Browse Forums Building A New House 1 May 27, 2009 8:24 am Hello all again, Missy the questioner here (again) I am hoping people here have been in the same situation and can put our mind at ease a little. The lot we have on hold has a lot of fill on it. Ranging from 200mm at the front to 1000mm at the rear on a 41m lot. The house will be 22m long so majority will be only in about 400-600mm of fill. Speaking to the Developer and the testing firm we know the following: - Level 1 inspection criteria for the Contractor in accordance with AS3798-2007; - Structural Fill being used; - Site cleared of topsoil to subgrade and tested (DCP and Compaction to 95%); - Each lift in 150mm layers, tested for Compaction to 95%, if it fails the area must be re rolled and re tested; - Previous stage had 120 lots in fill ranging from 0 - 1500mm and not one came in as P that I've been told. But what we were told was that, some lots came in as a P (problem) but were then re-classified as H because of the Level 1 inspections and compaction reports. What I am worried about it is if the builder does his tests and it comes as P class and they try smash us with variations. Could somebody also please explain how the who P class site but H class slab works? Do we pay for a H class slab? Our builder has given us a fixed price site cost that includes a H class slab. Am I losing sleep over nothing? What are your thoughts? All info greatly apprieiciated. Thank you soooo much.. Missy Re: Fill In Lot - Should we be stressed? 2May 27, 2009 8:33 am Hi, Our slab is class P and in the contract it shows our house requires 21 piers. Hii, I wouldnt be too concerned if the site is P class. Try tlk to others in your treet to see how much they have been charged for site costs we are building with DFH and we require a P class slab and also 21 piers at the rear of house due to fill on our block. I dont think our fill is quiet asdeep as yours but this is the breakdown of our site cost as it reads on the conract: Fall of Land: 700mm across building area: Site excavation over house and garage area. Agricultural drains to base of site cut conntected to storwater via pits. $3806 Provide Class 'P' concrete slab in accordance with the reccomendations of the soil report. in lieu of 'M' class. $5386 There was also a provisional sum of $1500 to remove the excess soil however we are removing this as we are having the excess soil pushed to the rear of the block and we will use it somewhere. Hope this helps Re: Fill In Lot - Should we be stressed? 3May 27, 2009 8:41 am I was told that a P class slab is actually a H class that requires piering. Depending on depths they need to go to and then if they find rock while doing piering it could get very expensive. A friend of my brothers bought a block of land subject to soil tests and good thing he did, he discovered that his block was part of an old dam (all old farm land) and was almost all fill and so he got out of the contract of sale and bought a different block 'A bottle of wine contains more philosophy than all the books in the world.' Louis Pasteur Vegie garden: viewtopic.php?f=19&t=27637&start=0 My Backyard Adventure Re: Fill In Lot - Should we be stressed? 5May 27, 2009 9:17 am If it has a compaction report then it should be fine! Friend of mine bought on an old dam and it was all basically fill but because it had a compaction report it was classed as a H class slab with no piers! Our block is M class but we had to cut and fill... therefore our fill was not compacted and is about 400mm deep and all they did was deepen our edge beams of our slab at the back over the fill. Although next door had m class the same as us but because they had a bigger fill with no compaction they had to put in 12 piers and i know their site costs came in under 10k 2nd build here we come in Whittlesea! https://forum.homeone.com.au/viewtopic.php?f=31&t=92617 1st Build - Henley - Cooper in Doreen! (2009) https://forum.homeone.com.au/viewtopic.php?f=31&t=17354 Re: Fill In Lot - Should we be stressed? 7May 28, 2009 9:08 pm Hi, we had a metre of fill across whole of the block! We were quoted $42k for site costs, including cut/fill, and piering!!! Needless to say we pulled out of contract and bought another block! Good luck! Re: Fill In Lot - Should we be stressed? 8Jun 06, 2009 9:20 pm Missy87, We own a P class site due to fill. There is between 100-600mm across the site and we require an M class slab with 42 piers. With cut and fill this came in at about $16K. I was interested to learn about why this had come about. I downloaded and read through the applicable australian standard this is all based on, in particular how fill effects a blocks rating (AS 2870-1996). Ill include some interesting extracts which I have summarised: The basic classification of a site is as follows: A - Most sand and rock sites with little or no ground movement from moisture changes S - Slightly reactive clay sites with slight ground movement (0 - 20mm) M - Moderate reactive clay or silt sites with moderate ground movement from moisture changes (20-40mm) H - Highly reactive clay sites, high ground movement (40-70mm) E - Extremely reactice sites P – (cl 2.4.4) – Basically the soil cannot support the house, or, the site is subject to landslip, errosion, or, the site contains uncontrolled fill or controlled clay fill as stipulated in clause 2.4.6 (which is below) or the site is subject to moisture changes due to extreme site conditions significantly more severe than the reasonable site conditions. The soil test conducted determines the effect of moisture change among other things and determines the rating and depth of fill. Sites with fill are given other considerations: (Definition of controlled fill, Material that has been placed and compacted in layers by compaction equipment within defined moisture range to a defined density requirement in accordance with another AS) It appears this has happened on your block? Cl 2.4.1 (Summarised) Filled sites shall be classified as Class P except where the conditions of cl 2.4.6(c) and 6.4.2 allow another classification Cl 2.4.6 - Effect of fill on classification a) controlled fill i)Shallow fill: The classification of a site with controlled fill upto 0.8m deep for sand and 0.4m deep for material other than sand shall be the same as the natural site, prior to filling ii) Deep Fill: The classification of a site with controlled fill of material other than sand and deeper than 0.4m shall be P. Lots of other information about sand fillling b)un-controlled fill i) Shallow Fill: The classification of a site with uncontrolled fill upto 0.8m deep for sand and 0.4m deep for material other than sand shall be class P, unless all footings are founded on natural soil ii) Deep fill: The classification of a site with uncontrolled fill deeper than 0.8m for sand and 0.4m for material other than sand shall be Class P c)Reclassification of filled sites: A site filled with controlled fill and classified as Class P can be given an alternative site classification if assessed in accordance with the following engineering principles (which I wont write but include an assessment of movement, underlying soil conditions and the cracked zone) From what you have described it appears that the sites are being reclassified, even though there is deep fill on the blocks in accordance with c) above. I can only assume this is based upon science as well as the opinion of the engineers involved.. Also, be careful about comparing your soil report / foundation design from your neighbours as there can be large variations between adjacent blocks. From our experience, our site was classed as P due to the uncontrolled fill however we are able to get away with an M class slab due to the surface movement of the block being within the “M Class” classification. However, due to the fill, the screw piles are required. Hope you have got something out of all this…. Re: Fill In Lot - Should we be stressed? 9Jun 09, 2009 2:47 pm Sierra, Thanks a million for your time and effort in replying in such great detail. We still have this lot on hold pending the draft contract I want to look over prior to giving them a small deposit. It is quite stressful now, reading through that it is evident how reclassification may occur, and provided they place "controlled" fill as per the AS, we would have thought that screw piles were not necessary as it was controlled?? Have any other people here been required to have screw piles on controlled fill? abbstar11 - was your block in controlled fill over the whole block and where abouts was this? Once again thanks Siera for posting the extracts from AS2870 Re: Fill In Lot - Should we be stressed? 10Jun 16, 2009 9:07 am Hi Missy87, I am afraid we are in a similar position to you but have actually purchased the land already :/ Our small block is part of a redevelopment site which had a large chuck (but not all) of our block excavated and recompacted to a depth of up to 9m (yes nine). We now have the certificate of controlled fill from the developers which shows all the controlled fill and compactions done in up to 16 layers. The report says site should be classified as P and screw piles required to 9m. According to our builder, his engineer has estimated the 20 rear block 9m ones are $2000 and the 20 front ones are $800. It is only a tiny 225m2 block :/ Reading this thread has given me some hope regarding re-classification, need to speak further with builder. Regarding your land Missy87, can you get hold of the compaction certificate from land agent? That will at least confirm the controlled fill and compaction. Siera, many thanks for posting that info, interesting reading. 2 4343 yeah i couldnt picture it issue either, but i could clearly picture what they were doing wrong haha 2 5289 If you're in a flood zone, not only are you dealing with the importation of fill and laying it down in 150 lifts to achieve compaction, you're going to have to consider… 4 5528 |