Two Post Lift

[Don Justham]

Need some help. I am building a workshop and want to install a two post lift. The foundation will be your typical 4" slab with I think 3000 psi concrete. What do I need to do in the area that the lift posts will be mounted? I am thinking that I will need to dig out a larger area and go deeper with it? Anybody have experience with size and depth? I am thinking that after that I will drill holes and insert anchors for the bolts. Thanks for the help.

[William O.]

Re: Two Post Lift

4 inch concrete is a little weak, ok for a driveway , If you can layout the posts for your contractor to pour footings at the location ... footings should be 2' x 2', it not alot of money to do it right.

Bill

[Dick W.]

Re: Two Post Lift

I just went to Rotary Lifts web site www.rotarylift.com and checked their recommendations on a 9,000# lift. 4 1/4" of 3,000 p.s.i. concrete and minimum of 3 1/4" of anchor embedment. I think that this is a pretty universal spec within the lift industry. I did 5" of 5,000 p.s.i. concrete for my floor and have had some very heavy vehicles on the lift 10,000# + with no problems

[William O.]

Re: Two Post Lift

The inserts are 3 1/2" does not give much for error, the labor for footing is inexpensive....I would pour the footing's, use steel mess and rebar.

The commerical pour is 6-8" they would never pour a 4" slab.

[John O.]

Re: Two Post Lift

Hi Don

I just saw on TV on a car show where they were talking about lifts. First of all on a TWO post lift, they recommended that you pour about a 2foot by 2foot by 2 foot deep concrete block to hold the load of the vehicle on the posts. The garage floor itself has nothing to do with the lift. Only the footer area. But also did you consider a four post lift. It does not need that thick footer and is safer. Just put on floor and go.Plus you can park a car under it. As they said on the show, you have to make sure the car is centered on a two post lift so you don't get wobbling. I'm considering buying a four post lift for myself.

Just my 2 cents............John

[Wayne P.]

Re: Two Post Lift

6" is what the instructions with mine said for the slab or footer. Thr four post is a pain for working. You still have to use a jack to do any wheel work. The four post are great for parking. Decide which is most important for you. I keep a car stored on my two post with NO problems.

[Dick W.]

Re: Two Post Lift

4"-5" of 3000 psi with #4 rebar on 18" centers is adequate for a home shop. I pour 6" of 5000 for commercial shops with no cracking.

Rotary has been building lifts since only 1925. Maybe they know what they are talking about in their specifications.

[William O.]

Re: Two Post Lift

We can debate on manufactures specifications, so called typical building codes, but for the dollars, pouring footers would be an inexpensive investment.

[Kent K.]

Re: Two Post Lift

Dicky is close even though he's had a lot of experience. I'd recommend "Factor of Safety" rules and pour a 6" thick pad, 30" x 30", with #5 rebars at 8" on center both ways under the center of each post for 2 post lifts. Those pads should be integral with a 4" thick concrete slab with #10x10 welded wire fabric pulled up to the center of the slab in thickness as is normal for slabs. Yeild strength of the concrete for home use could be 4,000 psi. CAUTION: do not use fiber reinforced concrete (FRC) unless you wish to shave it evry so often!!!

Best regards,
Kent #6201

[Mike McKown]

would one of you injuneer types care to calculate

exactly how much tension force is on the anchor bolts if a three thousand pound car is sitting one foot (even three) off center of gravity, six feet in the air. Don't forget you have about eight anchor bolts in the concrete. I'd bet one bolt would more than hold the load under the description I described. What do I know. Went to the eighth grade and dropped out.