Browse Forums General Discussion Re: Warning about suggested repairs of slab heave 21Jun 23, 2012 10:31 am So what are you saying causes the heave when a concrete path is present around the entire house? I really can't see a 900mm path stopping a great deal of moisture. If it was so simple why don't builders save a lot of heart ache on all sides and pour a path around the house? Would add very little cost, especially on a class P site where added measures are needed. Re: Warning about suggested repairs of slab heave 22Jun 24, 2012 10:34 am The idea is that the apron should graded away from the slab to direct excess moisture away from the area immediately adjacent to the footings - if water cannot flow horizontally then it eventually seeps down vertically and this will not affect the footings as much with a graded apron present as that vertical water seepage happen further away (this is mitigated further by ag drainage and the presence of water leaching vegetation such as lawn). It is the swelling of the clay-based subsoil that makes the footings themselves move up and down, thus causing slab heave. A weaker slab will not be as stiff and flex more (hence the heave in the corner that BE mentioned) but if the slab is stiff enough to not flex as much if one corner is exposed to excessive moisture around the footings then the whole house will tilt. Your question is a good one though as it is a government (CSIRO) recommendation to do an apron around the house but no builder does it - probably just as much because not all customers don't want an "ugly" ~1m concrete path around their house that will cost them a tidy sum as much as anything else, but also because customers generally speaking already have a baseline impression that builders are ripping them off for things they don't need or shouldn't have to pay (as much) for (I doubt there's ever been anyone who hasn't at some point thought they were getting ripped off on something in a build). Some people apparently have nothing better to do than comment on other people's sigs. Re: Warning about suggested repairs of slab heave 23Jun 24, 2012 11:39 am The concrete path might work on a completely flat block but what about areas on a grade? The sub surface moisture will flow straight under the path from other areas of catchment. Ag drains will catch some of this but not all. Re: Warning about suggested repairs of slab heave 24Jun 24, 2012 3:50 pm If there is such a grade then the run-off will take the path of least resistance (ie. along the surface down the slope) - it generally only soaks into the ground when it doesn't have anywhere to move horizontally (ie. it is ponding) and the ag drainage and run-off handling system for the block would need to be designed to cope with such issues to redirect run-off away from the footings. If a builder/landscaper/owner allows water pond against the footings for any house (regardless of slope) then they are exposing the house itself to the risk of slab heave. The slab/footings themselves would also need to be more heavily engineered to cope with the potentially higher shear loads, but this is to stop the house from slipping down the slope and still wont prevent slab heave if excess moisture gets into the footings for areas that have a soil profile that is predominantly clay. Some people apparently have nothing better to do than comment on other people's sigs. Re: Warning about suggested repairs of slab heave 25Jul 01, 2012 11:50 am To the OP, is it possible to get details of the recommended fixes? We are having heaving issues after just 8 weeks of building being completed...while our builder has admitted there is a major issue and have their engineers coming out we need this fixed properly. We will be engaging our own independant guys to make sure what our builder says matches what others are saying. Cheers Re: Warning about suggested repairs of slab heave 26Jul 01, 2012 12:46 pm Hi weezaway I am still having trouble comprehending that Building Commission has actually got something right. That goes against all I have come across over the last eight years and countless heartache for my customers. I did ask for the name of their engineer because it is worth knowing but so far you have not responded. Keep in mind that anything Building Commission does is not binding on the builder and is unenforcible. It is possible that the builder will tell you all you want to hear and forget everything once you have turned your back. How is the slab heave going to be fixed? How are slab levels going to be brought back to required tolerances? I suspect they sold you Clayton's fix. 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 28Jul 02, 2012 10:33 am Hi Lex Clayton's is a non alcoholic drink, bottled up, coloured, and marketed to look and taste like a spirit. It's advertised as "the drink, when you are not having a drink" It's a pretender. Consequently clayton's fix is a fix when you are not having a fix. In other words you are hoodwinked into thinking defects are going to be fixed when in reality there is no chance in hell of that happening. Engineers on the other hand prefer "Jack Daniels", a good excuse to do nothing( the job of ageing whiskey is to do nothing). They will tell you "do nothing for 18 months then foundations will stabilise and everything will be OK. If you believe in fairies you can follow what they say. It's more likely you will become become disillusioned, sick and will give up. Just the result they want. No I am not being negative it's just I have seen it many times and have many more on my books.If you don't believe me here is yesterday's email from one of my customers: Hi Branko, Just in reply to your 2 emails, where do we go from here? If there is no fix and there is negligence should we be employing a building solicitor? Given the structural issues it will mean that we cannot sell the property without full disclosure, so we are stuck with 300k of worthless crap. I have a wife in tears who is stressed out and just wants answers, we just do not know where to go. As far as I am concerned if a slab problem cannot be resolved, the entire house should be demolished and rebuilt… 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 29Jul 02, 2012 11:37 am I have lifted this from BC web site Media Statement From the Building Commission The Building Commission continues to investigate, and is working with the industry, to determine the extent and cause of the slab heave issues in isolated parts of the western suburbs of Melbourne. Volume builders are responding to the issue and working closely with homeowners affected to rectify the issues. Many homes have been repaired or are in the process of repair. The slab heave issues appear to be affecting houses built around 2009 near the end of the drought. Houses built since do not seem to be experiencing this level of slab heave. Slab heave can also be the result of landscaping and the installation of drainage systems close to the home. The Building Commission will continue to work with the industry to examine the cause of the slab heave issues and encourages affected homeowners to work with their builders to rectify the situation. All houses are designed to experience some movement in the slab. It would appear that this movement has been exaggerated in some cases and indications to-date are that the effects of this are non-structural. The volume builders have assured the Building Commission that they are prepared to work with affected consumers to rectify the situation. Homeowners who believe they may be affected should contact their builder. --------------------------------- Do you believe in fairies? 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 31Jul 03, 2012 8:29 am building-expert Media Statement From the Building Commission ... Slab heave can also be the result of landscaping and the installation of drainage systems close to the home. Have they mixed up the words here?? I thought that drainage systems should be installed close, not far, from the home ... My signature is distracting people from my wise posts ... Re: Warning about suggested repairs of slab heave 32Jul 03, 2012 12:59 pm It's more than just a mix up, have look at this paragraph: The slab heave issues appear to be affecting houses built around 2009 near the end of the drought. Houses built since do not seem to be experiencing this level of slab heave. Really, what planet are they on? Fairyland 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 34Jul 04, 2012 11:49 am You stop at the garage, just make sure there is good drainage along boundary wall 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 36Jul 04, 2012 12:27 pm Sometimes there are no perfect solutions, you do the best you can. 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 37Jul 04, 2012 4:12 pm I would not entirely agree with 'building expert" - "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" The prevention of water ingress into the clay soils under or abutting the slab is the key issue to reducing slab heave with reactive soil profiles. One of the major sources of penetration can come from subsurface seepage from incorrectly backfilled service pipes into the slab (shower wastes etc) or parallel piped trenches (storm water) within close proximity of the slab edge. Surface water (rain or garden watering), which an apron around the dwelling could help to offset, can be a contributing off-setting factor but in many cases this would not provide a solution. There needs to be site specific documentation from the slab designer taking into account water table levels logged in the geo report, site slope etc as to the required preventative measures needed to be implemented (site specific) for the required slab performance. Peter Clarkson - AusDesign Australia www.ausdesign.com.au This information is intended to provide general information only. It does not purport to be a comprehensive advice. Re: Warning about suggested repairs of slab heave 38Jul 05, 2012 7:36 am Hi Peter Thanks for your comment, healthy disagreement is what this forum is all about, If we all agreed there would be nothing to talk about. "The prevention of water ingress into the clay soils under or abutting the slab is the key issue to reducing slab heave with reactive soil profiles."- You are spot on! "One of the major sources of penetration can come from subsurface seepage from incorrectly backfilled service pipes into the slab (shower wastes etc) or parallel piped trenches (storm water) within close proximity of the slab edge." Correct but not the only source. What about surface drainage and what about maintenance of moisture equilibrium?(isn't maintenance of moisture equilibrium around perimeter of slab on highly reactive soil essential?) "Surface water (rain or garden watering), which an apron around the dwelling could help to offset, can be a contributing off-setting factor but in many cases this would not provide a solution." This is where I disagree. Defective surface drainage can on its own be the cause of slab heave ( I have seen it many times and I have it documented and photographed. Now go back to the statutory warranties DBCA s8 (f) "If the contract states the particular purpose for which the work is required, or the result which the building owner wishes the work to achieve, so as to show that the building owner relies on the builder's skill and judgement, the builder warrants that the work and and material used in carrying out the work will be reasonably fit for that purpose or will be of such a nature and quality that they might reasonably be expected to achieve that result. Q9: In exercising skill and judgment has builder delivered reasonable fitness for purpose?" Now ask yourself a question. Would a building designer, ordinarily skilled in design of residential slabs on highly reactive foundation soils (knowing potential catastrophic damage) be expected to include all provisions to prevent water ingress around slab? The answer has to be yes or or there is negligence. In my opinion, omitting paving (or similar) around dwelling as the effective means of foundation protection and moisture content stabilisation (given relative low cost to the potential cost of catastrophic damage) does not deliver fitness for purpose and consequently is a breach of warranty. Brach of warranty is a defect, builder's(designer) liability follows. Ordinary owner has the right to expect that their new home is designed and constructed with skill and care and that it will withstand normal use in normal conditions(whether it is a highly reactive site or not). Owners are not builders. They don't have the skills to build paving and I have seen them getting it wrong countless of times. This is where builders and designers have failed (catastrophically) to deliver what is expected of them and now they are trying to hide behind SCIRO home maintenance guide. It's disgusting. I have VCAT dispute coming up on this issue with one of my clients whose home has been destroyed and look forward to proving my point. Stay tuned. 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 39Aug 27, 2012 7:12 pm Any updates? We haven't heard what the remediation will involve. I have just had an excellent structural engineer/consultant have a good look through my house, take slab levels and sample my soil. I will let you guys know what he comes up with. Re: Warning about suggested repairs of slab heave 40Sep 16, 2013 3:58 pm So 12 months on - can you please now update us on what the slab and levels are like now in your house? Did it return to the levels it was intended by making the amendments that you did? 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