Hello,
we are building a single-family house, two floors, approximately 160 sqm (1,722 sq ft). According to the soil report, we need to dig down to 1.4 m (4.6 ft). In addition, a frost barrier according to DIN standards must be installed, or alternatively a frost-resistant bedding under the foundation slab (which is not DIN compliant).
"The installation of a frost barrier can be omitted if frost-resistant and frost-safe material, such as natural crushed stone, basalt lava, or clay-free gravel with a graded grain size of 0/45, is used and compacted for the necessary ground filling."
Our general contractor recommends basalt lava or crushed stone (as requested in the excavation subcontractor form) compacted in layers under the foundation slab, since the soil is soft. He advises against the frost barrier because interruptions in the bedding can potentially lead to settling.
However, basalt is far too expensive. As an alternative, the excavation contractor suggests mountain gravel (frost protection gravel, locally common with report), which is also affordable.
We are now uncertain: first, a bedding that is not DIN compliant, and second, gravel that often contains clay, report or not... The foundation is probably the most important part of the construction, or are we being too critical?
What would you recommend?
Regards,
body123
we are building a single-family house, two floors, approximately 160 sqm (1,722 sq ft). According to the soil report, we need to dig down to 1.4 m (4.6 ft). In addition, a frost barrier according to DIN standards must be installed, or alternatively a frost-resistant bedding under the foundation slab (which is not DIN compliant).
"The installation of a frost barrier can be omitted if frost-resistant and frost-safe material, such as natural crushed stone, basalt lava, or clay-free gravel with a graded grain size of 0/45, is used and compacted for the necessary ground filling."
Our general contractor recommends basalt lava or crushed stone (as requested in the excavation subcontractor form) compacted in layers under the foundation slab, since the soil is soft. He advises against the frost barrier because interruptions in the bedding can potentially lead to settling.
However, basalt is far too expensive. As an alternative, the excavation contractor suggests mountain gravel (frost protection gravel, locally common with report), which is also affordable.
We are now uncertain: first, a bedding that is not DIN compliant, and second, gravel that often contains clay, report or not... The foundation is probably the most important part of the construction, or are we being too critical?
What would you recommend?
Regards,
body123
C
Caspar202013 Jul 2018 06:31body123 schrieb:
frost-resistant bedding under the concrete slab (which is not compliant with DIN standards).Who says that this is not compliant with DIN standards?
body123 schrieb:
secondly, gravel is usually clayey, I see; why is that? When I order gravel, I get this type.
What speaks against crushed stone?
Simply placing a house on a gravel bed is often done. It’s cheap, but actually not proper if it is above the frost-protected depth. The DIN standards (there are 2-3 of them) don’t really provide a clear statement on this, so the claim that it would not comply with DIN is incorrect.
The assertion that a frost skirt causes different settlements is equally nonsense... you have quite an impressive builder…
The assertion that a frost skirt causes different settlements is equally nonsense... you have quite an impressive builder…
@Casper2020
The geotechnical report states that this measure (padding) does not comply with the DIN standard EN1997-1:2009-09 / DIN regulation 1054:2010-12, p.40, and that the client must be informed and agree to it.
So far, gravel has not been offered to us, and I am not exactly sure what is meant by gravel. Basalt gravel is also gravel, right?
@Lumpi_LE
Why is gravel padding considered problematic?
Would it be more sensible to install a frost protection footing with basalt padding? That might be even more expensive...
Regards
Body
The geotechnical report states that this measure (padding) does not comply with the DIN standard EN1997-1:2009-09 / DIN regulation 1054:2010-12, p.40, and that the client must be informed and agree to it.
So far, gravel has not been offered to us, and I am not exactly sure what is meant by gravel. Basalt gravel is also gravel, right?
@Lumpi_LE
Why is gravel padding considered problematic?
Would it be more sensible to install a frost protection footing with basalt padding? That might be even more expensive...
Regards
Body
The mentioned standard, applied to your issue, states: "If you omit a frost skirt, the insulation must be frost-resistant." It would only be non-compliant with the standard if the insulation is not frost-resistant. But here lies the problem, which is why I say "it’s flawed," because no one can truly guarantee that this is the case, or that it will remain so.
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