Thread: Garage Pad Foundation Washout

Please take a look at the two attached photos. The area where the garage pad meets the driveway has washed out part of the concrete block foundation beneath the pad. The drainage problem has been corrected, but there's a large cavity beneath the concrete pad. I dumped a 50 lb bag of quickcrete in the hole and it didn't even start to fill up.

The house is located in Wisconsin - built in 1976. Does anyone know a recommended fix for this? More quickcrete? I was slightly concerned that there might be some type of drainage system in the garage foundation and I would disrupt that system by filling the cavity with concrete.

Thanks for any input.

CS

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Originally Posted by Carl Salamone

Please take a look at the two attached photos. The area where the garage pad meets the driveway has washed out part of the concrete block foundation beneath the pad. The drainage problem has been corrected, but there's a large cavity beneath the concrete pad. I dumped a 50 lb bag of quickcrete in the hole and it didn't even start to fill up.

The house is located in Wisconsin - built in 1976. Does anyone know a recommended fix for this? More quickcrete? I was slightly concerned that there might be some type of drainage system in the garage foundation and I would disrupt that system by filling the cavity with concrete.

Thanks for any input.

CS

Someone with a small concrete pump with fix the problem. That looks like a sink hole waiting to happen . Inject a bunch of concrete in there and be done with it. Either that or bus up the driveway and dig down to correct the grade beam loss in front of the garage and fill under the slab while you are at it. Unless you are already in the remodel or rehab phase in the home I would go with injecting the concrete with a pump.

Before I put any (more) concrete in the hole, I would want to know it's cause.
The soil could be going into a broken sewer line.

Originally Posted by Rick Cantrell

Before I put any (more) concrete in the hole, I would want to know it's cause.
The soil could be going into a broken sewer line.

From the OP


"The area where the garage pad meets the driveway has washed out part of the concrete block foundation beneath the pad. The drainage problem has been corrected, but there's a large cavity beneath the concrete pad."

Thanks for the input. Concrete pump sounds like a decent idea. I am assuming that the drainage problem originated from a downspout that was not carrying water away from the house. That said, it is just an assumption.

I would tend to think its not a sewer line just because 1) There are no drains in the garage and 2) the 4" main stack goes through the basement concrete pad and out towards the street - about 7' below the garage pad.

I was wondering if there would be some type of drainage that feeds to the basement sump pump. Was this type of thing ever standard practice?

Originally Posted by Carl Salamone

Thanks for the input. Concrete pump sounds like a decent idea. I am assuming that the drainage problem originated from a downspout that was not carrying water away from the house. That said, it is just an assumption.

I would tend to think its not a sewer line just because 1) There are no drains in the garage and 2) the 4" main stack goes through the basement concrete pad and out towards the street - about 7' below the garage pad.

I was wondering if there would be some type of drainage that feeds to the basement sump pump. Was this type of thing ever standard practice?

Ah, you ass-u-me. That is completely different. You need to have a proffesional come in and actally identify the drainage prblem or verify that you already corrected it before proceeding

Thanks all for the input.

If you can't get a camera in, rent a borascope. That could be a buried driveway drain.

Rick summed it up with "I would want to know more its cause"

You need to investigate, at least if its a minor repair then expose it, clean the surface and plaster the foundation below the slab as so not to allow water to pour into the block cells and freeze that up in your code zone.

Before you go and pump a block wall blindly with out knowing your wall structure condition, you need to saw cut the drive way corner and dig down and expose the block and brick face wall assembly below grade. Thats a point load over a garage door corner and that could be just simple neglect over years from the roof drains resulting in a break down of a CMU bond and a errosion between the block and that already thin looking garage floor slab. This could result with water running into the foundation cells. As mentioned,we dont get enough information like grade and roof info to troubleshoot.

You want to make sure you expose that surface and cure the repair correctly or your doing just what you stated, pouring 50 lbs blindly into a hole not knowing where its going. just spending time and money, so spend it wisely.

following John's suggestion, the other way would be get a plumber in with a scope to further investigate and get a video of what your dealing with. there are several ways of dealing with it and costs. find out what works best for you. a short scope might shine some light on the issue but a plumber will have the resources to do deep if needed.

You would spend $300 to $400 here in NJ to scope that, waste of time to drop a scope 3 to 4 courses of block till you hit top of footing.
saw rental $35, bags of black top $20, cement patch $5.00, shovel- hopefully in the garage.

You need to cut the driveway surface back just to bend the scope in any way. Once the asphalts up, take a couple shovels of dirt out down the block foundation which would expose something simple or structural cracks.

Carl stated drain issues, the water eroded the block after the black top settled. I would be more incline to spend money in the direction of observation and hopefully simple repair. That top course under the block should be filled solid below the garage slab threshold. It also looks like someone skim coated something on that road salted garage slab. You guys must salt the crap out of the roads like they do here in Jersey or thats one course aggregate slab surface.