What's cheaper for total building costs, slab on grade or basement?

That’s a good question but a tough one. There are too many variables to give you a cut and dry answer. Many builders will tell you basements are cheaper - and maybe they are, mostly if you build them wrong.

Most basements are not properly sealed against moisture, they are poorly insulated, and prone to rot due to the standard practices of basement construction. I would read here first on our pros and cons page – 

Choosing between a slab on grade and a basement, which is better and cheaper?

If you were to build a basement properly with proper drainage, exterior waterproof membranes and insulate it well on all surfaces (including below footings which pretty much never happens), the cost would be a lot more than the standard basement. By ‘standard’ I mean, the ones where 2x4s are slapped onto a concrete wall, filled with fiberglass batts and covered with plastic so they stay wet and turn into oatmeal in about a decade. 

Basements require the building of a subfloor, and means loss of interior space as well as the cost of building stairs. Basically its like this – complexity costs money. The more simple you design it the cheaper it will be, and slabs are  more simple than basements. 

Personally you couldn’t really talk me into building a basement unless there was really no option. I prefer to be above ground, basements are always at risk of flooding, because – if you dig a hole, nature will try to fill it. That’s just the reality of this world. You can do your best to mitigate the risk of basement flooding with sumps etc, but that risk is always still there even if its small. See our page here on best practices for basement construction if you do end up going that route though.

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