Existing concrete floor questions.

[oldtinsmith]

I built my pole building in 2005 and had it closed in by april of 2006. The top soil had aready been removed and a layer of clean sand (8"0) was compacted in its place. A cement contractor leveled the sand and readied it for 4 full inches of cement. The cement I bought was 4000PSI NA C338 S1 with an addition of polypropelene fibers. The 4 boxes (3' x 4') are areas where the cement was poured to a depth of 6". They were there for a little extra cement under possible future car lift(s). I wasn't home when they did the saw cuts. ...Now to jump from 5 / 5 / 2006 to today! ... After all these years, I don't have a single crack anywhere in the cement floor! I'd like to install a lift in the center bay BUT, the saw cuts scare me!!!Please give me some thoughts and ideas. ... On 1 / 18 / 2017 in the forum "Light fixture layout collection (post #336) are a few pictures of my messy shop!

Doug

 

[Ralf11]

you want that lift

I thought sand went on top of crushed rock?

 

[ConCretin]

I don’t want to add to your anxiety but you probably do have a number of cracks in your floor, you just can’t see them because your control joints did their job and induced cracks where they weren’t visible.

With that said, most lift manufacturers specify minimum allowable distances from lift anchors to control joints. You ought to be able to locate your lift accordingly. Now get that lift installed and start enjoying it.

 

[Jlbc212]

Why not place the lift in the left bay? That extra depth in the garage will make it easier to work on vehicles.

 

[Beemer]

My degree of concern would be based on the type of lift. Obviously 2 post lifts are trickier than 4 post lifts when it comes to base support.

If you're inflexible in your plans and can't justify the loads you could always remove enough slab to pour a new area without joints in compromising places in the needed areas. A bit of figuring is in order to determine how much continuous slab is needed for each leg; more or less a footing design calc.

 

[nadogail]

IMHO, Concrete floors come with only two guarantees; They will crack and nobody will steal them.

 

[oldtinsmith]

LLWillysfan,,, I've been reading you post "The Concrete Underground" (many times!)! It's a good read! Thankyou!