Level a cracked concrete threshold...options?


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Old 10-06-10, 08:58 PM
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Question Level a cracked concrete threshold...options?

Recently had helical piers installed to raise/support a corner of the homes foundation. We expected the sliding patio door threshold was integral to the foundation and would follow along but it seems to have been a separate pour. This now needs to be leveled prior to me installing a new slider.

The 6"x82"x8" threshold is cracked in two places (1/2 & 1/3 locations). The full 1/2 piece remains nice and level while the two sections to the right sag to a total of 5/8". My question is: Since I can afford to build up the surface (even on the still level portion) 1/8"-1/4" is there a product that will allow me to basically skim coat the entire threshold level or, should I expect to rent a small demo jack hammer and remove enough or all of the existing concrete and pour anew? I'd prefer the former as I seem to understand skimming products have a much shorter cure time allowing for sooner install of the door into the gaping hole.

Thanks!
 
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Old 10-07-10, 05:00 PM
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Skim coat on concete is not a good idea. It just won't last. Chop & rebuild.
 
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Old 10-08-10, 04:46 PM
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Originally Posted by Pulpo
Skim coat on concete is not a good idea. It just won't last. Chop & rebuild.
Thanks for the reply Pulpo!

Not what I was hoping to hear but honestly, it's what I was expecting. Barring any decision changing insight being provided between now and Monday morning guess I'll prepare for a mini demo and pour job to start the week.
 
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Old 10-08-10, 05:59 PM
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I don't mean to contradict Pulpo's opinion, but there are several types of vinyl cement patch that bond well to properly prepared cement. Some recommend bonding agents to be painted on the cement first- you would just need to follow the directions- especially the part about how thick each coat can be applied. Many vinyl patches can only be applied in a maximum of 1/4" thick layers, so if you wanted 5/8" you would probably need to do it in 3 coats. When you layer it too thick it will want to shrink and crack, which can compromise the bond. You'd want to check the opening carefully with a 6ft level (or a 6' straightedge and a 4' level) to ensure you are getting an accurate reading across the entire opening. You might find that in addition to the filler, you might need to do some light grinding on the "level" portion. A 4 1/2" grinder and serrated diamond blade will remove an 1/8" of cement in a hurry.

Anytime you do this sort of work in a doorway you ought to plan on being prepared to board it up overnight with some plywood. Cement- even a thin vinyl patch- only dries so fast. Provided you do it properly I think it will last a good long time- especially since it's only purpose is to "shim" the door up to the right level.

Having installed doors for quite a few years, and having done it both ways, removing the cement below the door is usually a last resort for only the worst of scenarios. If you suspect your cement threshold is still moving, then patching it may not be the best solution. In that case, you'd probably want to remove, repplace it and install a rebar reinforcement down the center of it to help prevent any fracture from heaving the door.
 
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Old 10-09-10, 12:41 PM
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Much appreciate your reply XSleeper!

Appreciate your elaboration from experience. I was (and continue) researching the vinyl concrete patch route. They do seem to vary quite a bit in application between brands. Anywhere from 1/16" to 1/4" minimum thicknesses and 1/4" (between layers) to "unlimited/undefined" initial max thicknesses. The more I read the more it does look like a quite viable solution. With that said my self-debate seems to be reduced to a matter of confidence in results.

Seeing as that a bit of framing would be required even with the patch the only additional work, if I chose to replace the threshold completely, is probably 20 minutes of demo and a few minutes of rebar placement.

I know it sounds like I've made up my mind but I would be interested to hear your opinion as to any major negatives to the replacement route. Your preference to rebuild rather than replace has me wondering if I could be opening a can of worms in possible hidden pitfalls or, are we simply talking additional "expected" work?
 
 

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