ᐅ Basement or strip footing?

Hello,

we have now received the soil report for our plot and unfortunately didn’t hit the jackpot. The top 1.5m (5 feet) of soil needs to be completely replaced, and an additional 0.5m (20 inches) must be added to reach street level. This means at least 400 tons of material plus disposal of the excavated soil.

I’m currently estimating roughly 20,000 to 30,000 euros in additional costs, which isn’t a problem since we planned a sufficient buffer.

I’m considering whether strip foundations might be more practical and especially cheaper in this case (this is also listed as an option in the soil report). However, a structural engineer would probably need to calculate this first. Could you maybe provide a rough cost estimate based on a similar case?

Alternatively, I’m also thinking about reducing the size of the house a bit and instead having a full basement. Our general contractor said a waterproof concrete basement would cost at least 50,000 euros, but it would only be a utility basement.

What would you do?

Thanks

In the North, building without a basement always means using strip footings. This is completely normal and actually saves on excavation work. Feel free to follow this approach. There is no risk involved. K.

Hello,
In this case, I would build with a basement!
The prices are not clear to me; I don’t understand why a basement or earthworks should be so expensive.

Best regards

Earthworks themselves are not that expensive; the material and its removal are the main cost drivers. The general contractor charges €43 per ton (gross) based on weighbridge tickets (including delivery, compaction, and documentation). For a building footprint of 100 m² (1,076 ft²), 2 m (6.6 ft) deep, and about 2 tons per cubic meter, that quickly adds up to approximately €17,000, and the old soil still has to be disposed of somewhere.

With 0.5 m (1.6 ft) strip foundations, only about 40 m³ (52 yd³) of soil needs to be removed, but this requires more concrete, reinforcing steel, and formwork; however, less steel and concrete are needed in the slab foundation. I think this should be cheaper overall, but for now, it’s just a rough estimate.

We don’t have groundwater but do have waterlogging in the soil layers, which is why a waterproof concrete shell (“white tank”) is planned. I think the €50,000 estimate is realistic.

We’ll see—nothing has been signed yet, so there’s likely some room for negotiation.

Thanks so far.

How large should the basement be?