Pouring concrete over existing slab?

[rekees4300]

What do you think?

There is some good advice at the Quikrete website or you can call them at 1-800-282-5828.

QUIKRETEｮ - Frequently Asked Questions

 

[GPintheMitten]

Thanks for all the advice and links.
Now to try and sort through it all.

 

[tlbuser]

Since you're pouring a new floor, I would definitely run conduit for electrical and maybe even cut out some of the old for exhaust ducting under the new. Nice not having overhead obstructions when moving stuff around the shop.

 

[GPintheMitten]

Regarding exhaust, are talking about saw dust collection system?

 

[ruren]

I have a building out back that was built on a slab. It is about 14x26. The old slab is cracked. I am considering moving my wood working tools out there and want to be able to move them around on rollers. There won't be any vehicles driving or parked in there.

What do you think?

I would say it depends on how bad the slab is cracked. If minor cracking that is stable (not moving around) a 2" topping slab with the proper concrete mix would be appropriate and would give you a smooth surface. If the cracking is more severe and they keep moving they will just telegraph through this in short order and a full 4" slab with something to break the bond (sand bed or at least a membrane) would likely be more successful.

If you are not in a hurry the best way to tell if the cracks are truly stable is to use crack monitors like this:

[ame]http://www.amazon.com/CrackMON-Concrete-Crack-Monitor-Kit/dp/B0049MAVYU[/ame]

You mount them across the crack and check them on a regular basis to see if the cracks move over time with seasonal changes and such.

 

[flusher]

I have a building out back that was built on a slab. It is about 14x26. The old slab is cracked. I am considering moving my wood working tools out there and want to be able to move them around on rollers. There won't be any vehicles driving or parked in there.

What do you think?

How many tools are we talking about?
If it's just a few and the floor is cracked but still servicable, I'd probably add pneumatic tires and screw jacks to the tools and forget about refurbishing the slab.

 

[Jbbies]

I do lots of woodworking and my dream is to someday have a wood shop with wood floors, much nicer on your feet and warmer. Do you think there is a way to lay down sleepers and put a sub floor over it for your woodshop?

 

[GPintheMitten]

I do lots of woodworking and my dream is to someday have a wood shop with wood floors, much nicer on your feet and warmer. Do you think there is a way to lay down sleepers and put a sub floor over it for your woodshop?

Yes! Good idea. I don't know why I didn't think of that. In the past I, too, have thought that a wood floor would be ideal in a wood shop.

Many years ago I helped my brother-in-law put in a wood floor with sleepers in his commercial building basement. We had to taper the sleepers because he had multiple floor drains.

I could add some styrofoam insulation between the sleepers while I'm doing it.

It wouldn't double as tractor and boat storage but I can build a lean on it for that.

Anybody see a problem with this approach? Do you think I should put visquine down on the concrete before the sleepers? I would use treated 2x4's for the sleepers.

 

[Egon]

Surely sounds like an idea.

Any concerns of undesirable substances collecting under the wooden flooring?

 

[JB4310]

As long as it's above grade I don't see a problem, Wood floor below grade is a science experiment waiting to happen. I'd rather have the concrete for it's fire resistance, but if you are strictly doing wood work, no welding or grinding etc could be an alternative.

You wouldn't need anything on the concrete, you wouldn't even need PT for the sleepers if the slab is high and dry, but I'd probably use pt anyway.
2x4 sleeper no more than 16" OC, 3/4" T&G plywood. I'm not sure on the insulation, but if it is a humid area maybe a plastic vapor barrier over the concrete and insulation would be called for.

If you did concrete, no need to bond or tie, just pour 3-4 inches of concrete and cut joints on 10 ft, you could put a wire mesh in the new slab, but probably not necessary.

JB