Expert: Michael Curry - 9/12/2007

Question
I have a single story house built on a concrete slab and would like to extend the footprint and add a one or two story addition.  Must my extension be built on a concrete slab as well, or can I use another type of foundation (i.e. concrete block)?  How would another type of foundation tie into the existing slab?

Answer
Hi Mike,

I would suggest you build the addition the same as the existing so that it looks as original as possible. If you build with blocks you will either have to frame a floor or pour a slab. Tieing in to the other slab will require some work to be done properly. You should drill holes into the side of the existing slab and epoxy in pieces of rebar. Ask the local building department for some advise on what others have done in your area. Lastly, make sure the ground is compacted well as settling is not good when attached to an existing structure.