Concrete slabs and 2 post hoist

[albanycobra]

Hey Fella's

I am planning on installing a Tuff Lift 2 post hoist in my shed. My slab is about 8 years old and 100mm concrete with steel reinforcement. Do you think this slab is up to handling a hoist? How do I test to see the compression strenght?

[d488y2]

This is from The tuff lift manual, hopefully it helps?

Consult building owner and / or architect’s plans when applicable to establish the best lift location. The lift should be located on a relatively level floor with 4” (102mm) minimum thickness, 3000-psi concrete slab that has been properly cured. There can be no cracks in the slab within 36 in. (914mm) of the base plate location, and no seams in the foundation within 6 in. (152mm) of its location! Remember: any structure is only as strong as the foundation on which it is located!

[Ron61]

I am not an engineer but I can tell you what happened to a friend of mine and he wound up getting a 4 post lift. The company came out and checked his slab and it was reinforced with rebar and 4 inches thick, so they said it would work just fine. After about a month the lift post on one side started breaking the slab and it actually started to pull up a little. He called them and they looked at it and said they had never seen that happen, but they took that lift our, cut out that spot in the floor and fixed it, and then sold him the 4 post lift and took the full price of the 2 post one off the 4 post price. I don't remember the brand of lift but not many companies here would do that and I doubt if any would now.

Ron

[muzzza]

Originally Posted by albanycobra

Hey Fella's

I am planning on installing a Tuff Lift 2 post hoist in my shed. My slab is about 8 years old and 100mm concrete with steel reinforcement. Do you think this slab is up to handling a hoist? How do I test to see the compression strenght?

Cantilever forces imposed on concrete slab can be quite severe - especially when you and the Mate are hauling and swinging on a gearbox, under a car 2.0m above your head !!!

" Tufflift" spec sounds minimal at best. I would cut slab out beneath each post ( say 800 x 800 - depends on anchor bolt layout )
Bore min 450 dia pier, down at least 900 deep. Toss in some reo ( 4Y12 cage would do ) and use nominated tie down bolts, with at least 300 embedment.
( anchor bolts supplied may not be long enough ) Hook tie down bolts into pier reinforcing with plate cleats or similar.
25mpa conc to pier, with a bit of F72 mesh to new slab infills.
Key new slab infill to existing slab if possible.
Make a dummy base plate in ply or something to get it all jigged up.

May sound extreme, but I had a good Mate killed under a hoist.
Distance to edge of slab may be an issue also ??

Murray QBCC Lic Building Designer

[Detroit Bill]

Originally Posted by muzzza

Cantilever forces imposed on concrete slab can be quite severe - especially when you and the Mate are hauling and swinging on a gearbox, under a car 2.0m above your head !!!

" Tufflift" spec sounds minimal at best. I would cut slab out beneath each post ( say 800 x 800 - depends on anchor bolt layout )
Bore min 450 dia pier, down at least 900 deep. Toss in some reo ( 4Y12 cage would do ) and use nominated tie down bolts, with at least 300 embedment.
( anchor bolts supplied may not be long enough ) Hook tie down bolts into pier reinforcing with plate cleats or similar.
25mpa conc to pier, with a bit of F72 mesh to new slab infills.
Key new slab infill to existing slab if possible.
Make a dummy base plate in ply or something to get it all jigged up.

May sound extreme, but I had a good Mate killed under a hoist.
Distance to edge of slab may be an issue also ??

Murray QBCC Lic Building Designer

This sounds like a good plan. The idea of a lift is to feel good and be safe about it when you are under the car.

[Bernica]

Originally Posted by muzzza

I would cut slab out beneath each post ( say 800 x 800 - depends on anchor bolt layout )
Bore min 450 dia pier, down at least 900 deep. Toss in some reo ( 4Y12 cage would do ) and use nominated tie down bolts, with at least 300 embedment.
( anchor bolts supplied may not be long enough ) Hook tie down bolts into pier reinforcing with plate cleats or similar.
25mpa conc to pier, with a bit of F72 mesh to new slab infills.
Key new slab infill to existing slab if possible.
Make a dummy base plate in ply or something to get it all jigged up.

May sound extreme, but I had a good Mate killed under a hoist.
Distance to edge of slab may be an issue also ??

Murray QBCC Lic Building Designer

Muzzza is right on point! I would do this and maybe even more if I was using a 2-post. I would also drill into the sides of existing slab and use rebar to dowel into them. Use epoxy grout when you insert the dowels, then order a good mix of 4,000 PSI or higher mix for the footings. And chuck the anchor bolts and use long J-bolt anchors. The deeper the footing, the more the safety factor.

My 2 cents

[Tim7139]

This isn't that hard. lag a large intermediate plate to the floor and then lag bolt the lift plate through the base plate and into the concrete.
Easier still, get a four post setup which you don't need to bolt down at all and is far , far safer.

[Detroit Bill]

I am not saying to get a 4 post but it does have some advantages.


http://www.challengerlifts.com/pdf/home_enthusiast.pdf

I have a Challenger 4 post for home and their RJ 4.5 rolling jack. The jack is not as versatile as far as pad placement for the lifting points. If you need to lift towards the center as I do you need to make pads for the center of the jack. If you need to reach out further than the jack can reach (which is the case on my Porsche 911) you are out of luck.

A big benefit is that it is car storage and you can park underneath it, without too much trouble which I do. And it is much easier to lift the car in general.

Many of the two posts on the market are Chinese crap. I went with a known brand so I got Chinese crap that has been vetted by a company that knows about lifts.

Good luck!

[mikeinatlanta]

My 4" thick slab ended up being less than 2" in the middle when we cut it open. muzzza has the right idea.

[Bernica]

I tend to do overkill and error on the safety side. I live in earthquake country and that always makes you think as well.

[LoBelly]

I have a Tuff-Lift hoist in my shed - it has been there for about 2 yrs
the hoist is a lower end model with a base plate, pad height adjustment is via tubular extensions under the lift pads and the catches have to be individually released from both sides (but it fit in my shed )

When it was being fitted the drill punched through the concrete at least once - the depth of the concrete was measured and was bang on whatever the minimum was.

The fitter was very particular on this for each bolt as well as checking the distances to edge of slab - for one bolt there was concern that it was not tightening enough - but then it did and was pronounced 'OK'.

Generally my experience with the company and installer was positive

LoBelly

[07cob]

I also have a TuffLift hoist and it has been installed into a 100mm slab in a shed that was here when we bought our house so no idea of the concrete strength. As such and for peace of mind, the hoist has been positioned such that it is also braced at the top of both uprights. Otherwise, the concrete would have been cut as above.

Geof

[albanycobra]

Hi Geof , I know I have a good slab, I watched it go down. I dont know the strenght, I only know it has wire in it and is 100mm thick. I am going to install as per the Tuff. I went for the base model short single phase job.
Would love a pic of your hoist installed, especially the upper bracing as I just talking to someone about bracing the the top of the hoist to the shed walls. The closet edge to my hoist 3.5m. I think it will be fine....

[stiffy]

Albanycobra,

I have a 2 and 4 post Tuff-Lift hoist in my shed.

The 2 poster is set with 500mm 32mpa foundation and 100mm 32mpa slab,

It is not going anywhere.

They have been installed for 5 years and get used weekly. The

Cobra/Daytona are very light cars (1100/1300KG's) BUT I do put my 2500kg

Rangie on the 2 poster, it does look stable but I dont eat my lunch under it....


STIFFY

[BMK]

Mmm Rangie - I need to be selling copiers!!

[FatBoy]

You need to get a new Rangie, they're 600kg lighter than the old model.

I would still be very nervous of putting mine on a 2 post lift though.

Paul

[07cob]

Originally Posted by albanycobra

Hi Geof, Would love a pic of your hoist installed, especially the upper bracing as I just talking to someone about bracing the the top of the hoist to the shed walls.

albanycobra

Here are a couple of images. Just don't mind the mess!





Geof

[albanycobra]

Cool. Cheers