Browse Forums General Discussion 1 Dec 12, 2010 12:44 pm Firstly thankyou to everybody who posts on this site, the advise and information everybody provides is invaluable! My parents had an independant soil test done on a block they planned to purchase, we are finding it hard to understand, the only thing we can gather is that it is bad. The report was 5 pages but i've tried to just include what i THINK?? is most important. The soil test stated: Class P site because of deep clay and currently saturated very soft (fluid) soil mainly due to recent heavy rain but possibly common. Natural clay moderately reactive. Medium slope, no trees. 2 bore holes - similar results for each. 0 - silt, grey, firm, moist 500 - light grey, saturated, very soft, fluid pouring below 1000 - light grey, firm, moist 1300 - clayey, tan & light grey, firm 1500 - clay, tan & light grey, stiff, moist 1600 - end STRIP/STUMP FOOTINGS - Footings should be founded at least 100mm in natural stiff clay. Minimum depths 500mm. PIERS - Found at least 200mm in natural stiff clay. Minimum founding depth 1800mm. PILES - Founded at least 1000mm into natural soil. Minimum founding depth is 2400mm. Design beams and & slabs as suspended. Pre boring may be required to reduce vibration damage to structures or for penetration. Someone from the company my parents plan to build with did a site inspection and said it was a good block, he thought approx 500mm fall. However after speaking with a neighbour from the area we have been told there may have previously been a dam on the block and their site costs were almost $50,000. Basically anyone have any idea how much site costs may be? Is this really bad? More trouble and money that it's worth? Also probably a stupid question but are the strip/stump footing, piers and piles all required or are they just different options? I have looked through the site costs thread but i couldn't seem to find a post that had similar requirements. Sorry if my post is too long! Any feedback would be greatly appreciated. Cheers Kat Re: Please help me understand soil test!! 2Dec 12, 2010 3:50 pm They will give you different engineering options for each of the different type of slab styles, so waffle / raft / strip footing / peirs. You just choose one. With fall, it all depends on the building envelope. They may say medium fall, but that might be 1 meter over 50 meters - which means a building envelope of 15 meters may not have much fall at all - also, don't forget the fall is calculated on both axis (so across and up/down). looks like the ground is quite soft though - hence the deep peiring. A builder will be able to give you an estimate before you hand over cash. Chances are though that you might find the slab / site cost more expensive. Well done on doing the soil test first - you're one up on most people! Amazing_Venice [size=50]Signed: 31/07/10 Colour Appointment: 08/09/10 Deposit Tender 20 / 09 / 2010 Final Contract Signed 18 / 11 / 2010 Slab laid 02 / 2 / 2011 Frame completed 25 / 02 / 2011 viewtopic.php?f=31&t=37417&p=553032&hilit=oxford#p553032 Re: Please help me understand soil test!! 3Dec 12, 2010 10:19 pm Thankyou for your reply and clearing up the slab styles for me, after days of reading this forum you would think I could work it out for myself! I will forward the soil tests to the builder tomorrow and hopefully they can give us a rough idea of site costs before the block gets bought by someone else. My parents have budgetted $$$ for extra site costs, but we were thinking $20,000 - $30,000 worst case scenario, now I am worried that they could get stung up to $75,000 like i have read about on other threads. Thanks again Re: Please help me understand soil test!! 4Dec 13, 2010 6:43 am Althought the deep slab/footings mean more concrete (thereforeore cost) big site costs (50k up) tend to be steep slopes that require huge amounts of excavation and cut/ fill. How bad is the fall? Good luck with the builder today!! Amazing_Venice [size=50]Signed: 31/07/10 Colour Appointment: 08/09/10 Deposit Tender 20 / 09 / 2010 Final Contract Signed 18 / 11 / 2010 Slab laid 02 / 2 / 2011 Frame completed 25 / 02 / 2011 viewtopic.php?f=31&t=37417&p=553032&hilit=oxford#p553032 Re: Please help me understand soil test!! 5Dec 13, 2010 7:05 am 0 - silt, grey, firm, moist 500 - light grey, saturated, very soft, fluid pouring below 1000 - light grey, firm, moist 1300 - clayey, tan & light grey, firm 1500 - clay, tan & light grey, stiff, moist 1600 - end STRIP/STUMP FOOTINGS - Footings should be founded at least 100mm in natural stiff clay. Minimum depths 500mm. PIERS - Found at least 200mm in natural stiff clay. Minimum founding depth 1800mm. PILES - Founded at least 1000mm into natural soil. Minimum founding depth is 2400mm. Design beams and & slabs as suspended. Pre boring may be required to reduce vibration damage to structures or for penetration. I'm not sure what to make out of this report - eg. it says that at 1.5 m deep, the soil is still moist (was it bucketing recently in the area?), and they marked the 1.6m test hole as "end". What does this mean? Can you call the company who did the test and ask for a detailed explanation? Does it mean that they didn't bother to (or couldn't) test deeper than 1.6m? They do mention min footing of 1.8 / 2.4 m (option 2 and 3) - so how can they be sure of the recommended footing depth when they didn't test any deeper than 1.6/1.5? (perhaps approximation based on experience?) I also don't understand their recommendations for footings - eg. "Found at least 200mm in natural stiff clay. Minimum founding depth 1800mm." - How can a pier be "founded" at least 20cm deep, but have "min. depth" of 1.8m? As far as I know, piers are fully in the ground, so there would only be one measurement (depth). Unless they meant that out of min. 1.8m, at least 20cm must be in "natural stiff clay". And then, if so, what is the natural stiff clay and at what depth did they find it? Their findings (holes) don't mention at which depth they found the natural stiff clay, but then they used it in recommendations . Maybe it's just the wording. My signature is distracting people from my wise posts ... Re: Please help me understand soil test!! 6Dec 14, 2010 11:25 pm Yeah we found it confusing too Lex, I was really careful to copy the wording exactly becaude I thought it was odd, thankyou for pointing out what you found difficult to understand, it made me feel better that I wasn't the only one who found it difficult to follow! We spoke with the soil tester and he couldn't say if the excess moisture was due to recent heavy rain or ??? the block was on an old dam site. The builder had a look over it and thought it was quite vague and not very thourough. Luckily the builders have been fantastic, they have offered to do a free soil test and new home order, then based on that they said they will provide a fixed price site cost, this is all before my parents have even bought the land, apparently there are currently no other interested parties in the land so there so is no major rush, I think my parents are very lucky!! They are prepared to pay extra site costs but at least this way they know exactly what they are up for without signing anything!! Thanks for your reply's guys, really appreciated!! : ) Re: Please help me understand soil test!! 7Dec 15, 2010 6:14 am You're welcome and good luck! Would be interesting to see what test results the builder gets to compare the two - maybe you could post some extract from it? Being an old dam site - maybe that's the answer for the moist soil? Maybe all the barriers haven't been removed, so water stays for longer ... Or, is this site at the bottom of the larger area (could explain the moisture) .... What is the surrounding terrain like? My signature is distracting people from my wise posts ... Re: Please help me understand soil test!! 8Dec 16, 2010 2:21 pm It is the first sentence which is important - It is a class P site. This is what the engineer will use to design the concrete footings and slab and specify structural components. Nathan Re: Please help me understand soil test!! 9Dec 20, 2010 7:36 pm Well after all that someone else bought the block before my parents builder had a chance to do the soil test!!! Never mind, just keep looking and try and act a bit quicker next time. 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