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Nico79Bln16 Apr 2024 07:50Hello everyone,
First of all, thank you for taking the time to read my question.
My partner and I are currently having a construction company prepare a quote for a 155m² (1,670 sq ft) urban villa. For the calculation of the foundation work, we submitted a soil report which shows that approximately 50-60cm (20-24 inches) of topsoil lie above the load-bearing soil. Today, the company called me and offered two options:
Option 1:
- Strip and store the topsoil on the property
- Fill the excavation with sand and compact it in layers
- Excavate trenches for strip foundations about 80 cm (31 inches) deep and pour concrete
- Pour a concrete slab on the strip foundations
- Dispose of the excavation material or spread it over the remaining property
Option 2:
- Only strip the turf layer
- Excavate trenches for strip foundations about 80 cm (31 inches) deep and pour concrete
- Pour a load-bearing concrete slab (according to them, significantly thicker with more reinforcement than in option 1)
Option 2 is said to be about 2,500 euros cheaper than option 1, plus lower disposal costs for the excavation because much less material is removed.
Has anyone worked with this type of foundation or have experience with it? I have never heard of building a foundation on topsoil. On the other hand, the weight of the slab is not supported by the topsoil but by the strip foundations, which reach down to the load-bearing soil layer. In the end, I don’t want to risk damage to the entire house to save a few thousand euros.
Google hasn’t been much help. I only find information about strip foundations with non-load-bearing slabs or load-bearing slabs alone — both, of course, on load-bearing soil.
Thank you very much!
First of all, thank you for taking the time to read my question.
My partner and I are currently having a construction company prepare a quote for a 155m² (1,670 sq ft) urban villa. For the calculation of the foundation work, we submitted a soil report which shows that approximately 50-60cm (20-24 inches) of topsoil lie above the load-bearing soil. Today, the company called me and offered two options:
Option 1:
- Strip and store the topsoil on the property
- Fill the excavation with sand and compact it in layers
- Excavate trenches for strip foundations about 80 cm (31 inches) deep and pour concrete
- Pour a concrete slab on the strip foundations
- Dispose of the excavation material or spread it over the remaining property
Option 2:
- Only strip the turf layer
- Excavate trenches for strip foundations about 80 cm (31 inches) deep and pour concrete
- Pour a load-bearing concrete slab (according to them, significantly thicker with more reinforcement than in option 1)
Option 2 is said to be about 2,500 euros cheaper than option 1, plus lower disposal costs for the excavation because much less material is removed.
Has anyone worked with this type of foundation or have experience with it? I have never heard of building a foundation on topsoil. On the other hand, the weight of the slab is not supported by the topsoil but by the strip foundations, which reach down to the load-bearing soil layer. In the end, I don’t want to risk damage to the entire house to save a few thousand euros.
Google hasn’t been much help. I only find information about strip foundations with non-load-bearing slabs or load-bearing slabs alone — both, of course, on load-bearing soil.
Thank you very much!
Hello,
you basically already mentioned it yourself. When construction costs exceed €500,000, saving about €2,500 on the foundation does not seem wise. I would prefer option 1, as this ensures that the slab is supported everywhere and permanently (organic material can decompose). If moisture ever gets under the slab, sand is also better than topsoil.
you basically already mentioned it yourself. When construction costs exceed €500,000, saving about €2,500 on the foundation does not seem wise. I would prefer option 1, as this ensures that the slab is supported everywhere and permanently (organic material can decompose). If moisture ever gets under the slab, sand is also better than topsoil.
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