Concrete slab thickness for vehicle lift? (And some great concrete suggestions!)


Are you on the Garage Journal forum, Paul? It’s a really good one for questions like this. Dozens of threads on the subject and a lot of helpful folk who have BTDT.


Kapitis Indagatoris
Are you on the Garage Journal forum, Paul? It’s a really good one for questions like this. Dozens of threads on the subject and a lot of helpful folk who have BTDT.
Thanks. It's been a while since I've been over there, but great suggestion.


Active member
Here in the Pacific Nothwest I lay down 2 layers of the heaviest poly I can buy then tape all the seams with construction sheething tape. Interior slabs are insulated with XPS (extruded poly styrene).

Rebar is best when it is in the bottom half of (1 1/2" chairs) of the slab. This places the rebar in tension when the slab is loaded.

I use a 12"grid of 10M (3/8") rebar and sometimes fiber (interior slabs) to help to prevent cracking. Fibers that are sticking up afterwards need to be sanded or burned (propane torch) off.

10M rebar splices are overlapped 18" or more.

I'll manually tie with double loop ties or rent a cordless.

41unBObbjmL._SX300_QL70_.jpg (300×266)

When tying the rebar either use 2 wire ties that are 90 degrees to each other at each cross or alternate the angle from one to the next. Ties all at the same angle will pull the rebar out of square.

I'll bend the ends of the rebar at the perimiter of the slab past 90 degree with a 3"-4" tail but this
is not nessary.

Once the grid is tied take measuments of the rebar from a reference point. This helps when drilling holes in the slab at a later date.

If you layout the grid at exactly the desired spacing (line the ends up and use a square to mark each with a grease pencil.....don't use chalk it rubs off) then all you need is the measurement to the 1st bar.

Best to use large rock but if a pump is used the large rock will plug up smaller (cheaper) line pumps but not a larger boom (truck) pump.

Order extra concrete if a pump is used.

Don't overwork the finish and keep it covered or flooded with water.


Man On a Mission
We in the final design phases on our outbuilding and I'll be installing a two post vehicle lift. The manufacturer recommends slab thickness of 4 inches. We're pouring 5 inches for the entire floor. I'd love to hear from those that have done this and if you have any advice/suggestions? And any advice/suggestions on lift placement or "I wish I had done this......". Much appreciated!
The standard for a concrete slab just for parking a Car on should be 4 to 6" and for vehicles of 2 to 3.5 Ton it should be 6 to 8" and for 3.5 to 5 Ton it should be around 8 to 10",

If you are going to fit a Hoist/Lift then you will want at leased 6 to 8" because all the weight is placed in a small area which will place a heck of a lot of stress on the concrete below the base plates, Personally I would be aiming for 8 to 10", And I would use fibreglass reinforced Concrete but just watch out getting it on your skin because it can bring you out in sores because what ever they put in it effects 3 out of 5 people

hope that helps.


Kapitis Indagatoris
Thanks for the info! Had my first site inspectionthat went well. Now waiting on the satellite LIDAR examination to determine what's under our forest/historic site. Fun...


In the UK minimum rebar splice is commonly 40 times the bar diameter. Pour at 3 degrees C and rising as a minimum unless you're covering it and or heating it. Frost protection overnight at those temps, soaked hessian if a warm summer.


Expedition Leader
IF you are building from scratch I'd put some nice large footings under the rack pillars, just to be sure. At $5-7cu' they're cheap insurance. At least 2'x2' and twice as thick as your slab. Talking an additional $20-30 worth of concrete. Total. Do more than the 'minimum'.
They dug out for my foundation on Monday and it passed inspection today.

Hoping to pour Friday or backup is Tuesday.

20x10 footings with perimeter bars, fiber mesh, steel mesh. Its a 4000psi at a 6" depth and I am having them cure and seal it.

Eventually there will be a 30' x 22' garage on top of it with 10' walls and a 4/12 reverse gable roof that will put it about 14' tall. This is the max I can build where I live. Doing 3 single doors that hug the roof so I have maximum clearance inside for 4 post lifts if I choose to go that route, I have no plan to do a 2 post so not worried about any further concrete reinforcement. This is in addition to my 2 car attached garage because I like to work on stuff and my family has a car problem... I own 4 and a trailer and my Dad has one to store in the winter....