ᐅ Is the concrete slab, masonry, and insulation all in good condition?
Created on: 27 Sep 2022 22:32
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DominicHannoveD
DominicHannove27 Sep 2022 22:32Hello,
I would like to get your opinion on an offer we have received. First of all: the developer is "quite" affordable compared to the market, so I understand that we are not being offered the absolute best. Nevertheless, I would like to know if what is offered basically meets today’s standard for house construction. Below are some excerpts from the building specification.
Regarding earthworks
...The topsoil in the area of the building footprint will be excavated to a depth of up to 30 cm (12 inches) and stored on-site for reuse on the property. Fill sand up to 30 cm (12 inches) thick will be placed and compacted in the foundation pit. Trenches for the strip foundations will be excavated, and the excavated soil will be stored on the property. Any additional earthworks required due to local conditions are to be agreed upon and compensated separately.
Foundation and drainage
The wastewater pipes will be laid under the ground slab using KG pipes with an average diameter of 100 mm (4 inches), running the shortest route to the outside edge of the house.
The foundation will be a shallow foundation with a reinforced concrete ground slab including continuous, unreinforced strip footings. The ground slab will be 20 cm (8 inches) thick, reinforced with two layers of steel reinforcement mesh Q 257A and poured with concrete of grade C 20/25. A dimpled membrane will be installed as a cleanliness layer and capillary break.
A foundation grounding conductor made of galvanized strip steel will be installed according to VDE regulations.
Masonry
Exterior walls with plaster façade will be constructed with a total thickness of approximately 33.0 cm (13 inches) as follows: 17.5 cm (7 inches) perforated clay bricks (product Unipor) plus about 15.5 cm (6 inches) external thermal insulation composite system including white pigmented, textured façade plaster.
Exterior walls with facing brickwork will be about 45 cm (18 inches) thick in total, consisting of 17.5 cm (7 inches) perforated clay bricks (product Unipor), approximately 14 cm (5.5 inches) mineral fiber cavity insulation, a 2 cm (0.8 inch) ventilation gap, and 11.5 cm (4.5 inches) facing bricks. Window and door lintels will be covered with galvanized steel angles. The brick size is standard format with a material cost up to 600.00 €/1,000 pieces including VAT. The joints of the facing brickwork will be raked out and subsequently pointed in cement gray.
Knee walls, if applicable, will be built solidly according to the structural plans, either in masonry or reinforced concrete.
Interior walls on the ground and upper floors will also be built solidly from perforated clay bricks. The clear structural height on the ground floor is about 2.64 m (8 ft 8 in) and approximately 2.665 m (8 ft 9 in) on the upper floor.
Damp-proofing against ground moisture
The horizontal damp-proof course against rising ground moisture below the external walls will be installed using bitumen sheets. The remaining area of the ground slab will be sealed with bitumen torch-on membranes.
All exterior surfaces of the perimeter walls will be waterproofed against lateral moisture up to 30 cm (12 inches) above ground level. For facing brickwork, the waterproofing takes place behind the facing bricks on the outside of the backup wall.
Drywall work
The ceilings and sloping roof areas on the upper floor will be insulated with mineral wool according to the thermal protection certificate, sealed with a vapor barrier foil, and clad with gypsum plasterboards on battens.
The knee walls will also be clad with gypsum plasterboards on a metal stud frame. The gypsum boards will be finished with joint filler and fasteners to standard quality level Q2, suitable for applying textured wallpaper. Joints between individual components, e.g. gable wall and ceiling, must be sealed elastically by the painter using acrylic sealant.
Screed work
A calcium sulfate screed will be laid level and smooth. Underfloor insulation will be installed on the ground floor according to the thermal protection certificate, and approximately 80 mm (3 inches) impact sound insulation will be installed on the upper floor.
The total floor construction height is approximately 19 cm (7.5 inches) on the ground floor and about 14 cm (5.5 inches) on the upper floor.
Do the above features generally correspond to a KFW-55 house?
I would appreciate any advice 🙂
I would like to get your opinion on an offer we have received. First of all: the developer is "quite" affordable compared to the market, so I understand that we are not being offered the absolute best. Nevertheless, I would like to know if what is offered basically meets today’s standard for house construction. Below are some excerpts from the building specification.
Regarding earthworks
...The topsoil in the area of the building footprint will be excavated to a depth of up to 30 cm (12 inches) and stored on-site for reuse on the property. Fill sand up to 30 cm (12 inches) thick will be placed and compacted in the foundation pit. Trenches for the strip foundations will be excavated, and the excavated soil will be stored on the property. Any additional earthworks required due to local conditions are to be agreed upon and compensated separately.
Foundation and drainage
The wastewater pipes will be laid under the ground slab using KG pipes with an average diameter of 100 mm (4 inches), running the shortest route to the outside edge of the house.
The foundation will be a shallow foundation with a reinforced concrete ground slab including continuous, unreinforced strip footings. The ground slab will be 20 cm (8 inches) thick, reinforced with two layers of steel reinforcement mesh Q 257A and poured with concrete of grade C 20/25. A dimpled membrane will be installed as a cleanliness layer and capillary break.
A foundation grounding conductor made of galvanized strip steel will be installed according to VDE regulations.
Masonry
Exterior walls with plaster façade will be constructed with a total thickness of approximately 33.0 cm (13 inches) as follows: 17.5 cm (7 inches) perforated clay bricks (product Unipor) plus about 15.5 cm (6 inches) external thermal insulation composite system including white pigmented, textured façade plaster.
Exterior walls with facing brickwork will be about 45 cm (18 inches) thick in total, consisting of 17.5 cm (7 inches) perforated clay bricks (product Unipor), approximately 14 cm (5.5 inches) mineral fiber cavity insulation, a 2 cm (0.8 inch) ventilation gap, and 11.5 cm (4.5 inches) facing bricks. Window and door lintels will be covered with galvanized steel angles. The brick size is standard format with a material cost up to 600.00 €/1,000 pieces including VAT. The joints of the facing brickwork will be raked out and subsequently pointed in cement gray.
Knee walls, if applicable, will be built solidly according to the structural plans, either in masonry or reinforced concrete.
Interior walls on the ground and upper floors will also be built solidly from perforated clay bricks. The clear structural height on the ground floor is about 2.64 m (8 ft 8 in) and approximately 2.665 m (8 ft 9 in) on the upper floor.
Damp-proofing against ground moisture
The horizontal damp-proof course against rising ground moisture below the external walls will be installed using bitumen sheets. The remaining area of the ground slab will be sealed with bitumen torch-on membranes.
All exterior surfaces of the perimeter walls will be waterproofed against lateral moisture up to 30 cm (12 inches) above ground level. For facing brickwork, the waterproofing takes place behind the facing bricks on the outside of the backup wall.
Drywall work
The ceilings and sloping roof areas on the upper floor will be insulated with mineral wool according to the thermal protection certificate, sealed with a vapor barrier foil, and clad with gypsum plasterboards on battens.
The knee walls will also be clad with gypsum plasterboards on a metal stud frame. The gypsum boards will be finished with joint filler and fasteners to standard quality level Q2, suitable for applying textured wallpaper. Joints between individual components, e.g. gable wall and ceiling, must be sealed elastically by the painter using acrylic sealant.
Screed work
A calcium sulfate screed will be laid level and smooth. Underfloor insulation will be installed on the ground floor according to the thermal protection certificate, and approximately 80 mm (3 inches) impact sound insulation will be installed on the upper floor.
The total floor construction height is approximately 19 cm (7.5 inches) on the ground floor and about 14 cm (5.5 inches) on the upper floor.
Do the above features generally correspond to a KFW-55 house?
I would appreciate any advice 🙂
S
SaniererNRW12327 Sep 2022 23:23DominicHannove schrieb:
Do the above-mentioned features actually represent a KFW-55 house?Your energy consultant or builder will definitely be able to confirm that. We cannot. Which windows, which heating system, which ventilation, which roof insulation, and so on?
DominicHannove schrieb:
I am currently in contact with buildersDominicHannove schrieb:
the builder is "fairly" affordable compared to industry standards,You mean a building contractor (here probably specifically a general contractor). A developer would only offer you the complete package of house and land, not construction on your own plot.Choose one who has a good reputation above all else – these are usually local or regional companies.
DominicHannove schrieb:
excavation up to 30 cm deep and [...] fill sand up to 30 cm thick is placed and compacted.From a layperson’s perspective, this reads as: “great, this much is included” – but from a professional standpoint: “30 cm is included – what is the cost beyond 31 cm?” At a glance, the mentioned offer is within the usual range. Offering two wall constructions (essentially one for those who prefer one option and another for a different preference) is quite common, and the described variants are average without particular features going significantly up or down. Technically, I don’t see any reason in your description to warn you or to congratulate you on an outstanding deal.In general, advice can be given with accuracy that depends on how much or how little we know about your project (currently: quite little).
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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WilderSueden28 Sep 2022 10:50Just a quick overview...
- Earthworks are a common clause. You will have problems if 30cm (12 inches) is not enough, whether due to slope, soil bearing capacity, or frost protection.
- Drainage might be less than optimal. The shortest path to the outer edge is not necessarily toward the sewer shaft, and from the outer edge onwards, it is probably your responsibility. It would be better to combine everything and have one pipe running toward the shaft.
- Are you building with brick veneer or a rendered facade? 60 cents per brick seems quite low to me; a quick Google search suggests you should rather expect around 1€ per brick.
- Room height is the rough construction dimension, so you still have to subtract the floor construction everywhere.
- The different floor heights for the upper floor and ground floor confuse me a bit. Where exactly is your thermal building envelope? Apparently, the slab itself is not insulated, and this is compensated by a high floor construction?
- Earthworks are a common clause. You will have problems if 30cm (12 inches) is not enough, whether due to slope, soil bearing capacity, or frost protection.
- Drainage might be less than optimal. The shortest path to the outer edge is not necessarily toward the sewer shaft, and from the outer edge onwards, it is probably your responsibility. It would be better to combine everything and have one pipe running toward the shaft.
- Are you building with brick veneer or a rendered facade? 60 cents per brick seems quite low to me; a quick Google search suggests you should rather expect around 1€ per brick.
- Room height is the rough construction dimension, so you still have to subtract the floor construction everywhere.
- The different floor heights for the upper floor and ground floor confuse me a bit. Where exactly is your thermal building envelope? Apparently, the slab itself is not insulated, and this is compensated by a high floor construction?
X
xMisterDx29 Sep 2022 23:09Different floor heights between the upper floor and the ground floor are normal. On the upper floor, thermal insulation beneath the screed is not required, only impact sound insulation, to which the underfloor heating is fastened.
On the ground floor, thermal insulation is added underneath, apparently about 5cm (2 inches).
You won’t have any issues with the foundation; it will just be a bit more expensive.
It would also be more costly if you hired a general contractor (GC) whose price includes the foundation, as this would then be reflected in a higher overall house price.
On the ground floor, thermal insulation is added underneath, apparently about 5cm (2 inches).
You won’t have any issues with the foundation; it will just be a bit more expensive.
It would also be more costly if you hired a general contractor (GC) whose price includes the foundation, as this would then be reflected in a higher overall house price.
Overall, the insulation does not seem sufficient to meet the KfW-55 standard (if I recall correctly, mandatory from 01.01?). Even the Building Energy Act barely complies. However, I could be mistaken. It might also be that the person responsible for the thermal protection verification calculates precisely and does not use flat rates, which often allows for less insulation.
That was done the same way for me, but I was told "at the shopping center around the corner" that this does not comply with the Eurocode (which is not mandatory anyway). Your slab is probably not a structural element (considered a cheap construction method). However, no one there could explain how many years earlier my house would potentially fail.
I recommend consulting a qualified expert who reviews the construction specifications before signing any contract.
DominicHannove schrieb:
A dimpled damp-proof membrane is installed as a cleanliness layer and capillary break.
That was done the same way for me, but I was told "at the shopping center around the corner" that this does not comply with the Eurocode (which is not mandatory anyway). Your slab is probably not a structural element (considered a cheap construction method). However, no one there could explain how many years earlier my house would potentially fail.
I recommend consulting a qualified expert who reviews the construction specifications before signing any contract.
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