We had to take out some concrete in an auto body shop that was not thick enough to support a automotive 2 post lift. We poured some new concrete at the proper thickness that was required by the manufacturer.
As a former distributor/installer of lifts there should have been a continuous pad poured from post to post 2 foot past post on each side and minimum 6 inches deep with pinning and 4000 lb or better concrete. The lifts should not be installed in less then 2 weeks after the pour. I have seen what happens if this is not followed installing overhead or non coupled 2 post lifts.
Now that sounds right. I recently watched another video where the guy was using eight inch long Sampson wedge anchors on a residential poured concrete floor. He was complaining that he has to keep tightening the anchors. He came to the conclusion that wedge anchors suck and was moving on to epoxy type anchors. His comment section was very entertaining.
Do you think just leaving the slab the way it was is better than cutting out squares which now makes a weak point? Unless your doing it the way you said I feel like leaving it how it was would've been stronger.
@@tanthony298 , both are dangerous. The commentator knows more about it than I do but when you consider the weight and the hight on two legs. The single pour is so the legs don’t move independently. Personally I would go at least a foot down and bell the hole for a wider footprint. That way the mass has to move a lot of earth to shift. Cutting the floor is easy , digging the footing is easy and concrete is relatively cheap Think about lifting a car you pulled the engine on and it has a full tank of gas. Then you start breaking nuts loose on an unbalanced load. If you’re lucky , you don’t get hurt , but you’re definitely going to break stuff.
Yeah, they just wasted their time doing what they did in this video. It's still dangerously inadequate! Should've cut out for one solid slab, and dug down AT LEAST 6 to 8 inches further, and dug out under the uncut part of the slab to make the new pour key in underneath it as well.
I had my garage poured 5” thick with fibers and wire mesh. The building is 30’x30’. I bolted my 2 post to it with wedge anchors. Been there for 10 years now with daily use. I periodically check the nuts to see if they have loosened up. They never have.
I was watching this video and then my neighbour came and we watched it together. He said that this video changed his life and touched his heart. I then went and rented a projector in a big field and all my villagers watched it and it changed their lives too. We all are so grateful. Thank you for this video!
I was there. It changed my life. Not to be a negative nelly but maybe next time an intermission or maybe a porta potty would be nice. Until then keep changing lives.
I did 4x4 1.5’ deep pads. Compacted 6” gravel with lime dust. I have 12” of concrete. I made a jig of the bolt pattern of the lifts base. Welded them to an 1” thick plate. Welded 4 rebar posts on bottom of plate and positioned in concrete, leveled and aligned with opposite side. One side has one mounting position and other side has 2.Mini Cooper width and F 150 width. I epoxied rebar into original concrete, 3 per side and welded them to the mounting tubes. Didn’t want the tubes moving. I used 5009 psi concrete. A week after concrete was poured I lopped off tubing to concrete level. Overkill ? I think not. I work on my stuff by myself. So no. It’s a lot of work!
Bendpak recommends 12" rebar reinforced concrete for a 2 post lift on 4x4 pads. we are doing the same thing here hopefully ready to install lift by april 10th.
@@dawna2619 I didn’t know that! Wow. What’s the chance of doing exactly what the recommended. I’m serious. I didn’t know. Can’t remember if I mentioned, I made two mounting positions on driver side. Mini Cooper width and pickup truck width.
Some people need to read the install manual. 4’x4’x6” @ 3,000psi is what the manual for Rotory SPO10 when the concrete isn’t at least 4 1/2” deep for the Hilti 3/4x5 1/2 anchors.
What?! I used to work at that shop...in that building! I was working there at this time. I left a few weeks after the lifts were installed. Small world man! Just came across your videos the other day. Didn't realize you were in this area. Also, excellent job.
Back when I installed my 2 post A frame lifts, I was told the concrete needed to be a minimum of 4" thick. My floor is roughly 6-8" thick and I havent had any problems in the last 10+ years they've been installed. I might add that my floor is just a floating slab on concrete. It's an old barn that was never intended to be used as a work shop. It was just meant to dry grain in the winter. Like I said, Ive had no problems. I'm sure this qill be perfectly fine, despite the arm chair engineers critiquing your work. I think you guys did a good job.
Huhn? Hate engineers? Six to eight inches is clearly greater than four. Hate mathematicians too? 🙄 Some folk are engineers; however, I seriously doubt any professional engineers (PE, licensed) would comment because of liability. I'm definitely not a civil engineer but had to take their weed-out class of statics.
We have installed 1,000s of lifts. This is NOT how to do it. Pad should be 15 feet, left to right wide and 5 feet front to back and least 6 inches thick of 4000 PSI. It should CURE 30 days before installing the lift. Pinning to the sides is a good idea, but the wire mesh is a bad idea. Now we don't know much but we have been doing this since 1987.
I honestly think keeping an original slab all in one piece that's 4" or so thick with wire and rebar is stronger than cutting out a square and just to make it 5-6" and now you have a square that isn't bonded as good as the original slab I could be wrong but it seems right.
You are partially correct. However , the thickness affect the ability of the bolts to grab and hold. These will give way before the concrete crumbles are cracks.
yeah great job on the cuts and rebar, but since they're there, i would've unbolted that 1 column and just had them do all 4. have serious doubts that one column already anchored is better than what these guys are doing. sure it cost more, but so what pay them (they're worth it).
Hardly even went any deeper. 🤣 Coulda took out everything in between and given it some more heft. With the short load anyways may as well get the extra concrete and put it to work.
I found this same issue in my shop (existing when we bought the house, built in 70s) when I went to install a lift. I reached out to a buddy who is a mechanical engineer for a civil engineering firm who build bridges and suspended concrete including post tension pre-fab. My slab got cut in a 3 ft wide path in the shape of an "H" with lift posts at the intersections. Original slab was 4.5-5." thick but light on rebar/mesh, unknown PSI rating. Dug down to 18", compacted virgin dirt, then 3" road base compacted then 3" sand. Rebar cages at the post bases but outside the bolt radius and below 7" bolt depth, #5 rebar throughout, doweled and epoxied into original slab and 8" undercut under the original across the middle between the posts with same depth and prep as mentioned before. 5K psi with fiber, original slab prepped with bonding agent. Used misters on a hose time to keep it moist as it dried for 29 days. 7" Simpson wedge anchors for the 12K lift with 3/4 and 1 ton diesel trucks on it regularly and not a single stress crack 3 years later. If I'm going to climb under it, I know I can trust the work I did.
For the most part, this is an excellent retrofit, which may be considered overkill. However, there is one error in the procedure which should not be copied. Do not place sand over rock. With time, the sand will filter down, creating voids. This does take time and will be assisted by high water table. Google for more info.
the road base was called for because of the clay content of the virgin soil following compaction test. We used a 35% calcium chloride additive when compacting to ensure uniform surface with minimal porosity to prevent what you’re referring to. The. Vapor barrier of 6mil went down to prevent the sifting you’re referring to. Sand on the other hand is instantly compacted once it is wet so a layer of sand is ideal under slabs. Excellent point about sifting with sand over rock- I didn’t include this detail on my initial post as it was already long winded
Improper lifting and concrete prep causes the majority of issues, not concrete thickness. I've never had more than 4" of concrete. All my lifts are currently 12k 2 post, 4" concrete w/rebar. It's when people lift off center that causes a lot of stress on the anchor bolts. I've seen people lifting things that no way I'd walk under because of how lopsided the weight is. Company lift specs over the years keep increasing concrete thickness. It isn't because it can't handle it. It's issues with how it's poured, mixing, curing issues, and improper lifting that has caused manufacturers to suggest thicker concrete. If they tell you to put thicker concrete, it's to eliminate liability for them even though it's the users/installers/concrete layers fault. Specs are changing for the idiots were are today instead of people with common sense.
I installed the original concrete and it was done correctly and plenty strong enough for lifts even though when I built this building it was going to be a storage building to store cars that where partially taken apart. When the lift installer drilled for anchors they probably broke out concrete at the bottom of the hole so they wanted thicker concrete for the bolts. Truth be told I bet the floor was stronger before these squares where cut out and replaced
@@nalgas5569 I’m not well versed in the scientific aspect so don’t take this as gospel-wetting it slows the chemical reaction that takes place helps create the bond between the old and new. If it’s dry the old concrete will suck the moisture out of the new concrete at the point of contact too quickly, reducing the reaction and bonding. Or,,,,,,,maybe I’m full of💩
From an engineering perspective, that could have been done by welding a larger steel plate to the base and increasing the number of bolts using the 4 inch concrete. Would have been a lot less work. Would have to know the lift capacity to know what would suffice, but doubling the base footprint would be more than enough.
I have a question about the rebar tie in to the old concrete. You just drill a hole and stick it in? No epoxy or anything to hold it and fill up the extra space in the hole? Thanks for sharing.
Sir, please do a little PSA work. Lots of your commenters need names and addresses so the Manufacturers can learn how to properly install their products. APPARENTLY the Manufacturers are clueless! 😮 ...how do you put up with that??@bondobuilt386
I doubt it was OEM recomendation. I suspect this install was by lift provider company practices. Y'know their motive is way different than an engineers motive working for the manufacturer. Sell lift installs, get by with minimums, go banko when sued.
Please, for the love of god, NOBODY should be using this video as a guide of how to properly support a two post lift! They just wasted their time doing what they did in this video. It's still DANGEROUSLY inadequate! Should've cut out for one solid slab, and dug down AT LEAST 6 to 8 inches further, and dug out a little ways underneath the uncut part of the old slab to make the new pour key in underneath it as well, and use proper thick rebar throughout the entire new pour.
This is what the lift manufacturer and lift installer asked for I did not engineer this they did. 4-1/2" is all they needed but this area was only 4". My new pads are 8" thick in the middle and 5-1/2" on the edges. There not going anywhere.
Exactly. They are talking as if the vertical load is the issue. It is not. 4” concrete will hold all the load that lift can generate. The issue is the torque generated with asymmetrical loading that always occurs. With that in mind, the patchwork concrete was probably worse than the original.
That job looks sketchy as hell. I think you guys missed the point here. It’s 5” minimum on a monolithic slab. Those cut-outs and new joints now actually make it weaker than had you left it as it was 🤦🏽
We just did what the lift manufacturer asked us to do. The new pads were thicker than they even wanted. I had them over 8" in the center and about 6 around the edge.
I have a two post lift for personal use rated for 8700 lbs max on 5.5 inch thick rebar renenforced 5000 psi concrete on a monolithic slab. I always put Harbor Freight safety jacks on all 4 corners of the vehicle, they are supposedly rated at 4,000 lbs each, once the vehicle is in the air. They also keep the vehicle from rocking. Then again, I'm not in the business so the time spent placing the stands each time isn't important to me.
we did a 4x4 foot square pad when we did my buddy shop and it was 12-14 inches deep. we beat bars under the other concrete in all direction and made out little wire mess .. the guy that did the install said it was to much over kill.... i said u only live once and why did because of $50 or $100 extra concrete.. and for some of u who dont know.. ask how much is a yard of concrete... xxxxx plus delivery charge for such a small amount... or if u ordered say 3 yards then no delivery or it was cheaper.. so why not dig it deeper or bigger vs paying delivery charge and having just 5,6,7, inches of mud vs a good foot or more.. unless your wife has a great life insurance policy on you then she might only want it 2 inch thick... haha.. but its worth asking XXXX yards with no fee vs delivery fees.
My 3rd try to watch. The video jumps to a different one about half way. Had another one that it looked like RU-vid actually spliced with another video. When I noticed it changed I went back and found the one I was watching and fast forward to where I was and it was the other video.
Rebar should’ve been thicker two levels up and lower + deeper + should’ve used some commercial cement glue between old and new concrete + use a vibrator to remove air from concrete + wet the area where the concrete will be poured before using the concrete glue
Take a post hole digger and dig at all four corners run rebar down the holes tie the rebar to the slab rebar this will stabilize the pad, rebar gives the concrete its strength
I ask because I don't know. Is that rebar adding strength to the footings? The rebar will only be anchored on one end in the new concrete. The other end will slip in tension won't it?
Come on dude? why would we go through all that work to take out 4" and not dig it deeper. It was 8" in the middle 6" on the edges. Your comment is appreciated though because it helps the channel.
my concrete is super sketchy so changed up from a 2 Post to a 4 Post. even if my concrete were great, the 4 Post was still likely the best choice (in my situation) given the space limitations.
Way to small squares that will lift up in the future.. A 15 by 15 poured pad would have been a lot stronger.. So you just cut 6 by 6 squares and still the same thickness as the original floor. You need to go deeper at least 12 iches and pin it to the sides.Also need to wait min 30 days for concrete to cure. Bolts are another issue I would only use L type buried in the concrete
Made a special point of raising the rebar on the first hole - BUT DIDN'T ON ANY OF THE OTHER HOLES. - Keep this video for the Insurance claim when it fails.
Umm, I have installed lifts in the past. It seems to me that the insert pads are creating a weak spot, not making it stronger. it seems an engineer was NOT consulted. I would insist on an engineering report before allowing the first saw to touch concrete. EDIT i am saying monolithic pour, with heavier rebar for entire pad encompassing both lift upright anchor points. Also, using 3000 PSI or better concrete.
We had our floor poured deeper under the lift legs... but never bought a lift. 🤷 Someday someone will wonder why that blue tape is stuck to the floor in the barn. Oh well!
Many years in the construction biz- [Sorry guys the install is not good] Concrete too shallow - Steel too thin Instead of all that effort, You can just use a 2ft square of half inch steel plate tapered at the edges no mods required, cheaper and better and removable
Most concrete pours are not safety critical in that they just need to support weight in compression. In this application, if there is heavy truck up, perhaps exceeding the lift rating (like the mechanics will check the GVWR), there could be torque forces on the "pier" transferred to the rebar into the other slab. How much effort and time would there be to add epoxy to the rebar just to make sure your customer doesn't have a fatal accident? To me, the difference between going the extra mile and the small details that matter. No end product shown either. More small details that don't matter here. "Not needed in this situation".
We were hired to pour the pads at 6" thick and we poured it 8" instead. We also upped the PSI of the mix and added plasticizers and accelerant to make the mix stronger and cure faster. The pads are on super compacted stone. The rebar dowels were not even required but I added them on my own. Please keep telling me I did not go the extra mile. LOL@@LisaMedeiros-tr2lz
The failure mode for these lifts is concrete breakout on the outer anchors. The center of rotation (or moment) it the inside baseplate edge. Any concrete further than about 12" from the anchors has no effect on the failure mode. When tied to the existing slab with rebar you are not going to "rotate the entire new slab out of the hole". The two keys here, assuming 3/4" anchors is that the concrete is thick enough to let the wedge anchor "set" effectively. As long as you have about 3-4" below the bottom of the drilled hole the anchor does not "see" anything deeper. There is a great piece of FREE software at the Simpson anchor site called "Simpson Strong Tie Anchor Designer" where you can enter ALL of the variables from anchor model, concrete strength and thickness, baseplate layout, Moments and forces, etc. Food for thought...
Bondo nothing like self levelling concrete! When I built grain elevators, we poured a slump of 1 or 2, and depending on the temp outside , we used accelerate of 3% to 5%, and even hot water. This was slipform and we average 20 to 25 feet per shift on average.
You are describing RCC concrete. It is generally compressed w/ heavy machinery. There is some usage in dam construction today but that is irrelevant. We have poured tall foundation walls for Four story commercial masonry buildings w/ a 4" slump w/ the blessing from the on site quality control lab technician & the licensed supervising civil engineer.
@@billupstateny9151 yes, on the grain silos , we vibrated the concrete in place , and if we poured a 4 slump , we have fall out because it would not be set up enough when jacking on 2 or 3, and from the top of the deck to the bottom of the form, we only had 39 inches, and we got caught many times in a thunderstorm, and the pour went on nonstop. From the moment the pour started until it ended, we poured continuously until the towers reached full height and the deck was pinned. We has 50 ton and 20 ton jacks all around the deck, and the 50 ton jacks was near the steal steel roof beams that we transported up with us and the 20 ton jacks was in between with verticals rebar between the jacks every 12 inches. The tanks was 40 ft Dia to 80 ft Dia and the height of the silos was 160 to 180ft a 6 pack was 40ft dia bins 160 ft tall, and if it was a drive through with a dump pit and head house, the head house was a second slip that took the tower over the head house an additional 40 ft. If concrete after the roof pour. We poured concrete when the temp was 20 F degrees Self leveling concrete was forbidden on these jobs, and we had an inspector on the job who took,a sample from every truck and measured the slump before it was poured, and times the truck was rejected and they would dump in the rejection pit the load of contract. I guess when you have a million bushels of grain plus, the concrete has to be strong as possible. The base slab was 4 ft thick and full of steel, and while the tower was going up, that base slab would sink in the ground 9 to 12 inches and when the complex was full of grain, it sink another 12 inches, and below the base slab was Man ways which had conveyors stalled for moving the grain out of the tanks and those wall was 24 inches thick. Back when I was 19 years old in 1982 when I worked on building grain silos for government grain, it is a job one never forgets, and I look back and wonder how I ever did that type of work, being afraid of heights like I was at the time.
You definitely wanna run one big pad post to post. Not two squares. I only know that because my concrete guy made me add to my materials when I installed mine. That said my buddy has his old lift in two blocks and it’s fine?
At 2:10 the "wire mesh" looks like fence wire, doesn't look like regular wire mesh. See how easy it bends when being pulled out... Not a good original slab.
The forces on the rebar under a heavy load on the lifts would be bending and shear, they are not under tension, epoxy isn't going to do nothing whatsoever for that install.
The concrete needs to be thicker since an anchor bolt needs at least 1" of concrete under the end of the bolt to avoid concrete blowing out. If your lifting light loads you may get away with thinner concrete but many lifts need an anchor embed of 7", plus the 1" for 8" total. Or you can design an extended baseplate that spreads the load, allows more anchors but shorter anchors. Need a engineering design for the baseplate with appropriate calculations.
As an engineer, I will say I certainly would NOT rubber stamp that design! I'm wondering if this was a "dealer" that gave foundation specs. A dealer has no structural competence, and there should be something substantial from the OEM. For clarity, the "psi rating" or compressive strength of concrete is NOT the issue here! Concrete almost never fails in compression. Those tall posts become moment arms driving forces into that concrete.
@@bondobuilt386 That is an impossible answer without more details but I am not trying to throw you under a bus. You may have done as instructed, nothing more. Reality is a small pad like that will want to rotate with asymmetric loading, which will always happen with a vehicle, and that force will load only as upward sheer in those pins. My first gut reaction is more of a "pier" design to help react the loads, but again not involved. People lose their mind with depth like we are only trying to "support the load" in bearing. Not the case. When you go deeper, you are now reacting in the soil. Remember this, concrete has very high 'compression' strength, but only about 1/10th in tension so 4000psi concrete can fail at only 400lbs in tension. This is why steel is commonly used in crete as them compliment each other and steel is a tension king. It also blows people's minds to know that rebar does nothing in a thin slab until the crete breaks. Thus the massive difference in pre/post tensioning.
Nobody wants to get their hands dirty! Instead of a rake get in there by hand and make sure the concrete gets into every nook and cranny especially under the rebar then use rake for finishing especially on a weak gameplan like this one !
My ONLY concern on this would be EVs. They weigh twice what ICE cars do. The Last time I saw this done in a shop they did 5'x5' and a foot deep with rebar. This should be fun.
Saw a distributor mention parameters It should be 4000 psi with #5 rebar at 12" oc The cutout should be 6x6 and be no less than 8 inches deep. 6 inches is not enough like the distributor said You need at least 6 mil vapor barrier Should of checked how the compaction was below as well 28 days at least curing time. Not two weeks unless they pay for hot concrete with a 7 and 14 day break from a geotech to be at least 90% of required psi of 4000 Should of used slab bolsters to get the rebar off the ground and never use wire mesh. He definitely got what they paid for. Cheap isn't quality and quality isn't cheap
Next time just use CTS Cement, Rapid Set Concrete Mix, Very Rapid Hardening Concrete, non shrinking, from 2" to 24" , 1 hr. 3,ooo PSI compression strength, 24 hrs. 4,500 PSI, 7 days 5,500 PSI and 28 days 6,000 PSI.
