Slab and concrete block potential repair

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Old 03-17-13, 08:43 PM
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Slab and concrete block potential repair

We just had a home inspection on a house we are looking at buying. The house is somewhat of a fixer upper, and we know there will be stuff we need to take care of as we live there. There was one item on the inspection that left a little concern in my mind.

The house has an attached add-on garage on the back of the house. The garage is on a concrete slab. The walls of the garage have a few rows of concrete blocks directly on top of the slab. The inspector dug down under the slab to check for footings, and said the he couldn't find them. He did say that his screw driver that the stuck down there was only 16" long, and he wasn't sure if it was quite long enough to reach. But he isn't sure if there is a footing or not. He recommended that we have a contractor come in and dig under the slab to check for footing.

He also said that he is not sure if the concrete blocks were secured to the slab when they laid. He noticed one area where the concrete blocks were out a little bit from the rest of the wall, as if they had shifted on top of the slab.

Obviously, if there is no footing, and if the concrete blocks were not in place, there could be structural issues with the garage addition. My question is, what kind of a job would it be to repair those issues. We want to have the current owners fix the issue for us, but who knows, if they put their foot down, we may end up having to do it. Even if they do it, I would still like to know what to expect to be done for a repair.

I imaging having to go around the entire slab and dig under the edges to pour a footing under the slab. As far as securing the row of cinder blocks. Would you just remove the blocks (bottom block, and then the two blocks above it), drill a hole to install rebar into the slab. Reinstall first block and fill area around rebar with concrete to secure the block. Then reinstall the two blocks back in place above it? Would there be structural issues if you went one block set at a time around the garage?

Just looking for some insight on this.
 
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Old 03-17-13, 09:10 PM
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Here is very common here for an attached to be built on a strip footing with a block stem wall sicking 8" or so higher the planned maximum floor elevation with the garage wall bearing on the stem walls. Later, a floating floor slab is poured and sloped for the desired drainage - Normally to the overhead door, but in some cases to location in the center of the garage. The slab is supported by a soil under it and is not connected in any way to the walls.

There are several reasons for this:

1. The slightly taller stem wall allows the wood framing and siding to be the required 6" above grade.

2. A slightly higher garage door may be framed and the rest of the garage can use standard lengh framing lumber. - The result is a slightly higher ceiling in the garage and the door can accommodate taller vehicles (some vans or cars/trucks with some racks.

3. The combination of a properly sloping floor and block around the slab makes much easier to clean, especially any debris from rain and winters.

Dick
 
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Old 03-18-13, 06:16 AM
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How long ago was the garage built? If it's new, I'd check further [at the permit office too] if it's been there a long time with no issues - I wouldn't expect any in the future.
 
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Old 03-18-13, 10:37 AM
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The house was built in 68, the garage appears quite a bit newer then that. Based on the quality of the other work in the house, I doubt that a permit was pulled for the garage. But it is worth looking into.
 
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Old 03-18-13, 11:58 AM
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Not sure I agree with your method of replacing concrete blocks supporting the walls above them. Once a doweled rebar is in place (assuming it extends up through all of the courses), there will not be clearance to slide in the blocks. If the blocks are indeed loose and no longer effectively mortared in place, a thorough tuck-pointing job by experienced masons would be a way to go. Either that, or get a local foundation repair outfit to give you a quote for what they think the best repair method should be. And make sure to deduct that number from your offering price.

It's a bad practice to allow sellers to make any fixes, especially potentially serious ones like this. They'll just have their cousin Vinnie come over and spend 20 minutes dabbing some surface mortar on, and say "it's all taken care of."
 
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Old 03-18-13, 12:54 PM
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I don't know what the proper fix was, so feel free to tear my process apart. I was just trying to understand what the proper fix would be so I know.

I would want the seller to pay us so we could bring in someone and have it fixed the right way. Lowering the price doesn't really help us pay for the repair. The selling paying for it at closing (based on a quote) would be ideal.
 
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Old 03-18-13, 02:56 PM
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It sounds like the home inspector was not very thorough and was not equipped to make a definite decision. Telling you go to a contractor is a mistake because the proper answer for you was to direct you to an engineer that works in your interest, instead of try to get another job to attempt. Very often the good, tough home inspectors have higher rates that sellers will gladly pay to be ready and avoid last minute price negotiations. Was the inspector referred to you by a Realtor?

Digging down along exterior of the garage or probing with a rebar under the exterior will tell you if there is a foundation under the slab. - Never know what kind of details are used on additions, especially is different regions.

Do not allow the owner of an existing "fixer-upper" do the repairs. Determine what the corrective costs (if any) are and make your buying price reflect any repairs to be made.

When I did home inspections, I rarely worked for buyers, but for sellers willing to pay more but they wanted a clean closing and not get caught in last minute negotiations the day before closing.

Dick
 

Last edited by Concretemasonry; 03-18-13 at 02:57 PM. Reason: Added name
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Old 03-18-13, 03:37 PM
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The home inspector was very thorough. The home inspection was roughly 5 hours long, and he was not referred to us from either party's realtor. We found him based on the reccomendations of others and positive reviews. He dug down next to the foundation, and he had a 16 inch long screwdriver that he was using to feel for the footer and he could not find it. He said he could feel the side of the slab, and then where it mushroomed out a bit, but could not feel anything beneath the area where it mushroomed out. Further investigation would have required him to dig a much wider and deeper hole.

His report suggested that the problem be verified by a qualified contractor or structural engineer in his report.
 
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