Concrete Thickness help

[BigBlue1]

I have been told that I need to have a 6" slab to put a 2 post lift in. Can I get away with a 4 inch slab? I am building a 40X50 shop. I know a 4 post takes up more room would 4 inch slab work in that instance? I have read muliple peoples post but come up with conflicting data. Any help would be appreciated

-Jason

 

[Sheepdogmarine]

Jason,

Hello. I had a 2 post lift on a 4" slab before. It worked out fine. It was in a shop I was renting. This is the minimum the lift manufacturer called for.

It was a 9000lb lift and had nice wide feet on it so it spread out the load well. I have seen some lifts that had much smaller feet.

On my current garage I am putting 6" where the lift goes just because.

Check with the lift manufacturer. They can tell you how thick the slab needs to be.

Just a hint and you may already know. Don't try to drill the holes with a regular drill and a masonry bit. Go rent a Hammer drill with a splined bit. It took me two hours and lots of cussing to drill the first two holes with a regular drill. It took 20 minutes to drill the rest after I rented a drill. Best $30 I ever spent.

Good Luck!

 

[6t7gto]

My 2 four post lifts are on 4" of concrete. No problems.
I have witnessed a 2 post get professionally installed on 4", also.
No problems.
david

 

[scarman]

I also have a two post lift. I poured 4inches except where the two post lift was going to be installed. I went 6 inches only in a 4 foot area for each lift pad. I knew exactly where my lift was going to be.

 

[Spaggs]

Mohawk recommends 4" minimum with 4000 psi concrete. If you haven't poured yet, I'd recommend more, since if you pour at 4", there is no guarantee that you will have a consistent 4" layer all the way across. I went way overboard with a minimum of 6" with 12" footers where the posts stand.

Good Luck to you.

Spaggs

 

[Kevin54]

You won't need a 6" slab over your complete floor, just dig a few inches deeper where you KNOW the lift will go. Just make sure you have a large enough footprint at a deeper depth to allow for error in placement.

 

[kyle242gt]

Quick question, and if this is a threadjack, tell me to go pound sand... but reading about drilling holes and new slab work brought something up in my tiny brain.

Is it better to pour the slab, then drill, or install the bolts before pouring?

 

[nate379]

Why not just pour a 6" slab?

Maybe it's because I have lived in places that have bad frost, but 6" 4000-5000psi is the norm. 4" slab perhaps for a small garden shed, but I don't think it would hold up that well for a workshop.

Granted you can have a 6" slab that is weaker than a 4" depending on the steel, base prep and psi mix.

 

[mcmaster68]

That's good to know that a post will work on a 4" slab. I didn't have the money to go 6" and didn't know where I was going to put a lift ahead of time.

 

[toxicz28]

Is it better to pour the slab, then drill, or install the bolts before pouring?

Not necessarily better, but easier. If you install the anchor bolts before the pour, your measurements and bolt locations need to be exact.

 

[porschedude996TT]

Something to consider is that when you talk to a concrete guy and say 4" that means 3-1/2" and when you say 6" that means 5-1/2" thick because they are using a 2 x 4 or a 2 x 6 in the frame of thinking. I'm not sure if the guys making the lifts are on the same page. It may be worth asking the question to both so that you are not on the light side of the pour. If you know where the lift or lifts are going to be, the cost to add steel and thicker concrete in that area is not very much up front. Just a thought...

 

[kyle242gt]

Not necessarily better, but easier. If you install the anchor bolts before the pour, your measurements and bolt locations need to be exact.

Thank you very much - back to lurking.

 

[walsher]

If you google lifts you will see that virtually all of them 2&4 post up to 12,000 lb call for
4"s of 3000 psi concrete. However more is always better and it will only take about 1/2 yard more to make the 12'x6' lift area 6" deep

 

[fclaridge]

Also when drilling concrete, I have found drilling a smaller pilot hole makes the big hole easier to drill. Correct me if I am wrong of if this is a bad way to do it, but it sure was a lot less strenuous and faster.