SaveH2O
The VBA cannot ignore an expert report.
I can tell you they did
Browse Forums General Discussion Re: Slab Heave Cause? 41Aug 02, 2018 6:28 pm SaveH2O The VBA cannot ignore an expert report. I can tell you they did Re: Slab Heave Cause? 42Aug 02, 2018 7:49 pm And the report stated that the slab had heaved? 3in1 Supadiverta. Rainwater Harvesting Best Practice using syphonic drainage. Cleaner Neater Smarter Cheaper Supa Gutter Pumper. A low cost syphonic eaves gutter overflow solution. Re: Slab Heave Cause? 44Aug 02, 2018 8:52 pm FirstHome builder25 I hope this helps you. This is just my opinion from the limited info you have posted and photos you have provided with my knowledge of your estate and the soil conditions there around the time of your house construction. Your soil profile is probably the worst scenario for slab heave.Higly reactive dry fill over highly reactive clay.The problem with this is that moisture gets trapped in the fill layer by the relatively less permeable undrlying natural highly reactive clay layer.This causes the fill layer to get saturated and swell fairly quickly even during construction.The natural layer below will get wet and swell also but at a slower rate. The loads put on the slab by materials used being light weight cladding and metal roof mean there is vitually no weight resistance to slab heave.The builder by overpouring the footings shown in the photos also has decrease the load on each perimeter beam footing. The builder has not complied with the standards by grading the ground away from the slab.The engineers drawings will include drainage recommendations and design because it is a highly reactive site.Going by the photos, the drainage design and recommendations are unlikley to have been followed.You should check the drawings. The builder by not having the downpipes attached i(seen in your photos) or temporary downpipes installed during construction again has not complied with AS2870 by allowing water to pond against the footing. The slab will not return to it’s original level as heaving up to 62mm bends the reo and cracks the slab on the underside.Once the reo is bend and stretched it will be permanetly be in a dish shape. I have seen slabs with less than 20-30mm return to close to their original level but not exactly.The soil will never return to the pre construction drought levels again there will always be some soil volume increase compared to the original pre construction drought dry moisture condtions. The good news is by putting a correctly constructed concrete path around the perimeter of your house you may have stopped the continued saturation of the highly reactive fill layer. Your limited test holes indicate that it maybe working as the soil is no longer saturated.If that is the case then you should monitor the slab floor levels for at least the next 12 months or so to see if the slab has stabilised.This should be your main aim if you want to stay there or not persue the builder. Will slab heave come back to you in the future?It is unlikely as now the swelling clay fill is in a drying phase if your borehole moisture description is correct.The first swelling phase of highly reactive fill is the largest so subsquent swelling (even if it does get that wet again)of this fill will be less. I have seen lots of slabs with gaps formed under the slab as the soil dries and shrinks down with the slab is permanetly bent up on the perimeter. The vast majority of your heave probably has come from the original dry conditons combined with the builders non compliance with the standards.There always many other factors but these two will be the most inportant. As SaveH20 has suggested you need a good Geotech to investigate.At the very least continue to do floor level surveys. Re: Slab Heave Cause? 45Aug 03, 2018 11:14 am There is no good news and there are no good options 1 The home is severely damaged by slab heave and most probably cannot be fixed and returned to acceptable tolerances 2 The engineer you hired and the testing you have done did not produce a credible evidence against the builder. (not that there isn't any) 3 Hiring another engineer? Probable waste of money. 3 On the face of it it seems that the builder is at fault because of lack of care in managing roof and site drainage during construction. 4 VBA wont do anything Your options 1 Lump it! 2 Sell, hoping purchaser is too stingy or stupid not to get competent pre purchase inspections (you may be in luck, there is plenty of them around) 3 Take on the builder in VCAT VCAT has in the past ordered demolition and reconstruction of homes damaged by slab heave 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: Slab Heave Cause? 46Aug 06, 2018 5:03 pm building-expert There is no good news and there are no good options 1 The home is severely damaged by slab heave and most probably cannot be fixed and returned to acceptable tolerances 2 The engineer you hired and the testing you have done did not produce a credible evidence against the builder. (not that there isn't any) 3 Hiring another engineer? Probable waste of money. 3 On the face of it it seems that the builder is at fault because of lack of care in managing roof and site drainage during construction. 4 VBA wont do anything Your options 1 Lump it! 2 Sell, hoping purchaser is too stingy or stupid not to get competent pre purchase inspections (you may be in luck, there is plenty of them around) 3 Take on the builder in VCAT VCAT has in the past ordered demolition and reconstruction of homes damaged by slab heave Question. general does bored piers help stop slab heave? I don't see how? if water gets under slab with clay soil it will expand and the piers will it help? Re: Slab Heave Cause? 47Aug 06, 2018 5:20 pm MyFirst building-expert There is no good news and there are no good options 1 The home is severely damaged by slab heave and most probably cannot be fixed and returned to acceptable tolerances 2 The engineer you hired and the testing you have done did not produce a credible evidence against the builder. (not that there isn't any) 3 Hiring another engineer? Probable waste of money. 3 On the face of it it seems that the builder is at fault because of lack of care in managing roof and site drainage during construction. 4 VBA wont do anything Your options 1 Lump it! 2 Sell, hoping purchaser is too stingy or stupid not to get competent pre purchase inspections (you may be in luck, there is plenty of them around) 3 Take on the builder in VCAT VCAT has in the past ordered demolition and reconstruction of homes damaged by slab heave Question. general does bored piers help stop slab heave? I don't see how? if water gets under slab with clay soil it will expand and the piers will it help? No I have seem many slabs on piers heave off the piers.The bored concrete piers are not connected in general to the slab. Screw piles are different but you need a void formed under the slab and the slab needs to be fully suspended between piers. This way there is room for the clay to swell without putting pressure on the slab. Re: Slab Heave Cause? 48Aug 06, 2018 5:25 pm insider MyFirst building-expert There is no good news and there are no good options 1 The home is severely damaged by slab heave and most probably cannot be fixed and returned to acceptable tolerances 2 The engineer you hired and the testing you have done did not produce a credible evidence against the builder. (not that there isn't any) 3 Hiring another engineer? Probable waste of money. 3 On the face of it it seems that the builder is at fault because of lack of care in managing roof and site drainage during construction. 4 VBA wont do anything Your options 1 Lump it! 2 Sell, hoping purchaser is too stingy or stupid not to get competent pre purchase inspections (you may be in luck, there is plenty of them around) 3 Take on the builder in VCAT VCAT has in the past ordered demolition and reconstruction of homes damaged by slab heave Question. general does bored piers help stop slab heave? I don't see how? if water gets under slab with clay soil it will expand and the piers will it help? No I have seem many slabs on piers heave off the piers.The bored concrete piers are not connected in general to the slab. Screw piles are different but you need a void formed under the slab and the slab needs to be fully suspended between piers. This way there is room for the clay to swell without putting pressure on the slab. Hmm, why are so many of us paying for like 30-60 piers for new houses these days? Sigh. Unecessary costs? I'm building with small builder and using waffle slab. At that time I didn't make a big deal since I thought that the volume builders are building really huge houses with waffle slab. Surely that's ok. if I could turn back time probably I would have ask for a raft slab and pay a more for it. I'm sure my builder does that since he even build houses on Stumps and slopes. Anyway, now just have to be mindful the keep the soil are graded away from the house etc etc. Re: Slab Heave Cause? 49Aug 06, 2018 5:26 pm insider MyFirst building-expert There is no good news and there are no good options 1 The home is severely damaged by slab heave and most probably cannot be fixed and returned to acceptable tolerances 2 The engineer you hired and the testing you have done did not produce a credible evidence against the builder. (not that there isn't any) 3 Hiring another engineer? Probable waste of money. 3 On the face of it it seems that the builder is at fault because of lack of care in managing roof and site drainage during construction. 4 VBA wont do anything Your options 1 Lump it! 2 Sell, hoping purchaser is too stingy or stupid not to get competent pre purchase inspections (you may be in luck, there is plenty of them around) 3 Take on the builder in VCAT VCAT has in the past ordered demolition and reconstruction of homes damaged by slab heave Question. general does bored piers help stop slab heave? I don't see how? if water gets under slab with clay soil it will expand and the piers will it help? No I have seem many slabs on piers heave off the piers.The bored concrete piers are not connected in general to the slab. Screw piles are different but you need a void formed under the slab and the slab needs to be fully suspended between piers. This way there is room for the clay to swell without putting pressure on the slab. So waffle slab on piers still worse than traditional in ground raft slab on piers? Does the fact that waffle slab typically places the weight exclusively around the perimeter of the house footing mean it's easier to heave in the centre of the house compared to in ground raft where internal weight bearing walls mean the weight is more eventually distributed throughout the slab? Re: Slab Heave Cause? 50Aug 06, 2018 5:27 pm MyFirst Hmm, why are so many of us paying for like 30-60 piers for new houses these days? Sigh. Unecessary costs? I'm building with small builder and using waffle slab. At that time I didn't make a big deal since I thought that the volume builders are building really huge houses with waffle slab. Surely that's ok. if I could turn back time probably I would have ask for a raft slab and pay a more for it. I'm sure my builder does that since he even build houses on Stumps and slopes. Anyway, now just have to be mindful the keep the soil are graded away from the house etc etc. Piers will protect you from soil subsidence/settlement I would have thought where clay soil shrinks due to lower than normal moisture or sinks due to excessive pressure from the house. It just doesn't protect you from soil heave where higher than normal moisture is encountered and clay soil expands under the house. Bearers and Joists still the way to go if you want a peace of mind, the alternative is a fully suspended concrete slab, but I would imagine that costs a lot of money. Re: Slab Heave Cause? 51Aug 06, 2018 5:32 pm [quote defaultattr=""] Piers will protect you from soil subsidence/settlement I would have thought where clay soil shrinks due to lower than normal moisture or sinks due to excessive pressure from the house. It just doesn't protect you from soil heave where higher than normal moisture is encountered and clay soil expands under the house.[/quote] So in this case when building waffle slab it should be build on rainy season? Where the soil has been heave with all the extra moisture? Re: Slab Heave Cause? 52Aug 06, 2018 5:36 pm MyFirst So in this case when building waffle slab it should be build on rainy season? Where the soil has been heave with all the extra moisture? Would make sense to me but get insider to confirm. Still it has all to do with cost. Basically waffle slab is the cheapest foundation type out there but the one with the least margin of error. Everything else cost more. A in ground raft slab takes longer and gives you no certainty of exactly how much concrete you end up using. Bearers and joists cost more again especially with the mega sized homes people demand. So I guess the construction industry in an effort to meet consumer's high expectations for house finish by cutting the house footing margin of error to the bone. Mind you house footing design isn't part of your contract, on the performance level is. I found that out the hard way. Re: Slab Heave Cause? 53Aug 06, 2018 5:45 pm MyFirst Quote: Piers will protect you from soil subsidence/settlement I would have thought where clay soil shrinks due to lower than normal moisture or sinks due to excessive pressure from the house. It just doesn't protect you from soil heave where higher than normal moisture is encountered and clay soil expands under the house. So in this case when building waffle slab it should be build on rainy season? Where the soil has been heave with all the extra moisture? For example if you built during the start of the very wet period of 2010-2011 then you still could have encountered significant heave.This is because the soil moisture was incredibly dry from the drought.So it is more about the starting moisture of the soil during construction rather than the climatic conditions.They are related but there can be a lag between wet periods and wet soil moisture conditions. Really soil testing companies should be taking soil moisture tests in summer and extended dry periods this wasn't done by all companies 1997-2009, 2015-2016. Re: Slab Heave Cause? 54Aug 06, 2018 5:48 pm insider MyFirst Quote: Piers will protect you from soil subsidence/settlement I would have thought where clay soil shrinks due to lower than normal moisture or sinks due to excessive pressure from the house. It just doesn't protect you from soil heave where higher than normal moisture is encountered and clay soil expands under the house. So in this case when building waffle slab it should be build on rainy season? Where the soil has been heave with all the extra moisture? For example if you built during the start of the very wet period of 2010-2011 then you still could have encountered significant heave.This is because the soil moisture was incredibly dry from the drought.So it is more about the starting moisture of the soil during construction rather than the climatic conditions.They are related but there can be a lag between wet periods and wet soil moisture conditions. Really soil testing companies should be taking soil moisture tests in summer and extended dry periods this wasn't done by all companies 1997-2009, 2015-2016. Just out of interest. If during 2010/2011, if those houses were constructed using raft slab would it have solved a lot of heartache from slab heave. Re: Slab Heave Cause? 55Aug 06, 2018 5:53 pm MyFirst Just out of interest. If during 2010/2011, if those houses were constructed using raft slab would it have solved a lot of heartache from slab heave. Nobody knows for sure but it certainly would have been fewer and less severe defects as when AS2870-1996 came out, in ground raft was the mainstream option. Waffle pod was still in its very early days and not a lot of data was available. However, AS2870-1996 did say the standard applies to "waffle rafts" but I guess they stuffed up. One of the major changes in 2870-2011 was splitting class H into H1 and H2. In the Metricon slab heave case, the estimated Ys was 72mm. AS2870-1996 requires rounding to the nearest 5, so it was rounded down to 70mm and classified as class H. Now think about that for a minute, nature works on a continuum, not some arbitrary cut off set by a bunch of homo-sapiens. The couple got a slab designed for 40mm - 70mm. That's a WIDE range for basically a one size fits all design. I still blame the fact that 2870-1996 had a lot of data for in ground raft but very little data for waffle pod, especially in extreme weather conditions so that wasn't taken into consideration which meant a lot of people are suffering right now. Re: Slab Heave Cause? 56Aug 06, 2018 5:57 pm No I have seen raft slabs heave from that period.There may be slightly less damage but it is hard to compare directly to waffle slabs because each situation can be different as far as cause and degree of wetting etc. The reason you don't see as many raft slabs heave as waffles in that period is simply there were much more waffles built than rafts. I still prefer a raft for several reasons one being that the perimeter beam is dug into the ground providing a minor barrier to water getting under the slab. Re: Slab Heave Cause? 57Aug 06, 2018 5:58 pm insider No I have seen raft slabs heave from that period.There may be slightly less damage but it is hard to compare directly to waffle slabs because each situation can be different as far as cause and degree of wetting etc. The reason you don't see as many raft slabs heave as waffles in that period is simply there were much more waffles built than rafts. I still prefer a raft for several reasons one being that the perimeter beam is dug into the ground providing a minor barrier to water getting under the slab. Question for you insider, I see some of our SA friends still use in ground raft slabs even for budget builds, why is that? Re: Slab Heave Cause? 59Aug 06, 2018 6:11 pm Yes its ironic isn't it.They invented the waffle and now they don't use them.The reason is that they actually call site class"E" in SA so for waffles the step up is too much.With the raft "E" it can be dug in and the step up isn't a problem.Here in Vic everyone is too scared to call a site "E" as they are afraid they will lose their client to someone who calls it a "H2" and the builder can still use waffle slabs. During the drought the ground movement calculations were done as if it were normal conditions but in reality they should have been increased significantly.Therefore a lot of site should have been classified as "E" but weren't basically because builders wanted to use waffles and would take their business to someone who classified "H2 so they could keep using waffles. Re: Slab Heave Cause? 60Aug 06, 2018 6:14 pm insider Yes its ironic isn't it.They invented the waffle and now they don't use them.The reason is that they actually call site class"E" in SA so for waffles the step up is too much.With the raft "E" it can be dug in and the step up isn't a problem.Here in Vic everyone is too scared to call a site "E" as they are afraid they will lose their client to someone who calls it a "H2" and the builder can still use waffle slabs. During the drought the ground movement calculations were done as if it were normal conditions but in reality they should have been increased significantly.Therefore a lot of site should have been classified as "E" but weren't basically because builders wanted to use waffles and would take their business to someone who classified "H2 so they could keep using waffles. That's terrible. So only people in SA have brains and the rest of the states are filled with consumers with too high expectations and builders too willing to please whatever the cost? Is it the water that's special in SA or something? Firstly the ableflex that has been installed needs (manufactures specification) a sealant cap over the top, preventing water draining down between the slab and the… 3 5402 1 5030 |