Concrete Strength

[KPSquared]

So, I am building a new garage here shortly. At this point it's going to be 30x30.

I am wondering what you guys would reccomend for my floor. I got a quote on 20 mpA and 25 mpA concrete but have had reccomendations for 28 mpA and re-bar grid at 12" centers.

Looking for good advice or point me in the direction of an exisiting thread...

I plan to install a 2 post hoist, but I will lay footings for that, so how thick, and how tough does my shop floor need to be?

(sorry if this has been covered a 1000 times... I can't find relevant threads)

 

[royale5]

You can get many different suggestions or options so here is mine:

4000psi should cover you for cars or pick up trucks. If you plan on working on any heavy equipment you could bump it up. Do you know what size bar you are going to use? 12" OC might be overkill. You should be just fine with a 6x6 wire mesh sheet. The footers around the lift posts can get some #4 bar to help with the point loads.

 

[KYGTP]

I am getting ready to pour my floor in my garage in a week or so and I am going with a 5" pour using 3500psi concrete. I am using rebar in my floor, # 4 12 OC in the both directions. My pour will be 49 x 42 ish so I think that is why they went with the rebar, tell you the truth, I really don't know why. I will be installing a lift as well and according to Ben-Pak, you need a min of 4" pour using 3500 psi concrete, so I know that I will be good to go.

It seems that alot of people on here like to pour footers for the lift, but I think some of it may be a little over kill, but I can see where you would want to be safe than sorry. At this point I don't know exactly where I want my lift, so to be commited to a spot is a little hard for me right now. Plus, I don't plan on using the lift all the time like a full time shop would, so I think I will be OK with what I have. Just my .02 though.

Oh, and Good luck on your build, BTW!!

 

[red]

KYGTP
When I poured my basement floor the mason did a continuous footing for the lolly columns. This way I could put the columns any where along the center of the slab. If you have a ball park area for your lift you can do the same. The mason was paid by the yard so "extra" concrete was not an issue.

 

[Shocker]

6" 4500psi, rebar and grid.

 

[LegacyIndustrial]

Go with Shocker's recommendation and add fiber.
It makes a bigger difference than you would think.

 

[KPSquared]

I realize this is an old thread, but my garage got put off until this spring. I'm back in planning phase now...

Would I really need 6" or 4500psi, rebar AND grid (I assume he means 6x6 wire mesh?)

That totally seems like way overkill for the scope of my project.

This is a 30x36 home garage. Biggest rig I'll ever have in there is my 2001 F350 or whatever fullsize pickup I get next.

That just seems like way to much floor and unnecessary cost for what I'm doing.

 

[Cobra6]

6" 4500psi, rebar and grid.

That's what I did today on my 24' x 36' pad for my garagemahal.

 

[bczygan]

The strength of the concrete is how hard it will be and resistant to loads per square inch. The rebar ties the whole slab into one monolithic 2-way multi-directional beam that will span any differences in the supporting capacity of the subgrade and fill material. The wire mesh will help prevent any minor cracking in the concrete as it cures (FG fibers do this too). Much more than I am used to putting into production homes. But you guys are wanting slabs that will hold loads and stay perfect for finishes. What is the cost difference?

 

[KPSquared]

The cost difference in what? The only recent numbers I have here are for 20mpa and 25mpa concrete.

20 mpa is about $183/cubic meter
25 mpa is about $190/cubic meter

So that would be in imperial...um...

2900 psi = $238/yard
3600 psi = $247/yard

I assume that you ad fibre and more strength, the price is gonna go up accordingly.

Don't know the cost of fibre or mesh. 10 mil rebar around here is about $5.40 for 19.5' length.

i think my numbers are right...