Browse Forums General Discussion 1 Jul 02, 2021 2:17 pm Hi all, Recently while doing backyard renovations we noticed a small hole open up next to our slab. I dug the hole open to have a look and found a cavity under our slab. I'm a little lost on what to do from here, who to talk to etc.... Some basic info that I think would help. The house was built in 2007 in Northern Suburbs of Melb, it is a volume builders build. We are the second owners. The cavity at a rough guess would go about 1.5 meters in towards the center of the house and 2-3 meters along the back edge of the slab, (its a little hard to tell) and depth of 200-250mm deep at its deepest part. The concrete apron/walkway on the adjoining wall has also dropped away from the slab enough to fit your hand between the slab and wall. It has been mentioned to me also that it is possible a "Very Large" boulder may have been removed from the approximate spot on the property before building however in the paperwork I have its not mentioned anywhere. I guess I want to know what options I have for repair, does insurance cover any issues like this or if in the instance large rocks had been removed prior to building are the builders at all responsible before I go paying for it myself. Appreciate any advice, Thanks Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Land settlement / cavity under slab. HELLLP 2Jul 02, 2021 4:48 pm Hi James, Is there any cracking in the brick veneer or plaster inside the house? If there is not - with this level of settlement, and considering you hadn't noticed it had settled until you dug the hole, I would suggest there is not much to worry about as the raft is likely on piles. The footpath falling away is not so much an issue, but it would be worth waterproofing the gap to prevent any further water ingress. Re: Land settlement / cavity under slab. HELLLP 3Jul 02, 2021 8:35 pm Andrew1990 Hi James, Is there any cracking in the brick veneer or plaster inside the house? If there is not - with this level of settlement, and considering you hadn't noticed it had settled until you dug the hole, I would suggest there is not much to worry about as the raft is likely on piles. The footpath falling away is not so much an issue, but it would be worth waterproofing the gap to prevent any further water ingress. There's no cracking in the brick veneer that I've noticed, inside the house we have a crack in the ceiling in a nearby area but I do put that down to the nails pulling and accept that as movement, we do have other cracks in corners of walls in other spots of the house but I wouldn't say they are "Bad". This is the back of the property where I have found the problem shown in Red, there are 4 piers only at the front of the house. . Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Land settlement / cavity under slab. HELLLP 4Jul 03, 2021 10:09 am Hey jamest98 Welcome to the forum Check to see if your engineering /contour clearly show cut and fill line? Engineering notes 2. States "Remaining Fill Including Top 150mm Of Existing fill is To be Compacted With Suitable Site Excavation Equipment To Achieve a bearing Capacity 50KPa" Was the site inspected and an Engineers certificate Issued? BTW the movement and cracking will get worse overtime, unfortunately you are now outside of the structural warranty period. Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Land settlement / cavity under slab. HELLLP 5Jul 06, 2021 8:10 pm I had a similar issue a few years back on my house which was about 12 years old at the time. We had a busted pipe that directing water under the slab. I contacted a structural engineer who came out and made some recommendations. He suggested the whole thing be dry packed and I got some foundation repair guys in to do it. The report was close to $1000 and another $2500 to fix the slab but that was worth it for the peace of mind. Thanks for the insights, that makes perfect sense, and yeah, I will be leaning on the experience of the excavator operator entirely. 6 16147 4 5116 To me, that's what it looks like: poor backfilling and/or compaction. The width is about 1000mm maybe. That conduit in the photo is for the NBN. The water is about… 4 8042 |