Hello,
I am trying my luck again, although the response to my previous questions has been almost zero.
We want to extend an existing semi-detached house (with a basement) by adding an extension that will also have a basement.
Now both the architect and the builder are wondering how and in what way the support of the neighbouring house needs to be ensured.
Proposal:
1. Set back the neighbor’s basement by 1 meter (3 feet 3 inches), meaning shortening it, and pour the foundation slab against the semi-detached house.
2. Stabilize the walls of the neighboring house somehow more securely (sheet piling??)
What would something like this cost, and how complex is it?
Who is actually responsible for ensuring this? Shouldn’t a semi-detached house be designed so that the other side can be extended without issues?
Thanks
Hilaria
I am trying my luck again, although the response to my previous questions has been almost zero.
We want to extend an existing semi-detached house (with a basement) by adding an extension that will also have a basement.
Now both the architect and the builder are wondering how and in what way the support of the neighbouring house needs to be ensured.
Proposal:
1. Set back the neighbor’s basement by 1 meter (3 feet 3 inches), meaning shortening it, and pour the foundation slab against the semi-detached house.
2. Stabilize the walls of the neighboring house somehow more securely (sheet piling??)
What would something like this cost, and how complex is it?
Who is actually responsible for ensuring this? Shouldn’t a semi-detached house be designed so that the other side can be extended without issues?
Thanks
Hilaria
B
Bauexperte8 Nov 2011 11:01Hello,
There is actually nothing to wonder about, because...
… this costs roughly the same amount—apart from losing living space—as
supporting the existing building on the property line. Foundations can only be built on "natural ground level"; if this is not available, it has to be created. The moment your excavation contractor moves the excavator, they alter the natural (in this case presumably compacted) soil…
Your architect and/or builder should not have to worry about this—it is the structural engineer’s job, based on the soil report results.
That depends on factors such as the size and age of the neighboring half, the materials used there, what the soil report states, what the structural engineer determines, and more… but additional costs of around 5,000 euros plus extra are easily expected.
It is always the responsibility of the party building second; this is one of the main reasons why complete semi-detached houses in new developments are best built simultaneously by the same contractor.
You are responsible for ensuring that the existing property does not suffer any damage; you must commission the appropriate securing measures through your builder. Were you not informed about this in advance? If it helps, building without a basement generally requires investing even more money.
Kind regards
Hilaria schrieb:
We want to extend an existing semi-detached house (with a basement), also adding a basement. Now both the architect and the builder are wondering how and in what way the support of the neighboring house needs to be ensured.
There is actually nothing to wonder about, because...
Hilaria schrieb:
Suggestion
1. Move the neighbor’s basement back by about 1m (3 feet), and pour the foundation slab connected to the semi-detached house
… this costs roughly the same amount—apart from losing living space—as
Hilaria schrieb:
2. Reinforce the walls of the neighbor’s house in some way (sheet piling??)
supporting the existing building on the property line. Foundations can only be built on "natural ground level"; if this is not available, it has to be created. The moment your excavation contractor moves the excavator, they alter the natural (in this case presumably compacted) soil…
Your architect and/or builder should not have to worry about this—it is the structural engineer’s job, based on the soil report results.
Hilaria schrieb:
How much does something like this cost and how complex is it?
That depends on factors such as the size and age of the neighboring half, the materials used there, what the soil report states, what the structural engineer determines, and more… but additional costs of around 5,000 euros plus extra are easily expected.
Hilaria schrieb:
Who is responsible for this? Shouldn't a semi-detached house be designed so that the other half can be extended without any problems?
It is always the responsibility of the party building second; this is one of the main reasons why complete semi-detached houses in new developments are best built simultaneously by the same contractor.
You are responsible for ensuring that the existing property does not suffer any damage; you must commission the appropriate securing measures through your builder. Were you not informed about this in advance? If it helps, building without a basement generally requires investing even more money.
Kind regards
@Jimmy80, unfortunately I don’t understand your post at all.
@Bauexperte, why would building without a basement be even more expensive?
The other semi-detached house has been standing for about 6 years and measures 8 x 8.50 meters (26 x 28 feet).
“You can only build on natural ground,” could you please explain that a bit more?
Why is moving away from the boundary just as expensive? Of course, some space is lost...
Thank you.
@Bauexperte, why would building without a basement be even more expensive?
The other semi-detached house has been standing for about 6 years and measures 8 x 8.50 meters (26 x 28 feet).
“You can only build on natural ground,” could you please explain that a bit more?
Why is moving away from the boundary just as expensive? Of course, some space is lost...
Thank you.
B
Bauexperte8 Nov 2011 23:25Hello,
Because then you would have to support the entire length of the existing house down to the basement level. Such a stepped foundation easily costs around EUR 10,000 (+/-).
The term natural ground level generally refers to the undisturbed or “grown” soil surface, meaning the existing terrain that has not been artificially changed by excavation or fill.
For natural ground level, there are, for example, specific regulations in North Rhine-Westphalia regarding reasonable adjustments (§ 9 Building Code NRW).
First, for that reason; second, you also have to support the floor slab at the ground floor on the parts in contact with the soil, as if there was nothing underneath.
However, I consider the EUR 2,000 per linear meter mentioned by my predecessor to be an overestimate; nevertheless, it is not cheap.
Kind regards
Hilaria schrieb:
@Bauexperte, why would building without a basement be even more expensive?
The other semi-detached house has been standing for about 6 years and measures 8 x 8.50 meters (26 x 28 feet).
Because then you would have to support the entire length of the existing house down to the basement level. Such a stepped foundation easily costs around EUR 10,000 (+/-).
Hilaria schrieb:
"Foundations can only be built on natural ground," can you explain this a bit more?
The term natural ground level generally refers to the undisturbed or “grown” soil surface, meaning the existing terrain that has not been artificially changed by excavation or fill.
For natural ground level, there are, for example, specific regulations in North Rhine-Westphalia regarding reasonable adjustments (§ 9 Building Code NRW).
Hilaria schrieb:
Why is moving back just as expensive? Of course, space is lost...
First, for that reason; second, you also have to support the floor slab at the ground floor on the parts in contact with the soil, as if there was nothing underneath.
However, I consider the EUR 2,000 per linear meter mentioned by my predecessor to be an overestimate; nevertheless, it is not cheap.
Kind regards
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