What's new
By:
Filters

Two post lift installation in shop

reklund5

Red Skull Member
Joined
May 22, 2020
Member Number
1165
Messages
62
Loc
Northern Nevada
So I finally have a house with a shop, and finally got my 100A panel hooked up in the shop. Its time for a 2 post lift. Most I see that are under 12k capacity say that you can get away with a 4" slab...which is what I have. Anybody have experience installing a 2 post lift and can provide some feedback? I was thinking I'd have to cut a section out and put in some rebar and a 8-10" slab where the posts are. If I can just stand up the posts and put in some anchors in the existing concrete that'd be sweet...but I don't want to have it all tip over with a truck in the air.

I'm really familiar with using lifts as I was a professional tech for years at a Toyota Dealership. I know about properly loading and balancing a vehicle and all that. I just don't know concrete and how much force I can put on the existing slab.

Educate me. I've been waiting 20 years for a lift of my own in a shop of my own.
 
I've got a 10k Atlas 2 post in my shop. We poured the slab a little thicker ok that side where the posts are. Believe it was around 8" in that area. Also didn't saw cut that side. Regularly put my CCSB Duramax and a friend's CCLB dually Duramax on it without issues. I do use stands underneath with them once in the air though.

If you do cut out and pour deeper, make sure you tie it into the existing slab well.
 
I have a 2 post Atlas lift. The bolts that came with mine became loose pretty fast. I swapped them out for some Hilti anchors and so far they've been good. Lifts are designed with relatively low factors of safety, after my first bolts had issue (which I've been skeptical of lifts from the get go) I analyzed the loads on the lift and anchors and then even talked to the guys at the American lift association of whatever it's called. My point being with all this, in retrospect I would've gotten an overhead lift (mine routes everything below, which seems nice but having an overhead brace would make a huge difference if anchors begin to fail) and I would get a lift designed way higher than what you want, since frankly they're not designed with much overkill in the first place. Mine is rated to 9000lbs, I analyzed the anchors would rip out at like 20000lbs, but that's assuming all the anchors are fully engaged and working and the concrete is what you think and behaving perfectly and there's no weird loading, etc, etc. Since adding the Hilti anchors I've had my Tundra up in the air (only like 5500-6000lbs) and the bolts didn't show any signs of losing torque, but personally I'd never go near the 9000lb rating. Do it over again, overhead 2 post rated to 12k and swap any shit they provide with Hiltis.

My slab is 4", but you have to get considerably thicker to get a substantial increase from the anchors. I used the mechanical expanding anchors, a lot of people online suggest epoxy anchors but the epoxy is rated lower than the mechanical anchor if you actually read the Hilti spec sheet. I also drilled all the way through the slab which was the only way I could get the original anchors out when I swapped them, I would definitely suggest doing that.
 
Add bigger base plates (and gussets) if you're worried about it. The base plates they come with are so small it doesn't take that much plate to cut the pulling force on the anchors in half.
 
I've had friends tell me not to use rebar under the lift - they tell me that it can interfere with the anchors getting installed. I don't think I'd feel safe with a 4 inch slab hold the the lift. Putting in dedicated footers (30x30, 24 inch deep tied into slab) might be safer.
 
arse_sidewards said:
Add bigger base plates (and gussets) if you're worried about it. The base plates they come with are so small it doesn't take that much plate to cut the pulling force on the anchors in half.
Click to expand...

If you're worried I would do this. Is the lift one with the top bar across the posts? If so all your loading will pretty much be straight down if you have the vehicle balanced properly on the lift.
 
Thanks for the feedback. I'll be getting a 2 post with the overhead brace for sure. I was also planning on swapping out the chineseium anchors for some of the good Hilti or equivalents. I'll see if I can get some photos of the slab and where the lift will go and see what you guys think. There is one small crack in the existing concrete, but I don't know if it'll affect where the lift goes. I'll definitely keep it away from expansion joints as well.
 
I work underneath two 12k 2 post lifts all day everyday. One is a Forward, One is a Challenger. The Challenger has bigger base plates, but I've never had problems with either of them and I regularly lift 4 door long bed dually trucks and people movers. Both lifts installed by me, on a 4" slab. I think you are worrying too much.
 
Mouse said:
I've had friends tell me not to use rebar under the lift - they tell me that it can interfere with the anchors getting installed. I don't think I'd feel safe with a 4 inch slab hold the the lift. Putting in dedicated footers (30x30, 24 inch deep tied into slab) might be safer.
Click to expand...

they are not your friends. thats not safer, at all.

there is only one gaurentee all concrete guys give... it will crack. and guess what, cracking is almost always, in large part, caused by inconsistent thickness. a stupid big footer is no good with outrebar to hold it tho the rest of the slab. and no rebar is flat retarded. i've never seen a lift failure from a decent 6" concrete slab.

most lift failures are because people spend the extra cash on dumb concrete work when it would be much better spent on a better quality lift. cheap lifts are cheap and mfg mounting reqs should be figured at a 4-8x safety factor. so dont go overthinking the rete
 
tracyb said:
there is only one gaurentee all concrete guys give... it will crack. and guess what, cracking is almost always, in large part, caused by inconsistent thickness. a stupid big footer is no good with outrebar to hold it tho the rest of the slab. and no rebar is flat retarded. i've never seen a lift failure from a decent 6" concrete slab.
Click to expand...


If slabs are cracking where you are then the base compaction was questionable regardless of how consistent the slab thickness is (or the slab is just fucking massive, you can't expect a 100x100 to not move a little somewhere). Something has to move for concrete to crack.


Rebar should be questioned for slabs that are exposed to a lot of salt. Sure it makes the slab stronger but when it rusts it breaks the slab. You have to consider whether you actually need the strength and how long you expect the rebar to last. Slabs without rebar have their place.

Footers should generally not be tied into the floor slab. Tying a footer that goes below the frost into a slab that does not is a great way to have the slab move and/or crack the footer over time. Even if you don't have frost seasonal changes in moisture content will do the same but more slowly.

x2 on "just follow the instructions" though.
 
Last edited:
We didn't put any rebar in our shop floor or the slab outside. 6" thick and fiber reinforced. Solid road base underneath the slab. Concrete is pretty much exactly 6" throughout because I set the forms and built a drag to show me any high spots which I then shoveled down and filled any low spots. We have one crack that showed up in an outside slab that wasn't in a saw cut. Another in a place where there was an internal corner not far from the edge of the slab. I should have expected that one to happen. Wish I would have saw cut it though to dictate exactly where it cracked...
 
arse_sidewards said:
If slabs are cracking where you are then the base compaction was questionable regardless of how consistent the slab thickness is (or the slab is just fucking massive, you can't expect a 100x100 to not move a little somewhere). Something has to move for concrete to crack.


Rebar should be questioned for slabs that are exposed to a lot of salt. Sure it makes the slab stronger but when it rusts it breaks the slab. You have to consider whether you actually need the strength and how long you expect the rebar to last. Slabs without rebar have their place.

Footers should generally not be tied into the floor slab. Tying a footer that goes below the frost into a slab that does not is a great way to have the slab move and/or crack the footer over time. Even if you don't have frost seasonal changes in moisture content will do the same but more slowly.

x2 on "just follow the instructions" though.
Click to expand...

well guess i learned something. i've been in construction since i could swing a hammer, and the only time i've ever heard of someone pouring a slab with out rebar or at least wire mesh is with fiber additive. i hate fuzzy concrete with the fiber, but thats also probably different place to place and by fininsh.

the footer to floor slab not tied together absolutely... although thinking about it the last time i was surprised how other places build/ pour concrete was people doing monolithic sp? slabs where the footer and slab are done all in the same pour.

and i should have clairified, by footer tied to the slab i meant the person who i quoted's thought of a thicker area where the lifts pads where to land.

i've got a 60x100 slab infront of my shop in 20x20 squares with expansion joints and every single one has a crack. the driveway is probably 160' with expansion joints every 20' and most have a crack in them. the shop is 4500sq ft smooth, 6" thick, saw cut all has a crack. nothing is terribly bad and the concrete has been down for 25yrs. but without the rebar everything here seperates and then gets worse with nothing holding it together. my concrete has held up much better than most the same age around here.


had to look up where your location is... yup complete opposite sides o the country i'm about as far upper left as it gets PNW

thanks for checking the 'learn somthing' box off my list today:beer:
 
Last edited:
So what about fiber reinforced concrete? Currently planning a 10k bendpak lift on a 6" fiber reinforced 3,000 psi slab.
 
tracyb said:
well guess i learned something. i've been in construction since i could swing a hammer, and the only time i've ever heard of someone pouring a slab with out rebar or at least wire mesh is with fiber additive. i hate fuzzy concrete with the fiber, but thats also probably different place to place and by fininsh.

the footer to floor slab not tied together absolutely... although thinking about it the last time i was surprised how other places build/ pour concrete was people doing monolithic sp? slabs where the footer and slab are done all in the same pour.

and i should have clairified, by footer tied to the slab i meant the person who i quoted's thought of a thicker area where the lifts pads where to land.

i've got a 60x100 slab infront of my shop in 20x20 squares with expansion joints and every single one has a crack. the driveway is probably 160' with expansion joints every 20' and most have a crack in them. the shop is 4500sq ft smooth, 6" thick, saw cut all has a crack. nothing is terribly bad and the concrete has been down for 25yrs. but without the rebar everything here seperates and then gets worse with nothing holding it together. my concrete has held up much better than most the same age around here.


had to look up where your location is... yup complete opposite sides o the country i'm about as far upper left as it gets PNW

thanks for checking the 'learn somthing' box off my list today:beer:
Click to expand...

I don't know if what he says is true. I'm working on a bridge near the coast. I assure you it has tons of rebar in it. They do take great car to assure that no rebar is exposed obviously.

Not that a bridge is the same as a slab, but I don't see how the rebar could rust when it's sealed in the concrete. I just demo'd a section of a bridge built in 1952 and rebar looked brand new.
 
YotaAtieToo said:
I don't know if what he says is true. I'm working on a bridge near the coast. I assure you it has tons of rebar in it. They do take great car to assure that no rebar is exposed obviously.

Not that a bridge is the same as a slab, but I don't see how the rebar could rust when it's sealed in the concrete. I just demo'd a section of a bridge built in 1952 and rebar looked brand new.
Click to expand...

Concrete is somewhat porous. Salt eventually gets in and promotes corrosion. For a structure that has to bear weight unsupported and has a defined lifetime it makes sense to do rebar. It is practically impossible to do a bridge without rebar since concrete is so weak in tension. For a slab that just spreads weight that the ground bears and doesn't have unsupported spans and you want it to last as long as possible it rarely makes sense to do rebar. You can put off the inevitable by using coated (or galvanized) rebar and if you're in a dry climate it will likely last hundred of years but eventually it will rust and start breaking the concrete. Google "epoxy coated rebar" if you want to read about it in detail. It was a big deal a few years ago.
 
arse_sidewards said:
Concrete is somewhat porous. Salt eventually gets in and promotes corrosion. For a structure that has to bear weight unsupported and has a defined lifetime it makes sense to do rebar. It is practically impossible to do a bridge without rebar since concrete is so weak in tension. For a slab that just spreads weight that the ground bears and doesn't have unsupported spans and you want it to last as long as possible it rarely makes sense to do rebar. You can put off the inevitable by using coated (or galvanized) rebar and if you're in a dry climate it will likely last hundred of years but eventually it will rust and start breaking the concrete. Google "epoxy coated rebar" if you want to read about it in detail. It was a big deal a few years ago.
Click to expand...

Like I said, I partially demo'd 3 bridges that were built in 1952 and the rebar looked brand new. I did leave out that they're in the middle of rice fields and see lots of humidity.

Salt may be a different animal, but I figure if it looks exactly the same as the new shit after 70 years, it's probably not going to rust. Especially in a shop slab.
 
Modern concrete cracks at 10 foot. I am not smart enough to tell you why. It does. Posts in the slab should have a diamond sharp, so the crack follows the point of the diamond. thicker is better. Modern fiber does not have hair. If hair type is used it can be "burned" off by the trowel machine. Thicker is ALWAYS better. A six inch slump is better than a three inch slump as far as strength is concerned.
 
Last edited:
crisbee1 said:
So what about fiber reinforced concrete? Currently planning a 10k bendpak lift on a 6" fiber reinforced 3,000 psi slab.
Click to expand...

3,000psi is not enough for a lot of lifts. I think 3,500psi is a more common lowest psi rating.
 
From Bendpaks website...
Pre-Existing Minimum Floor Requirements:
TWO‐POST MODELSMIN. THICKNESSMIN. COMP. STRENGTHREINFORCEMENTREBAR SPACING
GP‐7 SERIES MODELS4‐1/​4"3000 PSI / 28 Day Aging#6 Rebar12 in
XPR‐9 SERIES MODELS4‐1/​4"3000 PSI / 28 Day Aging#6 Rebar12 in
XPR‐10 SERIES MODELS4‐1/​4"3000 PSI / 28 Day Aging#6 Rebar12 in
XPR‐12 SERIES MODELS6 1/2"3000 PSI / 28 Day Aging#6 Rebar10 in
XPR‐15 SERIES MODELS8"3000 PSI / 28 Day Aging#6 Rebar10 in
XPR‐18 SERIES MODELS8"3000 PSI / 28 Day Aging#6 Rebar10 in
 
YotaAtieToo said:
I don't know if what he says is true. I'm working on a bridge near the coast. I assure you it has tons of rebar in it. They do take great car to assure that no rebar is exposed obviously.

Not that a bridge is the same as a slab, but I don't see how the rebar could rust when it's sealed in the concrete. I just demo'd a section of a bridge built in 1952 and rebar looked brand new.
Click to expand...

arse_sidewards said:
Concrete is somewhat porous. Salt eventually gets in and promotes corrosion. For a structure that has to bear weight unsupported and has a defined lifetime it makes sense to do rebar. It is practically impossible to do a bridge without rebar since concrete is so weak in tension. For a slab that just spreads weight that the ground bears and doesn't have unsupported spans and you want it to last as long as possible it rarely makes sense to do rebar. You can put off the inevitable by using coated (or galvanized) rebar and if you're in a dry climate it will likely last hundred of years but eventually it will rust and start breaking the concrete. Google "epoxy coated rebar" if you want to read about it in detail. It was a big deal a few years ago.
Click to expand...


Pretty much anywhere that may see salt exposure uses epoxy coated rebar in the bridge decks. Inland NC, where we only get ice/snow a couple times a year only does the decks and the the substructure is black bar. On the coastal bridges, I believe they're using more epoxy. Up north where there's consistent salt exposure they'll do just about everything coated. I've even seen some places call for stainless bar. I worked on a port wharf project many years ago that had a ridiculous amount of calcium nitrate inhibitor (CNI) in it, among about a half a dozen other ad mixes. Our batch plant had a mini chemical storage facility next to it to hold all the chem tanks. The design relied 100% on the CNI to block corrosion, even on stuff directly exposed to salt water. The the reinforcing was black.

Most failures people are attributing to salt corrosion are really from ASR - alkali silica reactivity where the cement reacts with high alkali aggregates over many years. That same port project required us to do reactivity testing on every combination of cement, aggregate, sand and admix we used. That was also around the time of the big cement shortage and we were taking cement from anywhere we could get it. Every time we switched cement, it was another 30 days of testing before we could use it.
 
What prices are you paying for your 2 posts? I got a quote for $5600 for a 10k challenger. California. Is that the ballpark?
 
Caddman said:
What prices are you paying for your 2 posts? I got a quote for $5600 for a 10k challenger. California. Is that the ballpark?
Click to expand...

$2000 shipped from amazon. Have had plenty of 1 ton diesels on it, but it only gets used maybe once a week.

But its on a 4000psi 6" rebar slab with 18" beams.
 
While we're on the subject...

I know everyone love the Chinese 2-post lifts. Are the Chinese making in-ground lifts at comparably rock bottom prices yet?
 
Turns out my concrete was good to go. Thanks for all the input!

Got it set up on New Year's Day. Just gotta run some
power to it now. It says 20A 220v...10/2 romex should be sufficient, yes?

CA8D47B0-14B3-4D63-9AE7-D1DA95CB7243.jpeg
 
10/2 will be overkill, but wont hurt anything (unless it wont fit in your outlet if you have it plug in), 12/2 is good for 20 amps.

Aaron Z
 
reklund5 said:
Turns out my concrete was good to go. Thanks for all the input!

Got it set up on New Year's Day. Just gotta run some
power to it now. It says 20A 220v...10/2 romex should be sufficient, yes?
Click to expand...

Reminds me alot of my old shop back home. I used to refer to it as the "tunnel". :laughing:
 
Which lift did you buy? How did you anchor it in the concrete?
 
You must log in or register to reply here.
Top Back Refresh