ᐅ Basement or slab foundation? – Cost estimation

Created on: 12 Oct 2020 16:02
T
Thirteen
Hello dear forum,

After much consideration, we have finally decided on a house.
It will be 175 sqm (1,884 sq ft) for a family of five.

We are still debating: basement or slab-on-grade?

We have a slightly sloped plot and are weighing which option would be the best in the end. The basement would be a utility basement, incorporating a double garage, a workshop, and a storage room.

The alternative would be to build on a slab-on-grade with a double garage plus storage/shed space.

Since we are building on a slight slope, we are thinking about what costs to expect for each option. Of course, excavation costs are hard to predict, but maybe someone can estimate. Two excavation contractors have already examined the site and said that both basement and slab-on-grade are possible without problems. However, no one wants to give us a rough cost estimate, which complicates things.

Our idea was that with the basement including two garages, we might save some costs for slope retaining. Building on a slab, plus a double garage, plus higher costs for slope retaining might end up in a similar price range. We wouldn’t have much storage space inside the house.

The quotes we have are as follows:
Slab-on-grade 17,000 + 25,000 for double garage including foundation + total X for excavation work.
Basement 45,000 + 20,000 for finishing + total X for excavation work.

Could anyone give an assessment of which option seems more sensible?

Construction plan snapshot: green areas, orange blocks, blue outlines, measurement lines.
A
Amel_NRW
11 Jan 2021 12:43
@JoachimG.: Dennert offered us slightly thinner waterproof concrete walls and was therefore the most affordable. So, it is only comparable if the scope of services is similar.
It is best to specify yourself (or have the architect specify) exactly what should be offered.