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How to fix hole in concrete floor?

Please send me any advice or ideas on this as I am totally at a loss! I have a decent sized hole in the concrete floor in the corner of my bedroom where the two walls meet. I’d like to fix it but don’t know how, I’m unable to afford to get someone to fix it for me and I don’t want to delay any longer as I’m concerned that it is undermining the integrity of the walls as they are cracking. Any and all input is greatly appreciated!

it is fairly deep-I can fit a chisel into it up to the handle. In the last year or two it has worsened and a hole is starting on the other corner, and as you can see in the picture the walls appear to be separating from the concrete floor. Please help!

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MitchellMc

Welcome to the Bunnings Workshop community @daniT. It's brilliant to have you join us, and many thanks for your question about fixing a floor.

I'd have to say that this is potentially out of the realm of DIY, and the structure and slab need to be assessed by a professional. Do you happen to have home insurance? I'd imagine an assessment of the structural integrity of the building could potentially be covered under that.

There's no D.I.Y. fix that I can think of that I could possibly recommend. I would imagine that the foundation and wall would need to be shored up by injecting some type of high-compression cement that's under pressure into the void. I'd recommend against doing this yourself, as by filling the hole you could restrict access to someone that needs to assess the site.

Let me ask a few of our knowledgeable members @TedBear, @Dave-1 and @MrSober for their thoughts.

Please let me know if you have any questions.

Mitchell

daniT

Thank you for your reply, unfortunately I don’t have insurance at the moment but I have looked into it and from what I can see it wouldn’t cover this anyway. I won’t be in a position to afford to do anything about it myself for a while so I’m worried about the damage becoming worse in the meantime. Can you think of anything I can do in the interim to perhaps shore up the support or prevent it from continuing to degrade? Some sort of temporary stop gap I could use?

MrSober

As mentioned I really think this would be something you wouldn't want to try and DIY, unfortunately appears to be one of those times you really need to contact a professional.

The only thing is maybe if you can try and track down what might be causing the issue in the first place and try to remedy that might stop if from getting worse? Is this corner one that can be seen from the outside of the house?

TedBear

Hi @daniT , I have to agree with @MitchellMc and @MrSober that this looks pretty serious and needs professional input, as it is putting your home at risk. Something must be undermining the walls and floor, such as an underground stream or water leak, which could explain the gradual progressiveness of the problem. Putting something in the hole would only be masking the symptom of the problem and not solving anything. It would be best examined and assessed while the holes are fully accessible. I understand that you may not want to spend money on it, but at this stage of the damage, you really can't afford not to.

daniT

I checked the outside and lifted some pavers, there was damp sand underneath and I wonder if it could possibly be a slow sewerage leak? In that area/ that side of the house there’s issues with cracks in walls, the hot water tank sinking down and therefore coming away from the wall. There’s also extensive ants nesting under the concrete under the garage (which shares a wall with that bedroom) and I’ve found a root from a tree next door going under there too. I’ve been told it could also be due to the builder rushing and not letting the pad dry properly. I am aware of the severity of this and quite afraid to be honest but simply cannot afford to have it repaired by a professional, especially as it could be any number of issues for the cause. Thanks so much for taking the time to look at this I truly appreciate it. I’ll have to find a way to get an assessment done. Thanks again

MitchellMc

Hi @daniT,

Look for companies that specialise in foundation stabilisation and see if any will do a free quote for works. That will likely give you a good idea of what the issue is and possible remedies for the situation.

I don't believe any of the issues you've listed would cause a slab to deteriorate and drop away like that. It would be more like a severe mains water leak that has washed away the soil/substrate under the slab. However, even then, I'm surprised to see the slab degrade and fall away too.

Mitchell

Dave-1

Good morning @daniT

😕 to your concrete. It looks like the concrete is sandy even? I do agree with the other comments that the problem is probarly above a diy level. Just filling the hole in wont fix something that has been getting worse. (I have this same type of issue around my pool I think)

I would be finding some foundation repair people. You say the hole has been worsening and that tends to make me think that the concrete isnt exactly concrete as I have never seen it eat away like that unless its what I call "sandy" My old path was a sandy type and it was solidish, but it wasnt strong as concrete normally is and had a sandy texture to it.

Foundations are a pain.

Dave

daniT

It appears to be corroding in the affected area, everywhere else on the floor the concrete feels ok. That corner just flakes away with very little effort

daniT

The house was built in 2008 so although I know little to nothing about this I’m surprised as well. The other week the water corp was out front repairing damage to the water main-the problem had been noticed and marked with spray paint on the footpath but there was some mix up where it had been marked off as having been fixed despite it not having repairs done on it. Should I contact the water corp?

daniT

this is a picture of the exterior of the area-and one of the cracks happening at almost ceiling level of the same corner as the hole

MitchellMc

You could contact the water corp, but I can't imagine the work or leak would have anything to do with the deterioration of your slab @daniT. It's more likely that the concrete in this area didn't have enough cement in it, or there was too much water. This leads to concrete that disintegrates. It's also not disappearing into nowhere, so there must be some type of void underneath the slab. This void could have potentially been caused by a severe water leak if it was in this vicinity.

Mitchell

daniT

Thanks so much for your help! I did have a look into the hole with one of those little cameras on a flexible bending wire-I just kept getting pushed up and into the cavity between the bricks of the wall

TedBear

Hi @daniT

I would definitely contact the water board, but don't initially take your problem to them.... they will likely go into self-protect mode and tell you nothing.

Just inquire as to what they were doing and what they found - and ask if there is anything that you should be concerned about on your property as a result.

They should then be honest with you as it would be a severe neglect of care for them to lie or even sidestep such a question.

Best inquire by email, since then you will get a written response - the spoken word is useless, while written responses will be more carefully crafted since they could be used in a court if the Water Authority were found to be either liable for your damage or to have lied to you in a way that resulted in you being uninformed about what the correct action might be.

If their work was something minor then they will tell you, so at least that line of inquiry can be put to rest.

I also agree that you should see if you can get a free quote (or two), so that you may get some better ideas of what you are dealing with before proceeding, in whatever way you decide to.

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