24 x 36 Foundation & Block In : Slab Questions

[regularguysc]

Hello,

Not sure I'm uploading all the photos correctly, but we'll see.

My 24 x 36 build started last week (yeah!). Foundation was poured and block is in. Grading, plumbing and electrical rough in, block fill, and slab pouring is next.

Question 1 : The block will need to be sealed as part of it will be below grade. The surrounding soil in SC is really sandy. The contractor wants to use black roof type tar to seal. They've also used a Locktight product in the past. They said they had to redo a Thompson water seal product, so they stopped using that. My question is whether or not the black roof type tar will be good enough? They will be filling in the block, which the mason said will basically stop any moisture seepage along with the tar. Any comments / experiences are welcome.

Question 2 : They are not planning on putting down any rebar for the slab. They will grade, lay clay, compact, and then pour a 6 inch slab using fiber reinforced concrete. The floor will be polished after pouring. They say this works fine. I do plan on putting a lift in the garage. Is no rebar going to work? I've always heard that you need rebar, so I'm skeptical, but I'm not the expert.

 

[46Nash]

I am currently building a similar sized garage and planning on a lift. I am doing 6" 3500 PSI concrete with rebar. Fiber is not rebar and does not provide the same benefits.

Check the specs for your desired lift to make sure you get the right slab, as now is the time to get it right.

 

[Gary S]

I built a 24x48 garage on a 1 piece floating slab with no walls around it in 2004. My local building inspector told me that I needed to use EITHER rebar or fiber concrete, and either way I needed to make relief cuts in a slab that size to control cracks. I chose to use only fiber with no rebar.
Eight years later, the only cracks are on the relief cuts, and this is a 4" thick floor that every year deals with temperatures from -40 in winter to +110 in summer.
Fiber works! I fully believe the inspector knew his stuff.

You are on different soil and have different weather, so I recommend asking a local building inspector in your area.

 

[regularguysc]

Thanks for the feedback. Just moved to SC last year, I'm thinking our temperature swings are more like 30 - 100. Everyone down here freaks out if it gets below freezing and the weather reporters put out dire warnings. My wife and I are both from Chicago and find the whole situation humorous.

 

[jrsulo]

Thanks for the feedback. Just moved to SC last year, I'm thinking our temperature swings are more like 30 - 100. Everyone down here freaks out if it gets below freezing and the weather reporters put out dire warnings. My wife and I are both from Chicago and find the whole situation humorous.

Wait till it snows,and ya see how they drive in it !!!!!