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So I just looked and Coats recommends a "MINIMUM"4 inch thick 3000PSI aged for 30 days. Bend Pack say 4 1/4 thickness and has specifications for rebar spacing as well...
ok, i'll pick a spot for the lift and tell them i need minimum 6" in that area. I know it will never be perfect all the way across. I've watched videos where people hammer out concrete to put a thicker area and the variance in thickness was pretty crazy. If i get a chance i'll drag my box blade across the area to get it as smooth as possible.
ok, i'll pick a spot for the lift and tell them i need minimum 6" in that area. I know it will never be perfect all the way across. I've watched videos where people hammer out concrete to put a thicker area and the variance in thickness was pretty crazy. If i get a chance i'll drag my box blade across the area to get it as smooth as possible.
Not sure if you picked a lift brand yet, but i would also double check with them. I am sure the specs will be similar but never hurts to double check.
Yeah the variances can be crazy depending on who did the work.
I spoke with one of my dad's friends who is not an engineer, but has erected several buildings himself over the years. Commercial and residential. He suggested spending a little more for:
6" thick slab Pretty overkill, yes. I would do a 5"
12x12 perimeter beam with 12x12 beam on the 30' center of the shop. That should be fine.
#4 rebar 16" on center instead of #3. 4 pieces of rebar in the perimeter beam and center beam (one in bottom, and one near top) That will work. The grade beams need at least 2 top bar and 2 bottom bars. That will serve to tie the stirrups (the loops).
1.5" x 1.5" sheet lip around perimeter of slab and a relief cut to prevent a potential crack from spreading across the entire slab. Yes, I see that lip on most metal buildings. The relief cuts are called control joints, and are usually sawn within the first 24 hours after pouring the lab, but the earlier the better.
he admitted to not having any experience with a two post lift and suggested a12x24 spot where the lift belongs. everything i see on two post supplier sites shows that that is way overkill. even with a suggest 3000 psi concrete where i'm getting 3500 psi.
Vehicle lifts are a can of worm if you ask me. I've never seen manufacturers publish forces, reactions or moments and the minimum slab recommendations and anchors seem on the light side. I would want to see something like 5-6" of anchor embedment for any connection that's critical. If you follow the building code for design, you will wind up needing 7-8" of thickness, just for the connection. Slab resistance or overturning is a separate check. By assuming nominal loads and eccentricities of what vehicle likely weighs on a 2 post lift, you can certainly make the numbers work on a slab minimum 4-5" thick, but increasing eccentricities due to some unintended or accidental loading the same numbers won't work by a huge margin. I wouldn't use minimums here and go with a very conservative design and use at least 8" with the anchor embedment I mentioned. I would personally do 12" thickness if I was building for myself, again doing something like 4' square. Overkill? Yes. Working under a 6,000 lb vehicle is extremely dangerous and you don't want anchors or a slab failing on you if somehow the vehicle gets bumped or jolted by accident.
Here's a screenshot of a common software used to design concrete anchors. I threw in some loads I would assume are close enough, but unknown to me is the eccentricity of loading. The program then calculates the anchor embedment based on loading, ranging from 2.375 to 3.125 for that specific adhesive and different anchors for a 6" slab. Does that work? Absolutely! Would I specify those anchor embedments in practice? Absolute not! I manually overrode the highlighted 6" embedment and got an message saying minimum concrete thickness is 7.25". Those loads are static, and one can argue that you can justify an impact factor, as the building code requires for things like elevators supports or crane hoist framing.
(BTW changing the slab thickness to 4", NONE of the expansion bolt anchors work... SMH)
He said a 6" is an overengineered slab for my use, but it wouldnt cost much more than the original plan that was suggested. Does this seem good to you. My area is pretty sandy, and the spot i'm putting the shop is above the grade of my house and detached garage.
Last edited by strutaeng; Sep 18, 2025 at 01:16 PM.
I'm meeting the concrete contractor today. if 5" saves a ton of money i'll be comfortable with it. if it's only a few hundred to go 6" I'll go overkill and feel better about it.
I guess this thread will now be the documentation of my new shop. Pulled around 30-40 trees by the roots over the weekend. Oak, Pine and sweetgum. The logger refused the load so I had the clearing company cut every tree into 10' logs and I moved it all to the woods to dry out some. Terrible timing for a burn ban! The excavator absolutely torched my grass and i still have a ton of clean up, but I'm 1 step closer. I couldn't get enough of this tractor in action.
the pad is done. 30'x50'x6" with 12" peremeter and around 10" poured for the first 16' of my left bay. I've already blown through the budget i set for myself. the thicker concrete was an extra 1.50 per sqft and i decided to add a 12x50 lean to which required a 12x12 beam to be laid for the legs to sit on. 20 loads of dirt had to be brought in at 150 per load. I'm $10,500 over budget and haven't even got to the electrical.
4-6 weeks lead time for the materials & building erection.
still needs electricity. I ended up adding a 12x50 lean-to. The slab is 6" with #4 rebar and the first 16' of the left bay was poured at 8" with 3500 psi slab.
Here is a sneak peak at the newest shop project. 1956 with A/C, heat and sniper EFI on a cammed SBC. Just a cruiser but i have an extra heads/cam/blown 6.0 laying around along with a spare 80e. Not sure if i care to hop it up though. The chassis and drivetrain is already built for the power if i decided to add some power. Don't know if i care to mess with it though. If i want to go fast or hit hard corners i can hop into the 69 Camaro or the WS6 trans-am. it looks good and sounds good. who cares about going fast anymore lol. I'm super happy to have a cool truck back into the fleet. The f-bodies are fun, and have become good investments but I'm a truck guy at heart. It's been a long time since I've had a cool truck and not just work horses.
Nice!!! Did you get it insulated or plan to have it done later?
closed cell spray foam ended up being cheaper over a fiber insulation through the company i selected. it will have central air and heat. electricity first, central air and heat next. 2 and 4 post lifts 3rd then closed cell foam to seal it all in. I'm already 15k over budget at this point and haven't paid for any of those items. I needed a lot of dirt and fill that i didnt anticipate.
My brother in law owns an A/C company so i get that at his cost+for contract labor. He'll have access to lifts if he ever needs them. a neighbor cut me a hell of a deal to clear land. i cant imagine what this would cost me if I hired a contractor to sub it all out. I've been fortunate enough to have contacts for almost everything. still over budget, but not upset. just naeve to what it would cost to do it right. i'm fortunate to be at a point in life that the broken budget isnt breaking me. my cheap *** is still upset about it though LOL.
the worst part is i've been burning trees since early november and i'm nowhere close to being done. The logger turned down my load of trees due to it being residential property and him not being able to fit an 18 wheeler down my driveway to pick it all up.
Last edited by TXsilverado; Mar 3, 2026 at 12:32 AM.
Sep 17, 2025 | 09:36 PM
