new concrete floor info wanted

[DSFM01]

Okay did the search feature and either have no clue how to word the search correctly or just not finding what I'm looking for.

So here it goes. We are having a new concrete floor put in the shop. The area being replaced will have a new twin post lift installed. Presently the lift chosen is a Rotary asymetrical 9k twin post. We are getting conflicting thoughts on how the floor and subsurface should be constructed. Any experts want to weigh in on this or at least point me to threads already covering this?
Location of floor will be in Central Illinois and is in a heated shop. Also in past the present floor "sweats" fairly bad in the spring. I am open to all ideas about insulation, vapor barriers, or ____??

 

[bazzateer]

I'd just ask the lift manufacturer what they recommend for their lift. If they say 6" I'd go for 8" and so on thus over-engineering it.

 

[Zeke]

I 2nd going to the manf'r for specs. And, since you have the chance, embedded floor attachments are always better than drilling a retrofitting. Remember that concrete takes 30 days to reach the PSI it was designed for. It will get even stronger over time, but putting a big load on it in the first week is not wise.

Someone else is probably more qualified to explain rebar placement to spread out the stress at the base of the posts.

 

[brownbagg]

and use a vapor barrier

 

[DSFM01]

Tomorrow I will post some information from one of the bids.

 

[64dragnwagon]

I 2nd going to the manf'r for specs. And, since you have the chance, embedded floor attachments are always better than drilling a retrofitting. Remember that concrete takes 30 days to reach the PSI it was designed for. It will get even stronger over time, but putting a big load on it in the first week is not wise.

Someone else is probably more qualified to explain rebar placement to spread out the stress at the base of the posts.

I had assumed this was the case myself. I am getting ready to pour a new floor and also putting in a 2 post lift. I called Greg Smith equipment since I think that is where I amy order one and asked them about a pattern to use for me to sink some j bolts into the wet concrete. They told me that that is NOT the best way to do it. I was surprised but they told me the hardware they send is the strongest way to install the lift. I can't see why they would be biased and give me bad advice. I still question their logic though, maybe someone can explain.

 

[73 Mustang Bill]

I've never set the anchors in wet concrete, and I never would have it done. The concrete guys are not that precise, and there is no way that they are going to get them in the right place, square, etc. Drop in anchors are really strong, or if you are really worried about it, use the epoxied in anchors. Installed correctly, they are super-strong.

Having just been through it, measure, remeasure, and measure it again, for the depth that they are pouring your concrete, before they even call in for concrete. I had to have fill dirt in my garage before they poured the floor. I told the concrete guy that I was putting in a lift that needed a minimum of 4 inches (like the plans said), and that I'd prefer 5 inches and would pay the difference. He said I was getting 5-1/2" deep. That was 2 years ago. I recently drilled holes for my MaxJax, and found the concrte was 3-3/8 inches deep. Plans said 4 inches, so I called the builder and he didn't fight me at all on fixing it. The concrete sub said that they were just hired to do the labor, and that it was the builders fault. I didn't call him on it, but the concrete guy was the one putting in the fill dirt, and is the one that ordered the concrete. The order that was placed was over a cubic yard short of what was needed at 4 inches, so he had to have known that I wasn't getting 4 inches, much less 5-1/2". So, in saving that $100 in concrete the first time, I made them come out and cut a 4' x 12 patch, and fill it to 12 inches deep with 3500 psi concrete, with rebar in the bottom 6 inches. I checked that the hole was 12 inches deep, and checked with the concrete driver to make sure it was 3500 psi concrete.

The concrete guy said that when they know a lift is going in, they will make the pad thicker in that area. I checked my pictures, and there were no indentations like that. I should have shot the height of the dirt with a laser before they poured it. It would have been obvious that they screwed up, or where trying to short me. Most people probably would never know that their floor is only 3-3/8" deep, but I found out. It costs them a couple bucks to fix it.

 

[Parrish416]

I'd just ask the lift manufacturer what they recommend for their lift.

 

[rburke65]

Go to the source....the mfg.

 

[ConCretin]

This would be my 'shortlist' for a durable floor.

• Well drained and compacted granular base 8"-12" thick
• 15 mil vapor barrier such as Stegowrap with taped seams
• #4 rebar at 12" on center in both directions supported at mid span on chairs
• Min 4" of 3,000 psi non-air entrained concrete w/ min 3/4" aggregate
• Midrange water reducer with a max slump of 6"
• Place in moderate temps on a cloudy, windless day (ok, this one might be tough but so is finishing a slab on a hot, sunny, windy day)
• Professional finishing crew that knows what bleed water is and can finish w/o adding water to surface
• Control joints cut to 1/4 of slab depth @ 10'-16' centers immediately after finishing using an early entry saw
• Moist cure for 7 days

This is obviously not a complete list and a couple items might be overkill but it will get you a great slab 99% of the time.

Good luck with your project

 

[6768rogues]

If the floor sweats in the spring, it could be warm moist spring air contacting the relatively cool floor. If that is the case, a vapor retarder will not solve it. Mine does it for a short time in the spring. I pull the cars out, leave the doors open and use the opportunity to clean the place up. After the concrete warms up, it does not sweat for the remainder of the year.

 

[NUTTSGT]

I'd say like a few others, ask the manufacutrer.

Yet I'll throw this in too, when in doubt, OVERKILL.

 

[Zeke]

One good way to ensure any embedded attachments are spot on is to make a plywood template and run bolts into the receptors. Long bolts so you can still trowel under the template.

One reason they don't like J-bolts is because the J-bolt is designed to be placed deep. In most applications the J part would end up in the dirt. You need shallow attachments.

I would prefer a flush attachment like a T-nut or threaded coupler welded to horizontally placed bars. When the lift is moved there is nothing to cut or trip over.

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