Concrete Questions 40x60

[Golden40]

How thick does it need to be for a 2 post lift? Can I have the 40x60 poured all 4" except where the lift goes? What psi rating should it be? I want to do this project right the first time, but I don't think I need 6" thru the entire shop. Any suggestions on this issue would be greatly appreciated!!!

 

[PCW]

How thick does it need to be for a 2 post lift? Can I have the 40x60 poured all 4" except where the lift goes? What psi rating should it be? I want to do this project right the first time, but I don't think I need 6" thru the entire shop. Any suggestions on this issue would be greatly appreciated!!!

Most full size lift would like to see 6 ' and 3500PSI. You can do like a 4'x10'x12" strip of concrete where the towers will be placed, that's what I'm going to do when I build my shop. Pouring an entire foundation 6" will cost you a lot more $$$$.

PCW

 

[hilld]

Look at the specs for your desired lift, the min thickness is usually 4", but the rating of the PSI is different. For example, BendPak, specs 3000PSI at 4" for their 10k 2post hoist, while Mohawks specs 4000PSI at 4.5" for their 10k 2post hoist.

Derek

 

[tcianci]

While a thick floor is needed to properly hold any anchors associated with the lift, As was posted, 4-5 inches should be fine. No one seems to worry about parking a car or truck on a 4 inch slab but if it's a lift, everyone gets nervous. There isn't really much difference except the weight of the lift itself. The tires of your car probably spread the weight of the car over a smaller area of the floor than the lift base plates.

 

[Justanoldguy]

The tires of your car probably spread the weight of the car over a smaller area of the floor than the lift base plates.

Exactly.

I would just do a 1ft x 1ft x 1ft pad under each leg just to be sure with the hold down bolts.
That's like a half dozen more shovel fulls of concrete..

 

[brownbagg]

where ever you have a different in thickness, it where the concrete will crack so if you decide to place one section thicker, make sure its a bay or section and saw cut that section deep to control the cracking. so under the lift I would place at least 15 ' x 20' six inches

 

[Golden40]

Thanks for the info! There is alot to decide when a guy is building a shop (4 Life), I'm overwhelmed!! Oh well, it's a good problem to have.

 

[Justanoldguy]

at least 15 ' x 20'

15 ft x 20 ft seems excessive

 

[december45]

my 40 by 60 shop's floor is 5" and about 7 to 8" right where the posts bolt to the concrete, i think i made those areas about 3' by 6', two strips, i wasnt exactly sure about where the lift was going so i made it so i had some leeway when placing the posts.

 

[6768rogues]

My 2 post 9000 lb. lift required 4 inches of 3500# reinforced concrete. I put in 5 inches of 4000# with #4 bars every 2 feet in both directions and fiber mesh. I like to be an over achiever.

 

[brownbagg]

15 ft x 20 ft seems excessive

size of car bay, the lift needs to be away from any control crack, so 15 x 20 couple more inches is only two yard, that cheap for insurance

 

[Shocker]

So I just poured 6" of concrete for my woodshop addition. I paid $80 per yard for 6 sack, which I believe that is 4000psi.

So for your pour, $2400 for 4" and $3500 for 6". A bit of money to be sure, but not overwhelming IMHO.

I only bought 5 yards (minimum delivery) so you might be able to get a better deal on a 44.4 yard pour.

 

[balddave]

There isn't really much difference except the weight of the lift itself.

I definitely disagree here. There is a lot of difference when you raise the car 5-6 feet off the ground and start wrenching on it, you will be generating large moments (like torque) and these will result in tension of the concrete. Moments kill when it comes to qualifying materials. Additionally tension failure occurs much before compressive failure, for example for "6000psi" concrete tension failure can occur in the neighborhood of 700psi. When concrete is listed as 3000psi or 4000psi ect, that's only the compressive strength.

 

[brownbagg]

a subject no body talk about, anchor bolts, I know lifts are installed using those drilled exspansion bolt, but if I had the choice with new contruction, I think those hook anchor bolts embedded in concrete be better

 

[hilld]

a subject no body talk about, anchor bolts, I know lifts are installed using those drilled exspansion bolt, but if I had the choice with new contruction, I think those hook anchor bolts embedded in concrete be better

The problem with anchor bolts for lifts is that they would have to be in the exact location as the holes in the lift are already drilled and to make things more difficult, you would have to lift the lift high enough to clear the bolts for installation. Normally with J-bolts, if doing wood construction, they drill the hole in the sill plate after the fact so they have a little of a fudge factor. I agree J-Bolts would be safer but probably not very practical in reality.

Derek

 

[BoostedOne]

In the manufacturers minimum recommendations alot of them say 4", but thats because they found that its adequate(not ideal) and they know that most people have 4" slabs and many customers are not building the garage around their lift, however adding the lift to an existing slab.

My lift has a similar requirement as the others(4", 3500psi), howeveer the tech guy said if your doing a new pour, go 8" thick in a region 1 foot wider in each direction of the base plate, gently tapered to the 4". Doing the entire floor is over kill, or even the entire bay.