Browse Forums General Discussion 1 Jun 06, 2012 6:52 pm We built a house in Melbourne's western suburbs with one of the large volume builders and we moved into it 15 months ago. In the past 3 months we have experienced major cracks in walls, skirting boards and cornices splitting at the joins, architraves splitting from the walls and ceilings, bowing of the ceiling (visible with the naked eye) and doors jamming. These problems have occurred in every room of the house. We contacted the builder who told us to put in a 1 metre footpath around the entire house, and build a retaining wall to stabilize the foundation, and this was to be done at our expense. Because of their unclear and contradictory (and expensive) suggestions that they expected us to do, we sought advice from consumer affairs, who agreed we had a complaint worth investigating. Mediation took place at my house with myself, the warranty/maintenance manager from the builder, a civil engineer from the building commission and a senior conciliator from Consumer Affairs. The engineer made it clear that the builder was required to be responsible for the stability of the slab, not us. All of the repairs required have been agreed to by the builder including re-landscaping of the garden to guarantee water will drain away from the house. The engineer advised that neither a footpath around the house or a retaining wall would be required to fix the problem. I guess my point is that without the attendance of Consumer Affairs, we could have spent literally thousands of $$ following incorrect and unnecessary solutions that were offered by the builder. Problems that we've tried to get them to address since the house was built are also going to be attended to, and this wouldn't have happened without the independent building inspection the weight of the engineer's findings and the presence of consumer affairs. Finally, the builder is listening and has agreed to everything, with completion of all repairs to be in 60 days. The slab then needs 12 months to settle once new drainage is done, and then they have agreed to re-repair any cracks that open up because of the slab settling. I am happy to talk to anyone about how this resolution came about. We have been so stressed about the situation of our house, and I imagine anyone in this area experiencing slab heave is going through similar stress. Re: Warning about suggested repairs of slab heave 2Jun 07, 2012 12:06 pm Hi Weezaway Can I ask that how long the slab was cured for? We are building at the moment or at least about to sign off on the plans and our builder are trying to convince us that the concrete only needs to cure for 1 day.. and reading about what has happened to you, I wonder if it has anything to do with the slab..... I'm really happy that you have finally got the result you were after.... Re: Warning about suggested repairs of slab heave 3Jun 07, 2012 1:05 pm Slab heave has nothing to do with the curing of the slab itself - rather it has to do with excessive moisture levels causing the earth beneath the footings to swell up and make the slab flex. As for your curing issue, [deleted misinformation] - the "start" the builder is referring to will more than likely only be assembling the frames and putting them in place (propped up initially instead of being bolted into the slab), which wont really affect the slab itself. It wouldn't hurt to let the slab cure for a few days or even a week or so, even though no excessive weight is going to be placed upon the slab until later on when the bricks and especially the tiles go up (if you have a tiled roof that is). (apologies for the brain fade there) Some people apparently have nothing better to do than comment on other people's sigs. Re: Warning about suggested repairs of slab heave 4Jun 07, 2012 1:38 pm Out of interest, what class slab was the home built on? Building a Delta 21 at Craigieburn - http://homeofzero.blogspot.com.au/ Deposit: 26/02. Contract: 22/05. Settlement: 29/05. Site start: 18/10. Re: Warning about suggested repairs of slab heave 5Jun 07, 2012 1:58 pm It is refreshing to see that for once Building Commission got something right,about 8 years too late for many people. Full marks to the engineer. What is the name? It's worth knowing. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Warning about suggested repairs of slab heave 7Jun 07, 2012 11:07 pm Aitch72 Hi Weezaway Can I ask that how long the slab was cured for? We are building at the moment or at least about to sign off on the plans and our builder are trying to convince us that the concrete only needs to cure for 1 day.. and reading about what has happened to you, I wonder if it has anything to do with the slab..... I'm really happy that you have finally got the result you were after.... Hi there...our slab was poured 30 Sep and the full frame was up by the morning of 05Oct - there was a weekend in between too. I don't know if this had an impact on slab heave or not. Re: Warning about suggested repairs of slab heave 9Jun 08, 2012 9:06 am Wow, what a great and useful thread! You don't often see such a nice summary of problems (and emotion-free) of such a critical issue. I think this is a rarely altruistic gesture, especially after everything that you've been through. I hope the fixes go smoothly and they do fix it properly. Now, could I ask about the topology of the site (levels/heights of land and the neighbouring lands) abd what kind of drainage was installed during the build and where ... etc. Did you have any large removed trees, or sand / fill / heavy clay / ??? so that the site was classed as H? Is this a single level house? What was your landscaping like? My signature is distracting people from my wise posts ... Re: Warning about suggested repairs of slab heave 10Jun 08, 2012 9:19 pm Good to hear of a result. When we had a problem (different one) Consumer Affairs told us they don't deal with building problems. Does it vary from state to state or does it just depend on whether the person you speak to on the day feels like taking on another matter? Re: Warning about suggested repairs of slab heave 11Jun 08, 2012 11:18 pm weezaway akashra Out of interest, what class slab was the home built on? H Class A volume builder built a house in the West of Melbourne on a H-class slab? :/ Yeah, uhh, well, while every site is different, the land over that side of the city is rarely truly happy with thinner slabs. Mine got the soil report that said H and went straight to P. Building a Delta 21 at Craigieburn - http://homeofzero.blogspot.com.au/ Deposit: 26/02. Contract: 22/05. Settlement: 29/05. Site start: 18/10. Re: Warning about suggested repairs of slab heave 13Jun 20, 2012 12:59 pm Quote: As for your curing issue, well concrete achieves 80% of it's maximum strength after 24 hours so it is possible to start after only a day of curing time, cmhamilton this is absolute rubbish and you really shouldn't be spreading such crap on a topic that involves slab movement. It takes a lot longer to reach 80% strength and your lucky for it to even reach 80% if it's only air cured. Its probably under 10% strength at 24 hours. 7 days and its still under 50% strength. Have a look at the diagram below and take note of the x axis I doubt any of the major builders water cure their slabs, so they never actually reach their designed strength which is a worry. Re: Warning about suggested repairs of slab heave 15Jun 20, 2012 6:43 pm Hi JimmyL Would you please specify design strength of the sample tested, to me it appears to be 35 MPa and perhaps not relevant to residential slabs which are usually 20 MPa Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Warning about suggested repairs of slab heave 16Jun 20, 2012 9:05 pm JimmyL cmhamilton this is absolute rubbish and you really shouldn't be spreading such crap on a topic that involves slab movement. It takes a lot longer to reach 80% strength and your lucky for it to even reach 80% if it's only air cured. Its probably under 10% strength at 24 hours. 7 days and its still under 50% strength. Have a look at the diagram below and take note of the x axis Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ I doubt any of the major builders water cure their slabs, so they never actually reach their designed strength which is a worry. You're absolutely right, I had a total brain fade there (mixed up "safe to walk on" with compressive strength) - not sure what I was thinking (obviously not much at that point in time). As for your percentages, well that depends on the concrete mix and whether any chemical treatments are applied to the slab to prevent excess drying out of the slab surface. You also need to factor in that the slab itself isn't going to be under any real sort of excessive load for at least 3-4 weeks after the pour (when the tiles and then bricks are laid), by which time the slab will have had time to cure further. Still I apologise for the misinformation - just a bit of a facepalm moment... Some people apparently have nothing better to do than comment on other people's sigs. Re: Warning about suggested repairs of slab heave 17Jun 22, 2012 1:22 pm Sorry i cannot find the link but you can just google 'concrete cure' and have a look at various articles. Air drying is not really a good way of curing the slab (especially in warmer weather and direct sunlight) and some of the smaller builders will water cure but building a small dam on the slab and flooding with water. I'm not saying this is the reason for houses moving but on highly reactive P class soils where an engineer has designed a slab specifically for the site his calculations would be based on a certain % of the strength being reached. Re: Warning about suggested repairs of slab heave 18Jun 22, 2012 10:46 pm You are right JimmyL concrete strength has nothing to do with slab movement. For the record in over 40 years of building I have not come across concrete strength failure. It's always either defective design or poor workmanship or both. The only reason slabs move is because of foundation instability caused by changing moisture content of reactive soil from poor drainage, flooding from leaking pipes or interference from tree roots. Slabs on sand, rock or stable soil will not move. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Warning about suggested repairs of slab heave 19Jun 22, 2012 10:59 pm Quote: You are right JimmyL concrete strength has nothing to do with slab movement. For the record in over 40 years of building I have not come across concrete strength failure. It's always either defective design or poor workmanship or both. How do you differentiate between them? So if a slab was designed to be half as strong as it should you would not expect it to affect the movement? Slabs are not 100% rigid and bend and warp just like anything else. Surely you would want a slab to reach its designed strength and be as rigid as possible unlike my house where one side has lifted a great deal compare with the other. I'm not arguing but you have just stated that the strength of the slab has no impact on movement. Re: Warning about suggested repairs of slab heave 20Jun 23, 2012 9:10 am Yes, if the concrete is under strength slab stiffness will be reduced but in foundation heave it will make no real difference. I have seen slabs with heaved corner or a side and slabs with tilt across the whole house. It does not matter how strong the concrete is or how reactive the soil is because if there is no change in moisture content there will be no movement. This is why I believe that on reactive soils (among other precautions) a concrete apron around home is a must as a part of the design and cannot be an optional extra, or be left out for the owner to do. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Does anyone have a suggestion for a good hydronic in slab heating speacialist who may be able to help me with an existing system and wether or not it may need a seperator… 0 3448 Hi all, Trying to workout the minimum stepdown required between slab for my house and the outdoor alfresco area. Garage is 100mm lower than rest of the house and plan was… 0 3655 Thanks for the insights, that makes perfect sense, and yeah, I will be leaning on the experience of the excavator operator entirely. 6 11043 |