ᐅ Requirements for the foundation slab – any experiences?

Created on: 11 Jun 2013 18:56
D
Dali
D
Dali
11 Jun 2013 18:56
Hello,

we plan to build a 1.5-story house of about 133 sqm (1,432 sq ft) without a basement, approximately 9 by 10 m (30 by 33 ft).

When reading the construction specification (excerpt below), the slab on grade seemed very thin to me, as other providers offer slab thicknesses of up to 25 cm (10 inches).

Is the slab on grade as described sufficient?

Excerpt from the construction specification:

"Earthworks:
The topsoil will be removed to a depth of 30 cm (12 inches), and the excavated soil will remain on the property. The missing height will be replaced with frost-resistant material. Depending on geotechnical requirements, the foundation bedding will be increased up to 45 cm (18 inches). A separating layer of plastic sheeting will be installed on the frost-resistant material. Conduits for utility supply to the house connection room will be routed the shortest way to 50 cm (20 inches) before the exterior wall.

Slab on grade:
The slab will be constructed according to the drawing with a thickness of 16 cm (6.3 inches) using steel fiber-reinforced concrete of concrete quality C25/30. A grounding strip made of galvanized steel tape will be installed. An additional moisture barrier against ground moisture will be applied on top of the slab.

Floor:
The floor in the living areas is designed as a floating screed with perimeter strips on thermal and impact sound insulation. The build-up is as follows:
Ground floor:
approximately 85 mm (3.3 inches) thermal insulation (PS rigid foam, WLG 035)
PE foil
approximately 45 mm (1.8 inches) cement screed
If higher impact sound insulation requirements apply according to DIN, this will be adjusted."

Thank you very much for your help!
Y
ypg
11 Jun 2013 19:22
The construction specifications outline what is included in the price.
The thickness of the foundation slab and the corresponding excavation are determined based on the geotechnical report, so it is possible—and quite likely—that additional costs will arise.
16cm (6.3 inches) sounds very thin to a layperson like me.
B
Bauqualle
11 Jun 2013 20:24
Dali schrieb:

16cm (6.3 inches) steel fiber reinforced concrete with a concrete grade of C25/30
.. steel fiber reinforced concrete at 16cm (6.3 inches) thickness is also problematic, since only steel fibers are used and no steel mesh reinforcement ... that makes a difference ...
Dali schrieb:

Floor: Ground floor: approx. 85mm (3.3 inches) thermal insulation (PS rigid foam, WLG 035), PE foil, approx. 45mm (1.8 inches) cement screed
.. the ratio is also problematic .. > 85/45 and then no reinforcement .... the screed will almost certainly crack and/or sag later ....
B
BratacDD
12 Jun 2013 09:22
Hello,
I am only familiar with such slabs used in combination with strip foundations. The wall loads are transferred directly into the ground through these. The floor slab is essentially non-load-bearing and reinforced structurally with steel fibers.
Regards, Ronny