Thread: Measure concrete slab thickness

I'd be seeking the advice of a structural engineer....given the loads imposed by the hoist, slab thickness might not be an issue.

Probably only 50mm in the centre if it was just an infill.
Get a hammer drill and drill a hole through it. The edges would hopfully be a minimum of 300-500mm deep.
If it's only 50mm I'd be beefing it up under the supports.
Cut out a 500x500mm square and dig a hole about 600mm deep. Put some reo bars in and dowel into the existing slab to tie it all in fill with like 25mpa crete. Should only be a day job if you hire a demo saw and post hole digger.
Even if it's 100mm thick I'd still be cautious with the hoist.
I wouldn't waste your money on an engineer it could open a can of worms but that's up to if you go down that path.

Wish I had a hoist lucky bastard!

Cheers Jim

Originally Posted by LRJim

I wouldn't waste your money on an engineer it could open a can of worms but that's up to if you go down that path.

Cheers Jim

Goodness me no!

If it's money that's a problem then I agree.

If it's an issue of safety then LRJim can be held liable for the advice he's just given when the hoist falls over and kills someone.

You could use ultrasonics, radiography or ground penetrating radar to test the thickness in a non destructive way - all of which would most likely be more expensive to get someone to do then just whacking a drill into the slab and checking yourself.

Agree with Jim. Most garage slabs max thickness is 100mm. Last thing you want is your pride leaning against the garage wall because the hoist has gone through the ground. Measure your mounting area cut dig and do it to spec .

Thanks all for your quick replies.

The shed was a farm machinery shed and workshop so I am hoping the centre slab could be more than 100mm thick.
If it is 150mm or more then I plan to mount the hoist directly. Any less and further foundation work will be required.

So drill it is.

Originally Posted by one_iota

Goodness me no!

If it's money that's a problem then I agree.

If it's an issue of safety then LRJim can be held liable for the advice he's just given when the hoist falls over and kills someone.

I'm sure that will hold up well in court.
"A guy on a land rover forum said it will be fine"
Don't we take all advice on this forum at our own risk?

Another option is to get some 20mm plate and spread the weight over a larger area.

But don't take my advice you will get yourself killed.

Originally Posted by LRJim

I'm sure that will hold up well in court.
"A guy on a land rover forum said it will be fine"
Don't we take all advice on this forum at our own risk?

Another option is to get some 20mm plate and spread the weight over a larger area.

But don't take my advice you will get yourself killed.

Well I'd have to take the advice of a lawyer to be sure of that. That would be much more expensive than an engineer. ;-)