2 post lift ,concrete,expansion joint

[69crewcab]

Ok group had a slab poured 24x24 and have a 10k asymmetrical lift to install
Only thing is where they put the joint for cracking is right where a post needs to go.
Now i over did it and poured it 8” thick and fibermesh reinforced concrete. Do I need to worry about the post being over the joint? Joint only goes down 1/2 inch in the concrete

 

[65ranchero]

When I had my 7K 2 post Mohawk lift installed the lift had to be moved so slightly so the base of one post would not sit on the exp. joint
4+" whole floor and the joint is maybe 3/8"
But in reality I don't see why not, the base may have to be shimmed anyway and non shrink grout to help keep it level.
Plus the base will spread the load.

 

[purediesel]

Read the installation manual closely. Most require to stay at least 6" away from a crack. The joints are put in place for a controlled crack so it will more than likely crack in the joint. Control joints are a good thought to have about before lift placement. If you don't have heated floors then just move the lift.

 

[infinkc]

The problem is the joint is designed to allow the concrete crack there instead of the slab. When the post is down, how close are where the bolts will be to the crack? ***** that you didn’t tell the concrete guys not to put a joint in the general area.

 

[ConCretin]

A 1/2" deep cut in an 8" slab is unlikely to result in an induced crack. Control joints should be 25% of the slab depth. With fiber mesh in a 24 x 24 slab you might not even see a shrinkage crack at all. You are probably fine.

 

[Chris705]

Consider using an anchor bolt that gets epoxied into the slab……

 

[firebirdparts]

I’m not convinced the 8” concrete will actually crack where you tell it to anyway. That saw cut is relatively not a strong influence.

 

[wssix99]

You should follow the instructions for the lift, which tell you to set the post a certain distance away from the cracks or control joints.

Crack, or not, that control joint is now a weak point in the slab where tensile stresses (from shrinkage) are concentrated more than other parts of the slab.

The anchor bolts bite into the slab and create stresses in the concrete in the shape of an upside down cone with the tip of the embedded bolt, radiating out to areas beyond the baseplate of the lift. If the control joint intersects these cones, then the anchoring of the lift is weakened.

In order to get your full safety factor intended for your lift, you need to either:
- Move your lift location.
- Tear out and redo the slab.
- Switch over to a 4 post lift. (Bolting is typically optional for these, so not saftey-critical.)

 

[charbar]

My two post has on column that sits right on top of an expansion joint and the other column is probably 4 inches away from one. 5.5 inch concrete, can't remember how deep I made the cuts-1.25 inches maybe?

Been that way for years now with a bajillion vehicles on it, lots of them being crew cab long box dually diesel pickups-Ive never had a problem.

 

[like2wheel]

Not mine, but this 2 post lift was professionally installed several years ago, and used daily ever since. The other leg is also over the same horizontal cut.

Not saying it’s right, but I’ve seen several others similar. I even know of one that was installed over an actual expansion joint tar strip.

 

[wssix99]

Not mine, but this 2 post lift was professionally installed several years ago, and used daily ever since. The other leg is also over the same horizontal cut.

Not saying it’s right, but I’ve seen several others similar. I even know of one that was installed over an actual expansion joint tar strip.

By the look of the floor, I assume that picture was from a professional shop. If so, it's a shame people would put employees at risk like that to make a buck.

The OP is talking about installing a lift on a single joint, which would reduce the ultimate strength of some of the bolts. In the picture above, there are two joints and one repaired hole. Not a single bolt on that lift would have its intended strength.