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Buying House, Basement Ceiling under Garage Crumbled One Spot Rebar Showing

Buying House, Basement Ceiling under Garage Crumbled One Spot Rebar Showing

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Old 08-20-12, 01:45 PM
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Buying House, Basement Ceiling under Garage Crumbled One Spot Rebar Showing

Hi,

I was looking to buy a house and we found one we love. It has a great basement that leads out into the yard. However, the garage is over part of the basement and when inspecting the ceiling, the concrete had started crumbling in a few spot and the rebar was showing. The house is 50 years old and parts have been redone over time so I do not know how old this is. There is a large concrete support beam going all the way across the garage.

Is this fixable or is this a... STAY AWAY dealbreaker.

Any help would be greatly appreciated.

Here is a link to a picture:
http://photos0.mlswis.com/met/201208...05000000-o.jpg
 
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  #2  
Old 08-20-12, 03:21 PM
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Welcome to the forums! Sometimes rebar is allowed to rest on the bottom of the form, or is crushed down there by the sheer force of the concrete being installed. By being on the bottom, there isn't much concrete between it and you, so it will spall and part of the concrete will break away from the area. It appears to have happened here. I don't think this is a real deal breaker, as you can spray the rebar with a rust inhibitor, and once it has dried, concrete patch could be troweled over the area. Do you plan on installing a drop ceiling or anything in this area in the future? If you have plans for it, I wouldn't do anything but the rust inhibitor, which will turn the rebar black.
 
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Old 08-20-12, 04:15 PM
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I am more worried about the structural integrity of the ceiling as it is below the garage. The last thing I want is to have my toyota to become a permanent fixture in my basement OR for me to be crushed by it when i am napping in my mancave.

I thought it could be corrosion of the rebar thus undermining the sternght of the ceiling.
 
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Old 08-20-12, 10:48 PM
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A few close-up pix of the corroding rebar would help in determining if it appears there's a substantial section-loss problem. I'd make a determination of the thickness of the ceiling, and poke around on it from below and the top side to see if it has a nice, sound ring to it, as opposed to giving off a dull thud. Hollow-sounding delaminations indicate you could be facing major future costs of replacing the entire floor/ceiling. And if it's only 3" thick, there's definitely a potential for performance problems. But if the rest of the place is a winner, complete replacement wouldn't scare me away. Just factor in the costs with your offering price.

But I'm an engineer who's been evaluating deteriorating concrete for more than 40 years, so maybe my vote doesn't count. If in doubt, hire a local engineer who can spend an hour or so looking the thing over, and give you a written report suggesting what to do. Money well spent, along with providing validation for your lower offering price.

P.S. I'm drooling over your future man-cave. Super nice layout, and the haunched CIP girder ends indicate that the ceiling and its support system were designed by someone who knew what they were doing. Something not seen too often these days, and a very good sign.
 
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Old 08-21-12, 09:16 PM
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Here are some more pictures

ImageShack Album - 11 images
 
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Old 08-22-12, 02:53 AM
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I think you have less of a problem than originally anticipated. The rusted areas appear to be ill placed conduit for electrical and not rebar at all. Look at the electrical boxes in the ceiling and you can trace the conduit from them to each other. I think this man cave is going to be good to go. Bridgeman, comments????
 
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Old 08-22-12, 10:15 AM
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I contacted another engineer who said he had actually been to that house before when the bank remodeled... He said water had gotten in the conduits and rusted them out shilling the concrete.

He did not know if rebar was damaged but he assumes if there is water in the conduits the rebar would be affected. At the time he suggested to the remodeler to contact someone and have it fixed using "shotconcrete", a product that they shoot into the slab to enforce it and potentially add a beam and a pillar.

I am a bit shocked that the previous remodeler knew about this and disregarded the advice of the structural engineer he hired.

I have another engineer coming in tonight to take a look to get a second oppinion.

Thanks a lot for all the advice btw, keep it coming. Some people here have really helped break, or should i say, crack the ceiling on this case.
 
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Old 08-22-12, 11:46 AM
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Way too much cracking and delamination going on at the underside to suggest there's not a problem. Too bad that plastic conduit and junction boxes weren't used. Although I initially mistook some of the rusty conduit as being rebar, it's logical to assume that if chloride infiltration made it all the way through the slab to heavily corrode galvanized steel conduit and junction boxes on the bottom, it's not hard to visualize the extent of damage to reinforcing steel mat(s) in the slab interior (that wouldn't have been galvanized). Walking the entire garage floor with a chain drag would tell the story, making it possible to determine if the topside is delaminated to the extent that slab removal/replacement would be required. The topside photo of the rectangular concrete patch along a parked vehicle's wheelpath indicates that spalling and surface delamination were present at one time, but were repaired.

Regarding shotcrete, I've seen far too many instances of it failing as a concrete repair material for me to have much faith in it. And trying to evaluate concrete/structural deterioration from a distance isn't always easy.
 
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Old 08-22-12, 02:09 PM
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The rusty metal is clearly the remains of a poured-in-place lighting system that should have been built with different materials. That said, there's an unusual amount of damage around it for an interior space. And that, plus the existing repairs and other problems that Bridgeman pointed out indicate a need to thoroughly evaluate this slab before making an offer.
 
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Old 08-22-12, 06:19 PM
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I didn't mean to intimate that there was no problem, but that the metal didn't appear to be rebar, but conduit that should not have been used in the first place due to the acidic nature of concrete.
 
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Old 08-23-12, 04:24 AM
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The structural engineer came to look at it and said that there is damage, obviously.

He suggested jack hammering the areas affected and plugging them, perhaps replacing affected rebar above the conduits with new metal bars and weld then t unaffected areas.

Worst cast he said you have to put 5 metal beams on each side and potentially a pillar. Worst case he indicated 20k, best case 5k.
 
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Old 08-23-12, 07:04 PM
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Billie--So what will be your next move? A lot of us are eager to know how this turns out.

chandler--Regarding pH levels, could it be that Georgia concrete is different from that in the rest of the country (or world)? I've never heard of acidic concrete in the 40+ years I've worked with the stuff. The pH level of fresh mud is typically high, at 12 or 13, while cured concrete can drop to as low as 8. Acidic would be anything less than 7.
 
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Old 08-25-12, 07:04 AM
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We put in a bid for the house.

There were a couple of options the engineer stated from his initial inspection. He said we could benefit from a more detailed inspection where they take samples and analyze it.

First option was to jackhammer out the bad parts and see if the rebar was effected. If the rebar was affected only a bit we could replace that part with new metal and repour. (5000k)

If the rebar was more affected and we could drill further and do more plugs. But steal beams would be needed. I suggested 5 beams on each side of the large concrete beem in the middle. He said this concrete beem had two small cracks in it running accross the beam, but there had been no sagging so it should be fine. (10-15k)

We calculated in a higher amount to make sure we cover our tracks.

Does anyone know of any good reliable people that can fix somethign like this. This comes from a person who does not trust his mechanic.

Billie
 
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Old 08-25-12, 07:24 PM
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I sent you a PM with the name of a reputable concrete repair outfit. Didn't think the forum police would let me post it here, as it could be considered "advertising." The firm is a big one, with a good international reputation (but not afraid to work on smaller residential projects such as yours). Their specialties are both concrete repair and corrosion protection.

P.S. Maybe you just haven't found the right mechanic yet. I'm lucky to have a local "keeper"--he's extremely honest, with reasonable rates and no "Keep Out" signs hanging above the shop doors.
 
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