke a cost increase. A GC or planner has no right to demand the floor height arrangement from you as described above; with appropriate measures, it is not necessary.
The plaster at ground level is usually applied as a splash water protection up to about 30 cm (12 inches) high, meaning it should be made with especially moisture-resistant material. However, this splash water protection does not have to be below the finished floor level.
According to technical building regulations, all exterior walls in contact with the ground must be sealed against moisture. Only approved waterproofing systems in accordance with DIN standards may be used for this purpose; plaster alone is not sufficient. Given the specified floor height of a 16 cm (6 inch) slab and a 19 cm (7.5 inch) floor build-up, the total height of 35 cm (14 inches) above the finished floor level requested by the GC is exactly met, meaning the outer walls would no longer be in contact with the soil. In such a case, vertical waterproofing might not be required—at least as far as the minimum technical requirements are concerned. It is possible they want to avoid this waterproofing. I consider the approach taken by the planner or GC to be unprofessional.
It is correct that, for example, in front of doors, the water-bearing layer must be at least 15 cm (6 inches) below the openings; this can also be ensured by using a grate or drainage channel. Therefore, it is technically feasible to create a level entrance.
Additionally, the 16 cm (6 inch) thickness of the slab seems rather tight. For reinforced concrete slabs, minimum concrete cover over the steel reinforcement must also be maintained, typically 2–3 cm (about 1 inch), depending on the situation and the substructure design. I recommend having the planning, especially the structural engineering, reviewed externally by qualified experts. Furthermore, careful attention must be paid to horizontal waterproofing during execution.
Regarding the GC’s stated requirement, I get the impression that the external vertical waterproofing is being avoided or that there is an attempt to provoke a cost increase. A GC or planner has no right to demand the floor height arrangement from you as described above; with appropriate measures, it is not necessary.
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