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LBtechnology 04-19-2013 07:09 PM

New Patio - Pour over existing or demo?
Please see image:


Should we pour over existing patio, stairs and footers?

If not, why?

If so, what prep work should be done to the existing concrete and how do we ensure the new concrete doesn't crack around the existing? My gut is telling me the new will settle more and cause cracking around the border of the old.

Thank you!

joecaption 04-19-2013 08:04 PM

That drawing tells us nothing.
What's wrong with the old slab?
Trying to lay a new slab over an old failing slab never works out.

LBtechnology 04-19-2013 08:13 PM

There's nothing wrong with the old slab and it's the original from 1987.

The drawing shows the general dimensions and the layout of the concrete in question.

You are a welcoming kind of guy, huh?

If you join a web development forum to ask questions, maybe I'll be able to welcome you the same way. :wink:

stadry 04-20-2013 05:22 AM

wouldn't say ' never ' but overlaying the old slab after installing the new conc would probably be a better solution,,, the o'lay's only 1/8" thick so that shouldn't be a problem.

still important to know WHY the old slab's failing & how that's evidenced,,,

not that joe needs any defense as this topic's been address'd many times previously,,, IF i'd gotten to this thread yesterday AND been in the same mood as then, my reply would probably have been deleted by a more forgiving moderator as it was yesterday,,, many times threads are begun to validate the op's incorrect method/materials/etc,,, some tire of that sooner than others & more easily :eek:

oh'mike 04-20-2013 05:53 AM

I'm not a concrete guy--but I've got enough experience to offer an opinion---

Your new slab will not 'float' as it is fully supported by the footers-----if the old slab is supported the same way---your idea might work---

However, If it is a floating slab----which is typical of a patio---it will move more than the 'fixed' 'slab and a crack may form around the old slab as it moves---

Don't be to hard on Joe----He's not long on words sometimes--but he is asking for useful information----

stadry 04-20-2013 06:03 AM

as mike mentions, there will be a separation line showing between the old AND new conc,,, pay attn to design, interpretation, AND a good jnt pattern,,, these are critical to not hearing about failings from your bride :censored:

joed 04-20-2013 06:08 AM

Pouring over old concrete has in my experience always resulted in cracks in the new at the same place as the old work or cracks at the edge of the old work.

stadry 04-20-2013 06:19 AM

think joed's right,,, unless reflective cracking is properly address'd, the old crks can make a mess of the new conc,,, while that's his experience, ours is different,,, consider a bonded OR unbonded o'lay - also hybrid-polymer-modified cementitious thin o'lay

IF hgwys/parking lots can be successfully ' whitetopped ', i see no reason your project would be unsuccessful IF you're knowledgeable about the work,,, showing us here asking ?'s suggests differently

LBtechnology 04-20-2013 09:27 AM

I couldn't find any issues with the old slab. The existing footers from the old wood deck seem fine and so do the stairs. One of the stairs was crudely cemented to the existing patio so that will probably need to go.

We were told that the existing concrete patio is more than likely pinned to the foundation and that the same should be done with the new regardless of pour over or demo.

We are trying to determine whether we should pour over some, all or none of the existing concrete patio, stairs and old concrete footings.

joed - appreciate the answer

oh'mike - sounds like good info to me

itsreallyconc - Your font is difficult to read.

joecaption - I was ribbing, not kicking. But I have a feeling you realized that.

stadry 04-20-2013 09:54 AM

too bad as it was a really good response :yes: we do this work for a living

LBtechnology 04-20-2013 10:35 AM

itsreallyconc - I really do appreciate your help and help from others, but fonts like yours make reading forums difficult and pages messy.

Check out responses from joed and oh'mike - easy to read and they answered questions without any unnecessaries.

jomama45 04-20-2013 12:23 PM

I wouldn't pour over any existing slab or structures UNLESS I got 4" minimum gravel between the two to ensure separation. BUT, frost concerns are obviously a much larger concern here.........

stadry 04-22-2013 02:28 AM

you don't place any bonded overlays, joe ? not just poly-mod'd thin but 4" or 6", either ? ? ? that 4" separation - lateral OR vertical ? ? ? tnx, j

stadry 04-22-2013 02:33 AM

LB, you know what i forgot ? your slab should NEVER be attached to your structure,,, sorry for the brain****,,, ooops, forgot :huh: you won't read this 'cause its ' messy ' - darn :laughing:

oh'mike clearly sez he's not a concrete guy,,, even i read that part easily

LBtechnology 04-22-2013 01:19 PM

I agree, it shouldn't be connected and we will use an expansion joint. We will also remove all existing concrete and make sure the ground is prepared properly and the final slab has the appropriate grade. Now we need to consider stamping, texture, color, etc., or if we want it to be nice and simple concrete.

Now I have a good enough grasp to make a decision on the best company to hire.

Appreciate all the feedback.

itsreallyconc - I don't understand your purpose of using a font that is difficult to read and makes the page messy. That doesn't mean I didn't read what you had written.

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