# Crumbling on the exterior concrete slab foundation



## Lynhira (Apr 1, 2012)

I have a 10 year old townhouse and it has a concrete slab foundation.  The part of the exposed foundation from the siding to the ground is crumbling pretty badly I think.  
I also have a crack in my driveway concrete that goes from side to side, my driveway is a hill, I do not know if this makes a difference or not.

How can I repair these myself?

The picture that looks wet is because it is right under the back faucet on the patio and I cleaned the patio using water today, it is not normally we like that.


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## nealtw (Apr 1, 2012)

The foundation is not crumbling away, what you have is called honeycomb, caused be air getting trapped in the forms when the concrete was put in. It does not appear to be deap enouph to worry about and it was there for the building inspector to see when the house was built and he would have had it fixed if it was bad.
The crack in the driveway could be cleaned up with a grinder and filled with a none shrink grout. The fill under driveways does move  and more so when it is on a hill so this will happen, most time a driveway will have control line troweled into them so it can crack on those line and not be so unsightly.


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## BridgeMan (Apr 2, 2012)

Wouldn't be a bad idea to clean up (meaning improve the look of) the honeycomb by thoroughly wire-brushing any dirt and algae off it, and then work in some stiff mortar with a wood hand float.  You can buy premixed mortar in bags at most big box stores.  Just add water (not too much, as you want it to be sticky) and vigorously stir.  Make sure the mix has lime in it, which helps to hold the wet mortar up vertically against the slab until it hardens and sets.  This is something you could do yourself, but it will take some physical effort (upper arm strength) to work the stuff into the voids enough so it can "grab."  Wear a good pair of rubber gloves, as lime can burn the skin after prolonged exposure.  And don't forget a good pair of knee pads, too.  If nothing else, properly covering the honeycomb will mean one less thing to slow down the sale of your place in the future, and possibly make it worth slightly more to the average buyer.

If the driveway crack is fairly wide (meaning more than 1/8" or so), you could fill it as nealtw suggested.  I'd be tempted to forget the grinding and rather use a hand wire brush.  Doing so will leave the crack faces rough to provide a good bond.  An easier repair would be to dribble in some liquid crack repair products, although I'm not familiar with a brand having a good track record.  If the crack is narrower, I'd leave it as is and not worry about it.


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## Lynhira (Apr 3, 2012)

Thank you so much guys, that sets my heart at ease to know that the honeycomb as you call it is nothing too bad.  Yes I do want to do something to improve the look.  So I will do what you suggest.  Appreciate your help so much.


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## nealtw (Apr 5, 2012)

I would not attempt a repair on the honeycomb. When the concrete has bad honeycomb the inspector will require repairs be made and every little bit like yours is touched up. A sharp home inspector will see patches and know there was something bad enough to be fixed. If the same inspector sees a little honey comb he will know there was nothing seriously wrong with rest of the foundation.


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## BridgeMan (Apr 6, 2012)

I would repair the honeycomb.  A properly-performed repair doesn't have to look like a patch (by dressing the entire face with a skim coat of the same material), and if nothing else, doing so will minimize the chance of more algae and dirt collecting in the voids.  

The property owner's satisfaction in removing the deficiency also comes into play.  By spending a few dollars and some of her time, she will feel better about improving the looks (and value) of her place.


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## Andrew1994607 (Nov 13, 2012)

Lynhira.   I have same problem on 1yr old house   Warranty inspection tells me it's ok and they patch it.   So don't worry.    btw. You are hot.


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## BridgeMan (Nov 14, 2012)

All right, Andrew--exactly why did it take you more than 7 months to realize she's "hot"?  Maybe that's just her normal look.  From her night job at the pole-dancing place.


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## itsreallyconc (Dec 1, 2012)

IF you do repair the honeycombed area ( probably from lack of vibration/poor consolidation when the conc was placed ), make the repairs ALL the way - in other words, peel back some sod so the patch, when finished, will appear to be solid    the d/w crk is probably due to improper jointing,,, i'd run a 4" grinder & .375 blade in it deepening it to 3/8" depth - lay 1/4" tape on the btm of the cleaned sawcut - then seal w/100% silicone,,, you can't hide the crk other than replacing the conc,,, at least that's what we did for over 35yrs,,, i have seen these issues many times even when the homes were owned by less attractive wimmins  :banana:


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## ladychichevy (Jun 12, 2013)

Experiencing something similar. I dig as far down around the perimeter as I can or to a cpl inches below where I don't see the spalling anymore. I've been knocking off the excess loose concrete with anything hard enough, a tire iron, hammer whatever. Then scrape off excess loose rocks/concrete with a stiff wire brush. Brush off with a little hand broom. Then wet the area with some water. I didn't use mortar but some hydraulic cement (Quickrete) mixed it up until in was kinda soupy (it sets up VERY VERY quickly) I found making it soupier give me a little extra time to work with it. I use a trowel and something to catch it from falling and smooth it (I have no idea what its called, I'm new to this whole repair thing). Take a wet sponge and smooth it out. So far so good. Only issue is it a little uneven (probably from me not evenly applying the concrete) but its up there and looks much better than the large chunks and jaggedness of the crumbling. I'm going to follow up with some waterproof paint. TI was also recommended that I get and interior drainage system. Idk what to do about your driveway...try watching some youtube videos they are awesome.

I know your post is kinda old so what did you wind up doing?


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