Concrete question

[71buickfreak]

I am planning a new shop build, and I need some advice. The shop will be 50x40, not sure of the structure design yet, but it will either be wood or metal!

Anyway, I am wanting to get the pad poured soon, but finances are limited. The soil where my house is located is very hard clay, it is damn near impossible to dig, I have had backhoes that can't break through. The point being, it is pretty damn solid and at the top of hill, so there aren't any drainage issues, either.

I am looking at a 4" slab with rebar. I can get that done for about $3600.

There have been two suggestions- full footer which would add like 3k or a thickened edge, which would add $1800.

I live in Oklahoma, Winter temps range average in the 30s, with occassional dips into the teens, rarely below 0. Summer temps in the triple digits from July through August, 60-75% humidity.

The question is, do I need the thickened edge?

 

[Stuart in MN]

Where do you live? A floating slab generally has thickened edges in parts of the country where the ground freezes in winter. We either have to do that or use a footing and foundation. I'm not sure what's required in warmer areas.

 

[ConCretin]

Personally, I would want the thickened edge. It provides additional strength where the structure bears and vehicles enter. The add'l cost seems a bit high though. You are paying $150/cy for the 4' slab and over $900/cy for the haunch. There is additional excavation required but even so. Presumably your contractor will need a piece of equipment to clear, grub and level the sub grade. An extra couple hours to dig the haunch shouldn't be more than a few hundred bucks. About the same labor to set an 8" form as a 4" form. Might be worth a conversation.

 

[NUTTSGT]

Even though it doesn't get seriously cold there, I'd go with the full footer for piece of mind. All it would take is one cold winter and make that floor heave and crack.

Maybe more guys from your area will chime in and advise what they have used and their experience.

 

[71buickfreak]

That's what I am hoping for, more imput and experience. I know a full footing would be better, but that will run me 10k, I have priced that out. I am still looking at contractors. I had one guy quote me 10k for the 4" slab and thickened edge, which seems outrageous. I know that concrete is $89 yard here.

 

[Cougar]

I have a 30 x 50 pole building on a floating slab with thickened edge.
Been up about 10 years so far no problems.

 

[ConCretin]

I'm in the concrete business and built myself a slab for a 28x32 garage a couple years ago. It was 5" thick with #4 bars at 12" on center. I dug a 7" haunch around the perimeter and ran 2 additional #4 bars in the bottom. I added #4 dowels for a 12" high concrete curb around the perimeter to get the wood framing up off the ground. It's been through several tough Maine winters and looks like new.
A haunched slab works fine for a stand alone structure on good ground. If it's attached you need to put it on frost walls.

 

[DIRTY DEEDS]

I live in Edmond ok. .. MY slab has a thickened edge and no problems but, my post are set 3' deep in concrete. I would say a thickened edge is safe here in ok since the ground is hard and winters are short ..my opinion. I did use 3500 fiber filled concrete..