Browse Forums Building A New House 1 Jul 01, 2010 10:39 am Site Start: 10th September, 2010 PCI : Friday 27th January, 2011. Handover: 3rd February, 2011 Build Thread: viewtopic.php?f=31&t=37677 Re: H Class Slab Costs - HELP PLEASE 3Jul 01, 2010 11:03 am Site Start: 10th September, 2010 PCI : Friday 27th January, 2011. Handover: 3rd February, 2011 Build Thread: viewtopic.php?f=31&t=37677 Re: P Class Slab Costs - HELP PLEASE 5Jul 01, 2010 11:38 am From a couple of geotech websites: Quote: The system of site classifications is mainly focused on clay sites that swell and shrink with changes in moisture content as these sites are known to have the most problems. Clay sites (reactive) are classified as S, M, H or E as follows: S Clays that have not given trouble in the past. M Moderately reactive clays that may cause minor damage to brick houses on old-style light strip footings. Moderately reactive clays are common in Victoria. H Highly reactive clays that often damage houses, paths and fences. E Extremely reactive clays that frequently damage houses even with strong footings. Generally rare in major cities except Adelaide. Other occurrences include outback NSW, Darling Downs, Geelong and Horsham. Proper maintenance of such clay sites requires that the moisture content of the founding clay for the footings are kept as consistent as possible. Despite proper design, construction and foundation maintenance, some minor cracking can be expected in most masonry walls on reactive clay sites. Cracks up to 3mm in width are considered minor and cracks up to 5mm in width are considered large but crack widths of 15mm to 25mm are not uncommon on reactive clay sites that are poorly maintained. I can vouch for this. We had a nice long 10-15mm crack in our brickwork at the old place. Not structural, since it was brick veneer, but not pretty. Mind you, I'm not sure how one is supposed to "maintain" a clay site. It's not like you can stand around watering it when it's dry and drying it out when it's wet. Quote: ...the Site Classification must consider many aspects of the site, not just the reactivity of the soil. P sites are those that include other factors that need to be brought to the attention of the owner, builder and footing designer. A “P” classification does not indicate a specific Ys value and is described as a “Problem” site. The reasons for a P classification include: • Growth &/or Removal of Trees will cause Abnormal moisture conditions in the subsurface soils; • Unusually high moisture conditions caused by water flow, ponds, dams etc; • Sites with Loose fill which can be either “controlled” or “uncontrolled”. The P Classification depends upon the depth and type of fill; • Sites with poor bearing capacity, soft soils, or soils which are prone to collapse; • Sites prone to mine subsidence, land slip, piping or coastal erosion; • Sites which for one reason or another cannot be classified as normal sites; One thing that might help if fill is an issue (and it sounds like it may be) is to see if there's a controlled fill certificate available for your block. The developer will be able to give you a copy if it exists. That cut a couple of thousand off our site costs. Re: P Class Slab Costs - HELP PLEASE 6Jul 01, 2010 3:10 pm thanks again, kek, gosh when you read P is for Problem is doesnt instill any confidence, spoke to the ppl who bought block next door and their slab is designed for H class, said they queried their site costs and ended up ringing developer to obtain a compaction report and showed this to their builder and had it classified as H - I know it's cheaper to go with H but I want to make sure our slab is still standing and not all cracked etc in 15 years or so, so I guess we will go with what our engineer has said what class it should be. Site Start: 10th September, 2010 PCI : Friday 27th January, 2011. Handover: 3rd February, 2011 Build Thread: viewtopic.php?f=31&t=37677 Re: P Class Slab Costs - HELP PLEASE 7Jul 01, 2010 3:21 pm ring09 thanks again, kek, gosh when you read P is for Problem is doesnt instill any confidence, spoke to the ppl who bought block next door and their slab is designed for H class, said they queried their site costs and ended up ringing developer to obtain a compaction report and showed this to their builder and had it classified as H - I know it's cheaper to go with H but I want to make sure our slab is still standing and not all cracked etc in 15 years or so, so I guess we will go with what our engineer has said what class it should be. Haha! Don't let the "problem" thing freak you out. We've lived in this area for 25 years and know all about the rotten black clay, and the fill that always gets dumped in new estates. We had craters open up in our back lawn every summer - you could lose a small dog in them. You can thank Mount Cooper (that hill in Bundoora with the water tower) for spewing out its volcanic contents about 6,000 years ago - that's where the lovely grey-black mud comes from. When we built the first time, the soil classification system was a bit different. Council had our block noted as "intermediate" and the house was built on 600mm stumps. A year later when we wanted to build a deck and pergola, they'd changed the classification to "unstable" and made us sink the stumps and posts a full metre. That deck and the carport we built never moved. Can't say the same for the house... With this place, we took the same view as you - we'd prefer to spend a bit more money and ensure our house has the minimum of movement, than to risk any structural damage. 18 months on, we have a few gaps between cornices/walls and skirtings/walls, but those are expected and nothing a tube of No More Gaps and some paint can't fix. Better to over-engineer the foundations than go the other way. Re: P Class Slab Costs - HELP PLEASE 8Jul 01, 2010 9:09 pm We were charged an extra $10000.00 for a P class site(fiil &reactive) and M class Modified Slab . No one incl the builder can say why that is . I then rang PROCON the guys who build and pour slabs for a living. He said thats about right ? What gets me is how come the builder charges an extra $10K for a Mclass modified slab when they include a M class Slab in the base price of the house.The house is 273sq mtrs So for a extra bit of reinforced( SL82 instead of SL72) mesh plus concrete and deeper edge beems ,10K give me a break. Its a rip off Re: P Class Slab Costs - HELP PLEASE 9Jul 03, 2010 10:41 pm We are building in Lalor, VIC and we paid $14K to upgrade our slap to P class. That's on top of the existing site cost. We weren't aware of this until we were given the contract. We are building with M3tr1c0n and asked them why the extra cost. They said that they have to build on a P slab because the soil report states high moisture soil (clay). We were puzzled at first but got over it and telling ourselves, "guess its better cause we paid more." Surprisingly, our neighbours are building on a H slab and they are directly beside and behind us. I'm confident their soil is the same as ours. Nevertheless, like we keep telling ourselves "guess its better cause we paid more." ---------------- upgraders Bel-Air 37 : Contemporary Fascade (Major Interior Makeover) <img border="0" src="http://tickers.TickerFactory.com/ezt/d/4;10738;127/st/20100317/e/Site+Start/dt/14/k/8a06/event.png"></a> Re: H Class Slab Costs - HELP PLEASE 10Jul 03, 2010 10:58 pm kek ... We only had 1-1.8m of fill and piering along the rear edge of our slab to protect the sewer we built so close to ... Hi Kek, so you only had piers at that edge/side of the slab, ie. the rest of the slab is sitting on waffles only? Like one string line of piers and then no piers in the rest of the slab? My signature is distracting people from my wise posts ... Re: P Class Slab Costs - HELP PLEASE 11Jul 04, 2010 10:16 am The northern suburbs is full of clay and rock......some areas are really bad fo rthe rock. Have a look arounf older type houses in lalor thomaston and epping....All the brick fences are stuffed because of the clay. Re: H Class Slab Costs - HELP PLEASE 12Jul 04, 2010 10:26 am Lex kek ... We only had 1-1.8m of fill and piering along the rear edge of our slab to protect the sewer we built so close to ... Hi Kek, so you only had piers at that edge/side of the slab, ie. the rest of the slab is sitting on waffles only? Like one string line of piers and then no piers in the rest of the slab? Yup, that's right. Only the rear edge of the slab is piered - I think there are about 10-12 of them from memory. The sewer easement is 2m wide and we built to within 100mm of it at one end, and about 300mm at the other (the block isn't square, so the rear fence runs at a slight angle). A lot of blocks near us have piering to the entire slab. LOTS of fill in this area. Ours is compacted, so the fill wasn't a big deal, but protecting the sewer was. Re: P Class Slab Costs - HELP PLEASE 13Jul 04, 2010 11:34 am Hmm ... so it's not uncommon - there was a thread with the same issue by andy a few months ago ... his slab wasn't piered at all - which makes me wonder why do they seem to make it oh so important here in their contracts ... My signature is distracting people from my wise posts ... I am not sure whether Perth has its own way of doing things in regards to this. Most of Perth has class A (sandy soil), except for some areas near rivers or hills. 2 13053 The Soil classification has little to do with piers. The purpose of the classing of the soil is to identify the clay content and the "average expected range of movement… 2 9841 I don’t think so as the floor area over 300 square meters then it is class 3…. 12 17925 |