Discussion Cost of foundation and prep work on a garage slab?

[Ajay]

So, the Mrs and I are refinancing our mortgage (rates are terrific). I'm doing some rough pricing checking on costs before the refi. The garage itself will be ~$20K (maybe a tad less depending on materials costs next year). I'm not sure how much it costs for a slab (say for a 22' square garage) is in New England. Anyone have a rough Idea.

The contractor we will be using is excellent, but he's been straight out this summer he hasn't had a chance to stop by - so I need to ball park it.

 

[herm0016]

figure 10 to 12 per sq foot for a 4 in slab with rebar and minimal grading. at least that's what it is around here.

not sure what you need foundation wise where ever you live.

 

[Ajay]

figure 10 to 12 per sq foot for a 4 in slab with rebar and minimal grading. at least that's what it is around here.

Thanks! Pretty much flat as a board and has asphalt for our off street parking already (which, obviously, will need to be removed).

 

[Greenman]

Slab is only part of the cost, you need a foundation as well.
I can't begin to guess at the cost because it sounds like you live in one of those places where water isn't liquid half the year.

 

[Ajay]

Slab is only part of the cost, you need a foundation as well.
I can't begin to guess at the cost because it sounds like you live in one of those places where water isn't liquid half the year.

Yes, well, 4 months below freezing. I can’t remember what it’s called, but the slab 'sits' on concrete columns poured 3+ feet deep to get below the frost line.

 

[Steltek]

Yes, well, 4 months below freezing. I can’t remember what it’s called, but the slab 'sits' on concrete columns poured 3+ feet deep to get below the frost line.

You mean a stem wall foundation for the slab?

 

[Greenman]

You mean a stem wall foundation for the slab?

Almost certainly. A suspended slab would eat a whole bunch of budget in a big hurry.

 

[Ajay]

Okay, I had the wrong type of slab installations for our climate. What is used up here is FSPF installation: http://buildipedia.com/aec-pros/con...ed-shallow-foundations-for-unheated-buildings. Man, I thought this would be simple - LOL!

 

[herm0016]

Almost certainly. A suspended slab would eat a whole bunch of budget in a big hurry.

usually just a stem wall/ perimeter wall 3 feet or so deep, you can monopour with the footing if you have the right forms. then build the garage on that, then pour a 4 in floating slab after its done. inside graded with roadbase. no need for a suspended slab with all that rebar and tie into the stem all.

i would consider a grade beam slab as well. depending on your frost depth.

that frost protected slab looks way more complicated than a grade beam slab or just digging a stem wall.

 

[Ajay]

Pics if this helps:






They can be mono-poured as @herm0016 mentioned. The DIY guys do two pours 'frost wall/footing" and separate slab. My contractor will sub that job out to one of a couple local concrete companies he does business with - so I'm sure they have all the right forms for slab foundations in NH.

Thanks for the input so far guys!

 

[Ajay]

i would consider a grade beam slab as well. depending on your frost depth.

32" though it's typically treated as 36" for construction purposes.