Equilibrium Moisture Content

Equilibrium Moisture Content (EMC)

EMC, also known as “Equilibrium Moisture Content”, plays a major part in producing a successful timber floor however, it is not commonly understood how the EMC applies to timber floors and why would it make them perform differently in specific environments?

For the best way of explaining this you need to take into consideration 3 factors for your floors:

  1. Each product range has a different moisture content – you need to know this.
  2. Evaluate the job site – are you on a hill or bottom of a water way?
  3. Choosing the right time to install, as well as installation and finishing method.

The simplest way of putting this is that if you are on top of a hill with high winds, then your moisture content will be very different to your neighbours at the bottom of the hill. Likewise, if you’re on acreage or in the city, this impacts which products and install methods should be used. So this is where the math comes in:

It is important to have an understanding of the relationship between timber, humidity in the surrounding air and the dimensional changes that occur as a result of changes in humidity. During weather conditions of consistently high humidity, timber will absorb moisture from the surrounding air causing it to swell or increase in size. 

Conversely, during drier times when humidity is low, timber will shrink, reducing in size. Timber flooring, if not placed in a permanently controlled environment, will always move in response to hanging environmental conditions. In areas of high humidity such as the  tropics, or close to bodies of water, the atmospheric humidity in the air causes the floor to take up additional moisture. As such, care is needed to install timber flooring. 

This may necessitate acclimatisation depending on the product and additional expansion allowance may be needed. 

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RH = Relative Humidity MC = Moisture Content Cover width variation with changing relative humidity
Case Study

Location: Cleveland, QLD

Brisbane’s EMC average is normally 10.5% and stays pretty stable around that figure, but due to where Cleveland is located, close to the water, you need to add approximately 1.5% which makes a total of 12%.

In this case installation was needed mid-winter in August – the core issue here is that the EMC is now 9.0%, 3% below the calculated 12% Now 3% does not seem like a big deal however, just imagine for a moment standing on your floor and you have had up to 12mm movement per linear meter of flooring installed! Not going to look too pretty is it?

Now this is a subject that is consistently under large debate by different opinions in the industry: Do we acclimatise? What expansion is required? It can be frustrating to find factual information, however we pride ourselves on using our experience along with factual data to help you choose the best product that will perform for years to come.

When it comes to adding beauty and value to your home, one of the best possible ways is with solid timber flooring that will last a lifetime. By taking into account these different factors when looking at different timber based products you will always make the right decision.

Avoid the mine field of product selection and quality uncertainties, and contact our expert team today for further information on which products would be suitable for your location, so you can make the perfect product choice.


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