Being Cognizant of Reactive Soil Sites (Part II)

Being Cognizant of Reactive Soil Sites (Part II)In our last post, we dove into the crazy world of reactive soil sites. Missed it? Here’s a brief recap of the fun facts that we covered:

  • Reactive does not refer to contamination in any way. It refers to the way that the soil will react when it comes into contact with different levels of moisture.
  • If the soil is clay based, it will have some degree of reactivity. The more that your soil will shift or move based on levels of moisture, levels just how reactive it is.
  • There is a governing body, or rating that measures reactive levels. It’s called the Australian Standard AS 2870/2011.

Today we talk more comprehensively about the different levels of reactivity and how to handle them. Here’s a handy list of the different ratings that the Australian Standard AS 2870/2011 encompasses:

Site classifications and movement based on soil reactivity

Class A (0-10mm)Stable, non-reactive. Most sand and rock sites. Little or no ground movement likely as a result of moisture changes.
Class S (10-20mm)Slightly reactive clay sites. May experience slight ground movement as a result of moisture changes.
Class M / M-D
Moderately reactive clay or silt sites. May experience moderate ground movement as a result of soil conditions and moisture changes.
Class H1 / H1-D (40-60mm)Highly reactive clay sites. May experience a high amount of ground movement as a result of soil conditions and moisture changes.
Class H2 / H2-D (60-75mm)Highly reactive clay sites. May experience very high ground movement as a result of soil conditions and moisture changes.
Class E / E-D (75mm+)Extremely reactive sites. May experience extreme amounts of ground movement as a result of soil conditions and moisture changes.
Class P (this is approximately 70% of building sites in Australia)Problem sites. The ability of the soil to evenly bear a load is very poor. Sites may be classified as 'Class P' as a result of mine subsidence, landslip, collapse activity or coastal erosion (e.g. dunes), soft soils with a lack of suitable bearing, cut and/or filled sites, or creep areas.
Ground movement as a result of moisture changes may be very severe, and these sites are typically subject to abnormal moisture conditions resulting from things like trees, dams and poor site drainage. If you are building on a Class P site you will need to consult a structural engineer.
The 'D' inclusion (i.e M-D, H1-D, H2-D or E-D)The 'D' in these classifications refers to 'deep' movements in soil due to deep variances in moisture. These classifications are mostly found in dry areas (e.g. north of the Great Dividing range, in places like Stawell, Horsham, Mildura, Bendigo, Shepparton and Wangaratta).

As mentioned in our last post, there’s never any reason to fear. Restumping Melbourne has dealt with every subfloor and soil issue under the sun, our team is equipped with the know-how on how to help.

Let’s talk first about the Class A and Class S sites. You’ll note that they range from 0-20mm of movement, pretty stable as far as the chart goes. For these situations, the Restumping Melbourne team leverages reinforced slabs with concrete beam footings. No additional work or maintenance is needed here, especially since you can always depend on the highest grade materials from our team.

On the other end of the spectrum we have sites with much more reactive soil. This includes Class H1, Class H2, Class E and Class P. It’s very important here to make sure you have a geotechnical engineer oversee a soil sampling test. The foundation of your home is extremely important and should be treated as such. With more reactive sites, our team will recommend concrete piers or screw piers beneath the footing beams on the slab. This provides maximum support and stability. This also digs much deeper into the soil where the moisture is more minimal and not nearly as much of a catalyst for issues.

Regardless of whether your soil measures in the Class A region or the D inclusion region, the Restumping Melbourne team will be on hand to make sure that reinforcing the foundation of your home or business goes as smoothly as possible.

Questions? Give us a shout. We’d love to help.

Being Cognizant of Reactive Soil Sites (Part I)

You’ve probably been told that it’s what’s on the inside that counts. Whether you’re receiving a scolding about superficiality, or a reminder to not judge a book by its cover, it is sage advice.

It has special meaning when you’re referring to the build of your dream home or business. After all, we’re talking about physical structures now. You can only guess what will happen if a home isn’t built on a foundation that’s firm and strong. It could slide down a hill at the first sign of a storm, or topple over in the middle of the night after being pushed by a puff of wind. While these aren’t the norm, they are possible. And that’s why we put such a heavy focus on the strength of the foundation of your dream home or business. It’s why we got into the business that we did. Because when the foundation is strong, everything built upon that can grow and prosper, including lifelong memories.

Being Cognizant of Reactive Soil Sites (Part I)You’re probably wondering what makes the soil underneath your foundation less or more safe. If you’re dealing with reactive soils, which we are in this post, then they’re less safe. Let’s dig into what reactive soils are:

The reaction that the term refers to, doesn’t have to do with contamination. The reaction refers to how the soil deals with different levels of moisture. Any soil in the clay family has some potential to change or shift shape. Those that have extra high potential to change or shift shape are referred to as reactive. The more they move, they more reactive they are.

Don’t go getting too worried about the current state of your home. It’s most likely that you received a soil test when your home was initially built. This test is administered by geotechnical engineers. Results are classified based on Australian Standard AS 2087/2011- Residential slabs and footings.  It’s the results of this test that help contractors and restumping teams like ours, determine the best way to fortify the foundation. One important item of note is that there are a couple of different moisture levels within the terrain, that a foundation needs to be prepared for. The geotechnical engineers refer to these as “normal wet” conditions and “normal dry” conditions.

No matter what soil classification you receive, Restumping Melbourne is prepared. All that is now required is choosing a subfloor which is both suitable for “normal wet” and “normal dry” conditions, but also for the style, size and shape of the structure which you’d like to build. You ask, and you shall receive. We’ve seen every which type of property and our decades of experience mean that we’re readily equipped to bring your vision to life.

We believe it’s important to educate our consumers about not only our services, but why they’re necessary. Stay tuned for our next post, when we’ll dive even further into the world of reactive soil sites and choosing a subfloor that makes the most sense for you.