Pouring concrete over existing slab?

[Jbbies]

What I like about it is, you can set up dust collection and wiring in it so cords are out of the way. If you do this send us pictures.

 

[arsenix2001]

Heres my :2cents: take it for what its worth. I installed structual slabs and foundations for 8 years and ran across this quite often. Normally its remove compact, regravel, replace. In your case if it were my house, eddie is correct, i would NEVER tie the new slab to the old one. Its cracking due to uneven settling most likely. The new slab would follow suit if its not finished sinking yet, or be stressed in freeze that cycles at the crack points. You would actually want to create a break between the two slabs, this can easily be done by rollinh out 6 mil plastic over the old slab in prep to pour the new one. What you essentally will have now is a floating slab laying on the other one, and this calls for it to be structual. Wire mesh wont cut it here. Use grade 40 number 4 rebar (1/2 inch) 12" OC in both directions so you have a nice grid. Tie it up with wire and use rebar chairs to be assured the bar stays at the proper height during the pour. I would use minimum of 3500 psi concrete air entrained, and fiber isnt nessesary but it cant hurt. We used to only use fiber on pool decks to avoid having a bonding inspection done on the rebar. Good luck with the project!

 

[GPintheMitten]

arsenix2001, thanks for sharing your expertise. What you describe sounds like the right way to go if I pour concrete as stated in my original post.

Right now, I'm starting to lean toward putting in 2x4 sleepers and plywood floor glued and screwed. But I haven't really decided yet. I need to price out both options and then consider the advantages to each.

And thanks everyone for your help. This site is a good one for sharing experiences and ideas.

 

[arsenix2001]

arsenix2001, thanks for sharing your expertise. What you describe sounds like the right way to go if I pour concrete as stated in my original post.

Right now, I'm starting to lean toward putting in 2x4 sleepers and plywood floor glued and screwed. But I haven't really decided yet. I need to price out both options and then consider the advantages to each.

And thanks everyone for your help. This site is a good one for sharing experiences and ideas.

Your welcome, let us know what you decide.

 

[CurlyDave]

I'm starting to lean toward putting in 2x4 sleepers and plywood floor glued and screwed.

If I were doing this I would screw the plywood down, but not glue it.

I recently had a situation where I used 3/4" OSB over gravel as a floor in a garage while I built a house. The OSB was only laid down on the gravel and the pieces were cut to fit but no extraordinary care was taken. Lasted for a year and then took it up and poured a concrete slab.

There was no apparent movement during the year I used it just loose laid on the gravel. The big advantage of not gluing is that if only one piece needs to be replaced it is easy to do. Glue it down and it is very permanent.

 

[MyJoBota]

If you choose to go with a wood floor will you have enough ceiling height accomodate the raised floor?

 

[tlbuser]

Regarding exhaust, are talking about saw dust collection system?

Yes, everything possible out of the way. Nothing overhead to worry about and no tripping obstacles. Having all of the tool (table) tops at the same height is helpful too. For limited space, mobile bases are great because you can just wheel things out of the way.

 

[GPintheMitten]

Good point on not gluing the ply down.

There will be enough height and it would be about the same by pouring another slab as putting down wood floor.

 

[Redneck in training]

google Garage floor such as
Gladiator Garageworks Tile Flooring - Silver - 4-pack | Wayfair
or this
http://www.racedeck.com/residential.html