Good morning,
I have a problem. We are building a house with a Swedish slab foundation (load-bearing insulation under the concrete – only on one side is there a strip footing because of the garage attached to the house).
The earthworks company came and, in my opinion, made a mistake.
They excavated the ground according to the soil report down to the load-bearing layer and then backfilled and compacted it with F1 gravel up to street level, 1.9m (6.2 ft) high. BUT:
This bedding layer is only 50cm (20 inches) wider than the house footprint all around.
(The house measures 11.5 x 9m (38 x 30 ft) / The foundation bedding is 12.5 x 10m (41 x 33 ft))
I had heard a long time ago that a foundation bedding should always be larger than the house dimensions by the height of the bedding layer on each side.
So the bedding would need to measure 15.3 x 12.8m (50 x 42 ft) here.
My architect says I should ask the structural engineer. The structural engineer says I should clarify it with the slab manufacturer. – The manufacturer says the earthworks company should know everything. GREAT. Everyone leaves me hanging, and I bet they all know the answer.
In parallel, I have hired an expert who can only come to the site on 27.01. Until then, construction is stopped.
The earthworks company says it’s sufficient because my house won’t be as heavy as others since I’m building with wood and the slab distributes the load evenly into the ground and not at a typical load transfer angle – so they don’t admit any fault.
I’m asking cautiously here in advance if anyone can share experience about what might happen, or if someone has encountered a similar situation.
Thanks and best regards
I have a problem. We are building a house with a Swedish slab foundation (load-bearing insulation under the concrete – only on one side is there a strip footing because of the garage attached to the house).
The earthworks company came and, in my opinion, made a mistake.
They excavated the ground according to the soil report down to the load-bearing layer and then backfilled and compacted it with F1 gravel up to street level, 1.9m (6.2 ft) high. BUT:
This bedding layer is only 50cm (20 inches) wider than the house footprint all around.
(The house measures 11.5 x 9m (38 x 30 ft) / The foundation bedding is 12.5 x 10m (41 x 33 ft))
I had heard a long time ago that a foundation bedding should always be larger than the house dimensions by the height of the bedding layer on each side.
So the bedding would need to measure 15.3 x 12.8m (50 x 42 ft) here.
My architect says I should ask the structural engineer. The structural engineer says I should clarify it with the slab manufacturer. – The manufacturer says the earthworks company should know everything. GREAT. Everyone leaves me hanging, and I bet they all know the answer.
In parallel, I have hired an expert who can only come to the site on 27.01. Until then, construction is stopped.
The earthworks company says it’s sufficient because my house won’t be as heavy as others since I’m building with wood and the slab distributes the load evenly into the ground and not at a typical load transfer angle – so they don’t admit any fault.
I’m asking cautiously here in advance if anyone can share experience about what might happen, or if someone has encountered a similar situation.
Thanks and best regards
The expert clearly stated that he cannot comment on the load distribution angle; he said that in the report he only has to point out that it must be observed.
The fill material was specified by the foundation slab. It was called F1 gravel, compacted every 20cm (8 inches). (The report states "base course material – gravel" – the civil engineer said it is the same.)
I gave the instructions to the civil engineer and the expert. But always after consulting with everyone else, so I have not made a single decision on my own.
The fill material was specified by the foundation slab. It was called F1 gravel, compacted every 20cm (8 inches). (The report states "base course material – gravel" – the civil engineer said it is the same.)
I gave the instructions to the civil engineer and the expert. But always after consulting with everyone else, so I have not made a single decision on my own.
We installed a load distribution angle approximately 80 cm (31.5 inches) wide. 50 cm (20 inches) would have sufficed.
Our civil engineer was actually a professional (and complied with #-Safety), and if it were as you claim, our foundation wouldn’t have fit on the plot in some places. So, honestly, I consider that to be a rumor.
If the backfilling with gravel was done according to the soil report’s requirements, it should be fine at your construction site for a timber frame house.
Regards
Thorsten
PS: When installing gas, water, and electricity, the local authorities at the time placed everything just 5 cm (2 inches) from the house wall. Incredible! They completely destroyed the angle on one side over a length of more than 4 m (13 feet). It was a huge hassle until they repaired everything and rerouted it properly…..
Our civil engineer was actually a professional (and complied with #-Safety), and if it were as you claim, our foundation wouldn’t have fit on the plot in some places. So, honestly, I consider that to be a rumor.
If the backfilling with gravel was done according to the soil report’s requirements, it should be fine at your construction site for a timber frame house.
Regards
Thorsten
PS: When installing gas, water, and electricity, the local authorities at the time placed everything just 5 cm (2 inches) from the house wall. Incredible! They completely destroyed the angle on one side over a length of more than 4 m (13 feet). It was a huge hassle until they repaired everything and rerouted it properly…..
A building consultant from RWE once told us this some time ago. Apparently, it also depends on the height of the foundation bedding. If you have 80cm (31.5 inches) of bedding around your house, you will have at most 80cm (31.5 inches) of fill, right?
This is also stated in an RWE soil report.
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Good day,
link removed; please observe the forum rules.
Thank you!
Bauexperte
This is also stated in an RWE soil report.
---------------------
Good day,
link removed; please observe the forum rules.
Thank you!
Bauexperte
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