Browse Forums Building A New House 1 Oct 11, 2007 12:04 pm Can anyone tell me why some builders use 'white foam' in their slabs and other builders don't??
Both houses on either side of us have double the thickness slab height than ours and also the 'white foam' was used in both of theirs. We are all building on landfill and requiring "P" class slab. Should I be concerned??? Re: White Foam in Slab 2Oct 11, 2007 12:07 pm AFAIK the foam (waffle pods) serves to save concrete while allowing for a significantly raised floor level. Re: White Foam in Slab 3Oct 11, 2007 4:29 pm I think structure wise you shouldn't, as long as there's some sort of engineering certified things on that. All the slabs stuffs are hidden underground and you won't be able to see it after house finished.
It's just different ways of doing things. Like the photos from "parker" blog shows their builder use concrete footings for all the walls surrounding the slabs, but our builder drilled 69 concrete pierings under the slab and there wasn't any concrete footings surround the slabs at all. But, assuming all the houses in your area are all in single storey or double ones, if both your neighbours' houses are taller/higher than yours than I would be a bit concern... Re: White Foam in Slab 4Oct 16, 2007 5:50 pm Jac08 Can anyone tell me why some builders use 'white foam' in their slabs and other builders don't?? Both houses on either side of us have double the thickness slab height than ours and also the 'white foam' was used in both of theirs. We are all building on landfill and requiring "P" class slab. Should I be concerned??? That means that your soil is reactive (because of a landfill) and the waffle pack supposed to prevent cracking. If you haven't live on reactive soil here are some examples: your door are suddenyl opening, or you cannot close them due to the movement of the soil after big rain. Should you be concern? I have built on class "P" soil which is assessed as HIGHLY REACTIVE and engineers designed a reinforced raft slab that costed us $23k. This is double story house. If you build one storey it probably is fine, but if you build double story ask the question. In any of this circumstances you need to remember to establish a good drainage system to keep the moisture away from the house. Also you need to keep trees with invasive roots away from the house. cheers kate Re: White Foam in Slab 5Oct 17, 2007 10:34 am Reactive soil has nothing to do with whether it is landfill or not.
Having reactive soil simply means that it - the soil - reacts to changes in the water content in the ground. That is, shrinking as their moisture content decreases and swelling as it increases. This can cause cracking in the foundations and walls if you built not knowing you had reactive soil. Reactive soils are typically clay soils. But not always, some of the black soil in SA and Western NSW is reactive as well. M" means moderately reactive soil - some expansion or contraction. "H" means highly reactive. I for instance am built on a clay soil classed as reactive M. And with the lack of rain we have experienced some minor cracking. From the standards for those who are interested ... CLASS 'A' - Little or no ground movement CLASS 'S' - Slightly reactive sites CLASS 'M' - Moderately reactive sites CLASS 'H' - Highly reactive sites CLASS 'E' - Extremely reactive sites CLASS 'P' - Problem site Hi everyone, first post. I'm a home builder doing most everything myself. Re: White Foam in Slab 6Oct 17, 2007 10:37 am louie M" means moderately reactive soil - some expansion or contraction. "H" means highly reactive. I for instance am built on a clay soil classed as reactive M. And with the lack of rain we have experienced some minor cracking. From the standards for those who are interested ... CLASS 'A' - Little or no ground movement CLASS 'S' - Slightly reactive sites CLASS 'M' - Moderately reactive sites CLASS 'H' - Highly reactive sites CLASS 'E' - Extremely reactive sites CLASS 'P' - Problem site Thanks louie for the information, we have been asking that question for ages and we now finally have an answer about what each class actually means! Will put that information on my blog if you don't mind. Re: White Foam in Slab 7Oct 17, 2007 10:40 am hey louie, can you please advise what an M-D class slab is then?
We had 2 soil tests on our block, by 2 different builders, the first one classed it as M-D and the second one as a H class slab? What is the difference between the two? Re: White Foam in Slab 9Oct 17, 2007 10:52 am **Phoenix** hey louie, can you please advise what an M-D class slab is then? We had 2 soil tests on our block, by 2 different builders, the first one classed it as M-D and the second one as a H class slab? What is the difference between the two? The "D" means that there is deep moisture changes greater than 3m and is a characteristic of dry climates. M-D represents a moderately reactive soil with deep moisture changes. H represents a highly reactive soil with shallow moisture changes. Hope that makes sense. From standards AS 2870 - "Residentail slabs and footings - Construction" You should find out why you got two different readings as well. Re: White Foam in Slab 10Oct 17, 2007 11:01 am What's better to have a M-D or a H class?
Our builder "H" quoted extra for the H slab as they only provide a M class as std? Which one would cost more in your opinion? The plans have been drawn and contract signed... Is it too late to query the difference in soil classes now? Re: White Foam in Slab 11Oct 17, 2007 11:07 am **Phoenix** What's better to have a M-D or a H class? Our builder "H" quoted extra for the H slab as they only provide a M class as std? Which one would cost more in your opinion? The plans have been drawn and contract signed... Is it too late to query the difference in soil classes now? I would prefer a M-D over H any day. M is moderate ground movement from moisture changes, H is high ground movement. Your builder is doing the right thing by building to a H standard. If he built to a M and your soil was really H then you could be in all sorts of trouble. Re: White Foam in Slab 12Oct 17, 2007 11:30 am Thanks Louie, appreciate your help...Feel a bit better now. Most of the estate has been classed as H or P anyway, so better safe that sorry. Re: White Foam in Slab 13Oct 18, 2007 6:00 pm Hello All,
I found sth quite interesting on the net: A SIMPLE ‘HOW TO’ GUIDE TO PREVENTING STRUCTURAL DAMAGE TO YOUR HOME. Plan your landscaping, lawns, gardens and foundation care to avoid ugly and costly problems. http://www.bsa.qld.gov.au/NR/rdonlyres/747691DD-2515-4756-8481-53B0391EACB0/0/SubsidenceHomeownerBookletcorrected240305.pdf It is on BSA website. thanks kate Oh no! I would use a can of expandable foam ( there are some that will take render) then cut it back and render over the top 1 4141 There is nothing in the various codes and standards that puts this requirement on the builder to do. I think that is what you are asking. Don't waste time trying to get… 5 2396 Looking for advice on whether this variation in tile colour is acceptable. The large tile on the left was used in my main bathroom renovation 1 year ago. My ensuite… 0 8488 |