# concrete over concrete?



## angus242 (Oct 20, 2007)

superseal said:


> just like high performance tile jobs.


I use that on _all _my tile jobs. But I guess I'm just a Ferrari kinda guy :laughing:


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## superseal (Feb 4, 2009)

angus242 said:


> I use that on _all _my tile jobs. But I guess I'm just a Ferrari kinda guy :laughing:


Your profile says you were a gear head :thumbsup: so i'm thinkin' your right :biggrin::001_tongue::laughing:


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## JKBARR127 (Jan 13, 2010)

i agree w jomama. i would think a membrane between would be the only long term solution.


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## Diamond D. (Nov 12, 2009)

jkfox624 said:


> Agreed, in fact i thought ive seen on a box of coil stock before to not use it on concrete or around treated lumber.
> 
> This is out of the Building code requirements for structural concrete book from the american concrete institute.....
> 
> ...


 
Now i'm scared...
I used a peice of aluminum flashing last year on a box joist. So far no call back. I hope it just pushes the slab away from the door.


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## suzuki0702 (Feb 8, 2008)

aluminum is a definate no no. im liking the piece of rubber... think i have a piece of epdm layin around.:clap:


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## loneframer (Feb 13, 2009)

If the existing slab slopes toward the house, even if you use EPDM, any water finding its way between the slabs will still run toward the house and weep out the corners.

This leads to the potential of water finding its way behind the sidewall and causing a host of moisture related issues.

I'd consider building up the existing slab to pitch away from the house, then go with a waterproof membrane under the new pour.:thumbsup:


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## suzuki0702 (Feb 8, 2008)

i agree lone. im thinkin now of cutting a line in the old slab, tucking rubber in the cut, using geocell maybe another high quality rubber adhesive and running it up the wall, then placing an aluminum flashing on top of the new pad.


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## JimCarroll (May 3, 2010)

*sounds good*



jomama said:


> The only way I can see this remedy working long-term is by putting down 60 mil. rubber roofing between the slabs, ran up the wall above the new slab. The new slab is then merely protecting the rubber from damage. If you just pour a slab over the top w/o the rubber, the customer will be relying on caulk at the joints for the remainder of it's lifespan.


I saw a huge project a couple of years ago and this is what the engineer had the contractor do. they used a mastic with a peel and stick product on top of that.


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## suzuki0702 (Feb 8, 2008)

how will i bond the new pad to the old pad?


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## scrapecc (May 11, 2009)

Why do you feel the need to bond the pads together? Its not like the thing is gonna slide across the yard.


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## suzuki0702 (Feb 8, 2008)

a few previous posters recomended it... it shouldnt crack as long as i use mesh right? im just worried about the overlay cracking......?


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## scrapecc (May 11, 2009)

Concrete cracks. Thas what it does. Put control joints in it. I would use sand over the old, and maybe plastic over that then pour concrete. I usually use a #4 rebar matt spaced 2' on center. But that may be overkill.


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