What’s a soil test? Why do you need one before renovating or building your new home? And what are the 3 mistakes I see homeowners make that can cause extra cost, time delays and loads of stress?
Watch this video to find out.
And here’s the transcript, if you prefer reading to watching …
What’s soil test?
A soil test is where a geotechnical engineer will come out to your site, and they will take samples of your site. Basically they’ll core down and they see what the soil is doing at different levels under your site. From that they’ll be able to see how “reactive” the soil is on your site.
The reactivity is how much it will expand, or move, and what type of structural foundation and support it will provide to whatever you’re putting on it. That information is really important then for the structural engineer to be able to design the structure for your house, the foundations, the footing, the slab design.
Once they get that information they then classify your soil. There’s different levels of classification. That is important information that the structural engineer needs to do their structural design.
There’s three mistakes that I see homeowners make when it comes to getting soil tests done for their site.
The first one is they only get one core done.
As I said, a geotechnical engineer comes out and they take this sample. What happens is that in one site, even in a suburban site of six hundred square meters, you can have very different types of soil conditions across that one site.
When you’re just getting one soil sample done then that will give one piece of information that then the whole structure is designed. You can see that you may then start excavation work and find that the soil is actually different in a different location and requires different things.
That could create some headaches on site. Definitely get at least two done, if possibly not more.
That leads on to my second mistake that I see homeowners make …
… and that’s that they don’t do any design work first. In terms of getting some design work done first, what that does is show exactly where you’re going to be building and then you can get soil tests done in those areas.
I have a recent example where a homeowner had got some soil tests done and then got their design work done.
What happened was that their site was at the bottom of an old valley that had been filled, and there was one edge of their site which was just slop and mud, and that was where footings were going.
But the soil test had been done elsewhere on the site and the structure design done for the soil in that area.
What happened was the builder started excavating and you couldn’t find anything decent to actually put the footings for the extension into, so they had to do screw piles.
That’s just unexpected information that hadn’t been budgeted for, and is being discovered on site, and just has to be dealt with on the fly. Which can cause a lot of stress and headaches, and of course extra costs.
Get some design work done first, and then you can give that to the geotechnical engineer, and say this is where we want soil tests done, this is where footings are going to be, and foundations are going to be, and we need information about.
The third mistake that I see homeowners make is that they don’t get professional support in actually commissioning the geotechnical engineer.
Professionals speak to professionals in the industry in different ways than you might be able to speak to them. And give them different information and different briefing about how to get the soil test done.
It’s really good to get professional support from you designer in terms of asking the geotechnical engineer the right questions and giving them the right briefing to make sure that they’re getting the best information for your site, and that they only need to come out once.
Those three mistakes again.
Only getting one soil sample done of the site.
Not doing any design work first, to give the geotechnical engineer information about where to do the soil samples.
Not getting any professional support in commissioning the geotechnical engineer.
Soil samples are really important, and you can imagine when the equipment comes in to do those cores, sometimes they can’t get access to exactly where you need those soil test done. Just take that into account, Really get some support and help in making that happen or you project.
You may find too that if you’re doing an renovation that involves demolishing some of your existing house in order to extent that you will have to get two soil tests done, one before the demolition and one after the demolition.
I hope you found that helpful. I’ll see you later.
Other blogs you may find useful …
Are you procrastinating about your renovation and new home, or planning? Here’s how to know.
Don’t want to compromise in your project? This may help you.
What adds value to your home for free? It’s maximising these assets.