Expert: Dan Griffin - 12/16/2010

Question
i want to build a small 500 sq ft cabin over a 2000 sq ft slab over basement.
How do i estimate a basement with a slab over basement? Is it needed to slab over
a basement ? or is there another way to cover it?

Answer
Kathy, I'm confused.

Sounds like an underground bunker with a little cabin on top.  

What are you estimating?  The concrete, the total labor and material figure, a turn key project?

If this basement/bunker is going to be 2000 SF, it will need columns and beams, concrete cannot make the spans alone.  Adequate design will require using a structural engineer.A bunker this size will require extensive waterproofing.  Depending on soil conditions (water, rock, etc), the excavation, drainage work, and waterproofing may be the expensive part of the project.  Depending on climate, there may be some major benefits to one of the insulation block designs.

If this is really a cabin with a basement and 2000 ft of slab around it, it is a totally different project.

Give me some more information and I will be happy to answer.