concrete path "sinking" around the house...?

Hi everyone,

I have been a property investor for a while but never posted on Somersoft forum before...

I have an unusal problem with one of my properties. It is a brick veneer unit about 25 years old, and at the last inspection I noticed that the concrete path around the back of the house is sort of receding, and judging by the traces of concrete on the wall it is now about 6-7 cm down from where it was initially. It is only happenning around one corner of the house (about 4 m each way), not on all sides. The walls don't have any cracks (internal or external). I am sure it wasn't like that about 3 years ago when I was living there..:confused:

I checked with the plumber as my first thought was that the may be some water leak underneath that moves away the soil, but the plumber said there is no plumbing in that spot according to the plans. He recommends pulling up the concrete to see what happening underneath...

Has anyone had come across this type of problem and who would you contact to deal with that? And if ripping up the concrete is the only way to find out would you hire a handyman to do it or someone else?

Thanks heaps,

Ira
 
Hi everyone,

I have been a property investor for a while but never posted on Somersoft forum before...

I have an unusal problem with one of my properties. It is a brick veneer unit about 25 years old, and at the last inspection I noticed that the concrete path around the back of the house is sort of receding, and judging by the traces of concrete on the wall it is now about 6-7 cm down from where it was initially. It is only happenning around one corner of the house (about 4 m each way), not on all sides. The walls don't have any cracks (internal or external). I am sure it wasn't like that about 3 years ago when I was living there..:confused:

I checked with the plumber as my first thought was that the may be some water leak underneath that moves away the soil, but the plumber said there is no plumbing in that spot according to the plans. He recommends pulling up the concrete to see what happening underneath...

Has anyone had come across this type of problem and who would you contact to deal with that? And if ripping up the concrete is the only way to find out would you hire a handyman to do it or someone else?

Thanks heaps,

Ira
Hi
Where is the property located,could be subsidence or before ripping up concrete I would get out a good building inspector.
Macca446
 
Thank you for the reply Macca446,
The property is in Ormond ( south-east Melbourne). I was thinking about the building consultant and called one to discuss, but he said the same - pull up the concrete..

I might try calling someone else..
Thanks, Ira
 
Are there any stormwater pipes under the slab? This will often wash away the sand under the paving and cause it to subside. There have been a few similar threads (with photos too).

If all else fails, saw cut one of the affected panels of paving, that should give you a good idea.
 
Thank you Scott, I asked the plumber but the stormwater pipe is going in the opposite direction from this corner of the house. There is a sewerage pipe about 2 m away but it is on the neighbours side going along the fence, and it is 2m deep so probably unlikely to cause the problem.

Re saw cut the panel of concrete - do I need to hire a concreter to do it? sorry for the dumb question...
 
Just go on-line and look for a 'concrete cutter'.
They charge by the lineal metre. It won't take long at all if it's an external path.
You could hire the saw yourself, but they are a real handful and for the cost and time involved in hiring one, you might as well just get someone to come and do it.
Be warned, they are possibly the loudest machines ever invented.

Get onto it quickly before the problem gets worse and you end up with an underpinning issue.
 
Ahh why haven't I thought ot that myself! Thank you Scott :)!! Still clinging to the hope there is nothing wrong underneath but feel I should better be safe than sorry...
 
I don't think cutting up the pathway slab will reveal anything other than a nice view of dirt. There are a number of factors which cause subsidence and would be easily identified by a qualified structural engineer (no slab cutting required).

How serious are you about sorting out the problem? I don't mean to cause alarm, but 6-7cm movement in a path slab is quite a lot.. Better to address the problem before movement shows in the house.
 
hi vbplease, I honestly trying to sort it out as I planned to keep this property for a while - may be another 6-7 years, so don't want to get into bigger problems. I now actually emailed a structural engineer but he said "as there is not any evidence of structural problems with the house (cracks etc) it is unlikely that this would justify an engineering investigation or that one would be particularly useful. Probably best to just get the paving taken up, revealing and repairing whatever abnormality underneath is causing the problem." So yes I am worried what would be the next step after the concrete is lifted but can't get any advise other than "pull it up and see"...Very confusing...:(
 
I'm surprised an engineer would say that.. Sure if it was 20-30mm nominal movement in the path slab and no structural damage has occurred in the house. But 70mm is worth getting an engineers report imo.

If cutting up the slab you have to factor in cost to remove it, cost to reinstate it, and it's new appearance. More importantly it won't give any answers as to what the problem is.. It will just reveal normal looking soil 70mm lower than it should be.

I know a good engineer in Melbourne if you'd like a second opinion. Pm me if you're interested.

A stitch in time will save 9. Potential Patching of cracks to plasterboard and painting over, and re-pointing cracked brickwork will prob cost a tradie a few hundred each.. And be noticeable to a building inspector when selling.
 
Foundation maintenance and footing performance

Hi, just an update - had several discussions with engineer and concreters and it seems there could be several main causes for concrete subsiding at this site:
1. badly compacted soil over the sewer that runs along the fence on the neighbour's side
2. Two trees nearby were causing soil drying (cut them down now)
3. soil were not properly compacted when the concrete was laid.

According to the engineer even 70mm settlement is not uncommon...

As the concrete is now sloping towards the house wall on one side I will still have to redo it, and the quotes are coming in around $2200-$2500 mark for partial removal of the old and laying a new one :(. Plus I still need to do a soil test to check there is not much chance for the concrete to sink much more after the new one is laid. Concreters propose laying a new one on top of the old one, is this OK if there is no damage to old concrete?

I got a very informative document by CSIRO on Foundation maintenance and footings problems from the engineer I consulted, so I am attaching it for everyone as there is lots of good info. So many factors affecting the footings!

Thank you everyone for your advice!
 

Attachments

  • CSIRO Homeowners Guide BTF 18.pdf
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