Browse Forums General Discussion 1 Oct 04, 2006 12:07 am Hi everyone love this forum, I was wondering if someone would be able to give us some advise, We are about to sign a building contract and our site costs have come in at $30,000 a BIT more than we thought we thought around $10,000 max. We have to have a H slab cost $5,000 and the other big part of the cost is $17,000 for [b]Screw Piles [/b]about 45 of them does anyone have any Idea about these costs we are building in South East Victoria. I would really appreciate if anyone could advise us. All very Sad
Thank you in advance Di[b][/b] Re: H Slab - Screw Piles 2Oct 04, 2006 10:58 am If anyone is like me and wondering about what screw piles are, try:
http://www.instant.com.au/ http://www.infolink.com.au/articles/73/0C005B73.aspx http://www.piling.com.au/ 3timesbuilda Re: H Slab - Screw Piles 4Oct 05, 2006 9:41 am It may be a P class site & the engineer is looking for extra strength with increased mesh size & closer beam spacing. Hard to know without the full details.
I can't advise you as to how reasonable the cost is. The screw piles as with other similar systems such as Stratumpile are driven down until the required bearing pressure is achieved - this may be at 2 meters down or 4 meters or whatever so the cost will vary not only on the size of the home, the construction type and the number of piles required but also on the depth required to go to. 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: H Slab - Screw Piles 5Oct 05, 2006 12:32 pm Di :lol: Hi everyone love this forum, I was wondering if someone would be able to give us some advise, We are about to sign a building contract and our site costs have come in at $30,000 a BIT more than we thought we thought around $10,000 max. We have to have a H slab cost $5,000 and the other big part of the cost is $17,000 for Screw Piles about 45 of them does anyone have any Idea about these costs we are building in South East Victoria. I would really appreciate if anyone could advise us. All very Sad Thank you in advance Di Di, have they actually done the piling yet? It's simply not possible to quote a price on screw piles, as no one knows how deep they have to go; even with a geotech report you can only estimate. Re: H Slab - Screw Piles 6Oct 05, 2006 5:12 pm There have been considerable problems with residential slabs designed on screw piles on H class sites in Queensland. basically the design does not cope with swelling / heave. Sites have been "ripped" prior to installation of the screw piers/piles, in an attempt to allow some swell, but it has proved ineffective. I would like to hear if this issue has been addressed and what is the proposed solution. Screw piles 7Oct 05, 2006 8:26 pm Thank you everyone for your replies, we are building with Porter Davis and the soil test they had done came back from the engineer with this H slab with screw piles, and it was such a shock the price $30,000 all up for site cost. The land as I said is P and has fill on it and needs a cut and level of 700mm plus the deepth of the fill is from 2 to 3 metres. They said active soil, we have a compaction report but it does not show supervised fill, our neibours had there soil test done by the people that compacted the area so I have now had one done by them as well, it just came back and is a lot different to the first soil test even though it was done in the same area, they recomend a M moderfied slab and no screw piles, and a depth of 1.800 I sent this off to Porter Davis (who have been very good about all this) and they said because there was such a difference in the soil test they have ordered another one at there cost by the other company they use. They could not understand about the first soil test because the house across from us was also buildt by them and they had come in at M moderfied slab with $6,000 cost.
I thank you also for your information Chester, I had not heard about this problem with swelling, another builder I spoke to said he would put concrete piles in but I thought they were not as good, also the reason I thought they were using a H waffle slab was because it ajusts more to movment. I never thought I would learn so much about slabs I was really more interested in the bench tops and the colour of the walls until the $30,000 apeared in our costs. Thank you again everyone Di Re: H Slab - Screw Piles 8Oct 06, 2006 10:19 am Just to share my experience re site costs. I had my first soil test done by Hometec and it was classified as M slab. However, we also asked Clarendon Homes to proceed with the soil test. It came back with:
* Soils on this site are classified "M" in accrodance with AS2870-1996 * The footing system shall be designed by a qualified engineer due to the site being classified "P"! * The site costs are: $31K plus provisional allowance for screw piles $37K so total $68K! Even the sales consultant was confused and offered to follow up. Also showed them the Hometec report. Still haven't received any results from them despite the numerous calls. See my other thread on Clarendon Homes. What a waste of time. It looks like there is no consistent approach in soil test even with all the technology we have today. Re: H Slab - Screw Piles 9Oct 06, 2006 4:05 pm Hi all,
We are building with Porter Davis and in South Eastern Sub. We also had been hit with 30K site costs because soil test came to P site due to bad compaction of fill. We too are still very sad about the high site costs. Anyway we signed the contract and ready to start building. How do they detemine the depth of those screwpiles ? I guess its the depth that determine the site costs. Is there any way to check it has been done properly ? kwhy Re: H Slab - Screw Piles 10Oct 06, 2006 4:22 pm I feel for you all & I'm not sure how to put this without sounding insensitive so I'll just say it & cop the flack.
One of the golden rules of land purchase is to buy subject to a satisfactory soil test (geotechnical report) . . . . now i'll duck for cover. 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: H Slab - Screw Piles 12Oct 06, 2006 7:02 pm Some builders are pleased if the soil test result is "P". It creates a variancy clause which they can exploit. Ask for a breakdown of costs of the footing snd slab design. Also why the preference for screw piers? in shallow fill bored piers are way cheaper. Also installation depth should be through fill and into natural ground to achieve torque equivallent to 5 - 10 tonnes capacity. They also are designed only for compression (in the residential slab) so reactive soiol movements require additional slab design considerations. Re: H Slab - Screw Piles 13Oct 07, 2006 10:13 am Pardon my lack of knowledge here, but wouldnt it be cheaper to use stumps or sub floor rather than all these expensive fills, compaction and screw piles? I realise that this has other implications such as energy rating and height of the building etc. However, many builders do not even want to consider building with stumps or sub floor. Why? I did ask them but the answer is always: Oh! but we don't do that. Re: H Slab - Screw Piles 14Oct 13, 2006 5:42 pm Timber floor construction has become more expensive than a concrete slab on the ground, or at least that is what most project builders will tell you. Most building companies are simply not geared up for it. So they don't offer it as an option. Yet timber floor tiles over a concrete floor is becoming very popular. The public wants what the public gets? I thought the public gets what the public wants. Re: H Slab - Screw Piles 15Jan 20, 2011 11:56 pm get afew opinions is my advise....we got told the same thing and would have been up for 20 grand on top of slab costs....we got afew more people out and both said we didnt need the screw piles...through my investigations....screw piles are needed on very sloppy blocks with alot of moisture and they will give more stability in the soil...so if your block isnt like this then do some research or get another opinion...its alot of money!!!!! Re: H Slab - Screw Piles 17Feb 06, 2019 11:02 am Sort off stumbled across this forum so will attempt to assist. The depth of pile should be according to AS2870 table 2.5. This table relates suction change (Hs) with climatic zone. In Mel the climatic zone is either 2 or 3 with screw pile depth min 2.3m or 2.9m. The requirement for screw piles is to go 1.25Hs As2870 G6.3) to get below the zone where movement can occur, however this requirement does not exist for concrete bored piers - something I hope will be consistent in the future. A good screw piling company will comply with the code. Screw pile price has come down quite a bit in the past few years and when you consider the uncertainty of final cost of concrete piers and potential weather delays. From my understanding, the industry was rattled a few years ago with waffle slabs and homes cracking - this may be a reason for a more conservative approach to classifying sites. There are good options for reactive sites, one of which is a suspended ground floor slab www.polyvoid.com.au which has a track record of minimal cracking from reactive soils and compares very well cost wise. I must declare that I work for www.katanafoundations.com.au and www.polyvoid.com.au - however I am a Professional Engineer so my first obligation is to the broader community to assist where I can. Mark Armstrong BSc (Eng) MIEAust CPEng Development Manager http://www.katanafoundations.com.au http://www.polyvoid.com.au http://www.biax.com.au Re: H Slab - Screw Piles 18Feb 06, 2019 3:20 pm Welcome to the forum Mark and it is proper that you have upfront declared interest in the companies where you work. That is a decent approach and I for one would have confidence in listening to what you have to say. 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: H Slab - Screw Piles 19Feb 06, 2019 3:38 pm building-expert Welcome to the forum Mark and it is proper that you have upfront declared interest in the companies where you work. That is a decent approach and I for one would have confidence in listening to what you have to say. Thanks - day one and I got a call and assisted where I could. My interest is really in assisting folk with getting the foundations right. Everyone spends lots of time looking at taps and tiles only to live in a home with cracks in it - that's not right. If it is a while after the build - like a wet spell after many dry years - it goes to the insurer and we never get to hear about it. That means little feedback to the code committees like AS2870. Look forward to productive discussions. Mark Armstrong BSc (Eng) MIEAust CPEng Development Manager http://www.katanafoundations.com.au http://www.polyvoid.com.au http://www.biax.com.au Re: H Slab - Screw Piles 20Feb 08, 2019 3:27 pm Engineer building-expert Welcome to the forum Mark and it is proper that you have upfront declared interest in the companies where you work. That is a decent approach and I for one would have confidence in listening to what you have to say. Thanks - day one and I got a call and assisted where I could. My interest is really in assisting folk with getting the foundations right. Everyone spends lots of time looking at taps and tiles only to live in a home with cracks in it - that's not right. If it is a while after the build - like a wet spell after many dry years - it goes to the insurer and we never get to hear about it. That means little feedback to the code committees like AS2870. Look forward to productive discussions. brilliant and simple concept,start looking at what is between and under your walls and structures,this is what is to me the MOST IMPORTANT PART OF NEW BUILDS,stone etc is a luxury that you put in well after structure, trouble is emotion of what people see rules their heart,but poor structure can ruin lives,well said Mark. 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