Basement - Cost of Partial or Entire Footprint of House

[Cheib]

We’re relatively advanced with a design for a new build house.  The design originally had a basement under the full extent of the house but we’ve reduced that to 2/3 because of the cost and the fact that we don’t really need the space. We’ve recently started meeting QS’s with the view to retaining one in the near future, one has made a comment that it could be a false economy to reduce the footprint as having a partial basement means that the foundations in the rest of the house need to be commensurate so you don’t really end up saving that much ? I can sort of see the logic in that but wondered if anyone had a view on it ?

 

 

[Oz07]

Makes sense doesn't it. Partial split level works on sloping ground but id prefer to be building upwards all off the same base. 

[ragg987]

We have a partial basement, but our ground floor is a split level and the semi-basement follows the split. Your QS may have a point - the build per sq ft will be higher for the smaller basement than if you increased it, however you will save money by reducing the footprint of the basement. If nothing else you are digging and hauling a lot less earth.

 

Your foundation where you do not have a basement will be cheaper than if you did have a basement.

[vivienz]

What's your ground like? If it's clay, beware of muckaway costs - they can be prohibitively expensive.

[Cheib]

We're in the Chilterns, ground is chalk/flint. We're on top of a hill so I think we're a good way above the water table.

 

Going to see if we can increase the above ground build so we can remove the need for a basement completely.  One option is building a garden room or similar under PD for the existing house before we demolish it (but after we've got planning for the new house).

 

As you say it does makes sense that it's more complex.

Edited May 13, 2019 by Cheib

[Bitpipe]

We did the full footprint basement, as it's a roughly square box it made sense.

 

When originally thinking about it, we got quotes for 1/4 and 1/2 basements - unsurprisingly they were not 1/4 or 1/2 of the price more like 1/3 and 2/3.

 

 

[Triassic]

Our house in L shaped, the basement is under the long leg of the L, the short leg of the L is a two storey section of the house. So in reality each of the two sections of the house is built directly above the foundations below, so no bits of house overhanging the foundations below, if you get my drift.