Cost of Slab Foundation Vs. Post/Pier Foundation

[donohued]

I am looking to have a foundation built for a small cabin (12' X 24' ). How much should I expect to pay for a 12" thick slab foundation? How about concrete piers (12 piers)? Thanks for the help.

[Rich]

I thought I had answered this.. I must've been dreaming.
For the slab you're probably looking at around 2500 for materials and labor. For the drilled piers (I assume they would be drilled anyway) you're probably looking at about the same. Drilled piers not only have the concrete (although quite a bit less) but they also need a drill rig to mobilize, layout, and drill them. Then drop the rebar cages and pour.

[roger g]

Here in the small town that I live in, they use huge vacuum trucks that suck out holes for the concrete. A man stands off to one side with a high pressure water line squirting into the hole to help. They were putting all new street lights down our main street and needed piers to hold the poles. I had never seen this before. It seemed very fast though an auger works fast also. One day I'll ask why they use this method.

roger

[Rich]

The main reason they do that is to not disturb or damage telephone lines, gas lines, sewer, etc. I've seen similar things done when looking for obstructions underground before excavation - called it pot holing.

[donohued]

Thanks for the information. I got an estimate for cement piers (12 of them) about a foot to two feet high. The contractor said between around $6,500. I thought that seemed pretty high. I'll have to get a second estimate. I a slab is around the same price I'm going to probably go that way.

[Rich]

Depending on where you are located and what the soil conditions are - you may need it more than 2'. I'm not sure what your requirements are for movement and that type of thing.. but if they are just set on the ground at 1'-2' high I would worry about movement.
What you could do to cheapen it up for yourself, if you're not too worried about a DIY project. Rent an 8" 2 man post hole digger and drill the piers 3-4' deep. Put a couple verticals in there and pour the concrete.. making sure the tops are all pretty close to level. You would probably need to use sonotube to get them out of the ground a foot or so. Then when you go to put your floor in you'll need some glu-lam beams to span from pier to pier and to hang the floor joists off. Just an idea.