Browse Forums Building A New House 1 Jan 29, 2012 3:41 pm Hello, I'm new to the forum, I bought a land+house package in Point Cook and in the home contract from my builder it states H-Class Waffle Pod Slab(determined by engineer), and they have some promotions one is "upgrade to M-Class slab if required", last week the Client Liason Executive told me the building has been commenced and the slab is poured, then he sent me a "stamped plan" document which says the soil test is classification "P". I looked it up on internet and found that "P" class soil means there is some filling material and is the worst class for building houses, deep, strong and stable slab is needed; Then I found that H-Class Waffle Pod Slab is inferior than M-Class(not to mention I am not confident with waffle pod slab in general), I wrote to him asking the details of the slab but still waiting for his reply. At the meantime, what can I do? Maybe there is nothing I can do as the slab is poured, but I just want to know if the H-Class Waffle Pod suitable for Soil Test Class "P"? The result was issued after the contract so I hope they might alter the class of slab(but it is still waffle pod). I am worried if the slab need to be M-Class but they just stick to H-Class because M-Class upgrade is in promotion so they have to pay for it, can this happen? Thanks! Re: Soil Test Class "P" with H-Class Waffle Pod Slab? 2Jan 29, 2012 8:28 pm Welcome to H1,
For starters, read this link about soil types. What you will find is that H sites are more reactive than M and therefore an H slab will be superior. Interesting re: M slab upgrade? People classed as H in my area were being charged thousands more from the standard M class slab. Also P sites aren't necessarily the worst, you just need to find out what caused the P rating (this information will be in the soil survey done on the block which you should be able to get a copy of if you ask your liaison). http://www.soiltech.com.au/site_investigation.htm My experience from building with a volume builder is that an engineer will design the footings and the builder will build to what has been designed. There will need to be a footing design plan somewhere, perhaps ask your liaison for a copy so you can confirm what was designed has gone into the ground. We have a P class site due to fill and a standard M class slab with (alot) of concrete piers. Each footing design will be different so its impossible to say categorically that a H class slab is ok/not ok for a P class site cause they are all different. Good luck with it and I hope you get the info your looking for from the builder! Re: Soil Test Class "P" with H-Class Waffle Pod Slab? 3Jan 29, 2012 8:30 pm You have it the wrong way around, M is a lower class slab than an H class slab. If they have put down an H class slab but you have an engineers report saying it should be a P, i would get it checked ASAP Here is a listing of classes Class and Foundation (ground type) A - Mostly made up of sand and rock and has very little change when wet. S - Slightly reactive clay in the soil with only slight movement due to moisture. M - Moderately reactive clay with moderate movement due to moisture. H - Highly reactive clay site with High ground movement. E - Extremely reactive site with extreme movement due to moisture. P - Soft soils, land slip, mine subsidence, etc. Collapsing soils due to moisture and soil structure changes. Re: Soil Test Class "P" with H-Class Waffle Pod Slab? 4Jan 29, 2012 8:51 pm Thanks for all your replies! I am a bit unsure about soil class and slab class, are they the same thing? My contract says "H-Class Waffle Pod concrete slab(engineer determined)" and the promotion list says "upgrade to M-Class slab if required", this makes me think M class slab is superior than H class, but looking at the soil class A,S,M,H,E,P, H should be more reactive than M, but does this corresponds to slab class? Thanks again for your great help! edit: another document says the soil test result is "Classification P", if slab-class and soil-class are the same thing, then I would be more worried as they use H-class slab for P-class soil. edit: Sorry I was wrong, the contract says M-Class Waffle Pod Slab and the promotion list says Upgrade to H-Class Slab if Required, sorry for the mistake. Re: Soil Test Class "P" with H-Class Waffle Pod Slab? 5Jan 29, 2012 9:11 pm I think the important link is that A-E indicates how reactive the soil on the block is. As far as soil type goes, E is the most reactive (greater than 75mm). There is no "P" class soil. P class relates to the site as a whole. It says that there are certain features on the block (list in that link) which means that the site cannot be simply classed as A-E. I wont comment on your block, but will use mine as an example. The expected surface movement stated in our soil report was between 20-40mm (so should have been an M class site). However, cause areas of our block have about 350-600mm of fill, our site didnt fit as a "normal site" so was classed as P. Try to get your soil report and slab design and it will tell the full story. Re: Soil Test Class "P" with H-Class Waffle Pod Slab? 6Jan 30, 2012 5:59 pm Hi, today I got reply from them which clarified my doubts: the site has been classified as "P" as they found fillings but later they got Controlled Fill Certificate then re-classed as "H". Thanks a lot for your helps! Re: Soil Test Class "P" with H-Class Waffle Pod Slab? 7Jan 29, 2014 7:22 pm Just bumping this thread, because it has some excellent information in it. I just got my soil report, from StructuralWorks in Balwyn, Victoria ($400+GST) - pretty good service mind you. Will be getting the Engineering done here too, so that there are no questions/problems with communication between the soil testers and the engineers. I was quite perturbed when I saw a rating of "P" for my site. But, as stated on this thread, P is not necessarily "Poor", it depends on what has caused it to fall out of the normal categorisation of A, S, M, H, E. I then looked at the Characteristic Surface Movement (ys) - this was 20-40mm, and this corresponds to a Site Classification of M. The reason the site was classified as P is "to account for abnormal moisture conditions caused by trees on this and adjacent sites, as per AS 2870-2011." I guess lots of sites in established areas have trees! So, not the end of the world having a class P site. If you want to do extra reading on slab design, here are some links: CSIRO: Foundation Maintenance and Footing Performance http://www.bostongrp.com.au/documents/e ... 0Perfo.pdf CCAA: Guide to Residential Floors http://www.concrete.net.au/publications ... %20Web.pdf AS2870 http://www.ab.deakin.edu.au/online/vgal ... F/2870.pdf PS - I get a little worried when I read of people getting different soil tests, to try to change the category of the site, so that the slab is cheaper to lay. The slab is the most important part of the build, so, there's no way I'll be cutting corners on this. Perhaps seeking alternative slab designs for a particular soil class might be ok... 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 9854 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 13098 We were lucky in that our old house was so small (86 square metres) compared to the new house, they were able to take enough readings around the old backyard house before… 8 37142 |