When to & When NOT to Acclimatise Timber Flooring

Acclimatisation of Timber Flooring

If I was to write my definition of achieving a long-term stable floor: “For timber flooring, during its service life, to remain relatively stable, it should experience an inside house microclimate (EMC) similar to when it was originally laid.”

Factors to Consider

Keeping in mind wood is hygroscopic, that is a natural movement of expansion and contraction in relation to the timber’s exposure to humidity. There are many environmental changes in a home that will affect timber flooring. These include Heating, UV light from large glass windows and doors, as well as cooling.

Air conditioning is a factor that must be considered in today’s world. Overuse can have a negative effect on timber flooring boards. Split systems, based on a refrigerated system takes humidity from the microclimate where the floor is situated, causing unwanted board shrinkage. Conversely overuse of an evaporative system can have the opposite effect, causing unwanted board expansion.

When NOT to Acclimatise

To my mind, acclimatisation is a hangover from the past. And the reason I say that is because flooring producers in past eras had drying techniques that were not that good. Some may even have Air Dried their products. Consequently, timber flooring could arrive on site with moisture contents that were not consistent, and the process of acclimatisation was there to bring the moisture content close to the climate of the building to be floored.

In addition, the flooring was probably sourced initially from old growth, very mature logs, resulting in timber that was very forgiving. This cannot be said of much of today’s timber flooring, which likely is sourced from re-growth smaller trees resulting in more immature re-growth logs that are not as forgiving and can react to marked climate changes.

Today, all major flooring producers have very sophisticated drying techniques and can be relied on to deliver their flooring products at the average equilibrium moisture content (EMC) of their two major markets, Melbourne and Sydney, which is about 10% – 11%.

Recently I visited a house where the client had acclimatised the timber flooring for 2 weeks. Our records showed, in that time the flooring probably increased by about 1% moisture content and grew up to about 5 millimetre’s over a 10 board measurement since installation. Accordingly, I concluded, the acclimatisation process, at this time of year (winter) to be counterproductive. This is because the flooring absorbed moisture from the atmosphere causing the flooring to grow, not only in width, but also within the tongue and groove, which made it difficult to have an easy match between boards.

By acclimatising at this cooler time of year the boards duly picked up moisture from the high humidity and accordingly, the acclimatising became counterproductive with the high possibility of shrinkage in the following warmer times ahead.

Similarly, if the acclimatising was in the summer months the boards may lose moisture and contract in size only to later to pick up moisture and expand in the cooler times which could result in unwelcome board movement.

Situations When Acclimatisation is Recommended

If the project is a replacement or a room to be floored and the air conditioning is in place, acclimatising certainly can be achieved. That said, the timber flooring boards should experience conditions typical to ongoing normal living conditions.

The key to the timber movement is the local climate during the floorings service life. So, if the building to be floored is geographically located in a high humidity area possibly like Falls Creek, acclimatisation is advisable.

How to Acclimatise Timber Flooring

Some mistakenly believe leaving the timber flooring in a block stack for a period of time will acclimatise each board. It certainly will not.

The exercise is to have each board experience the microclimate the flooring boards will experience, including the normal use of the air conditioning.

Accordingly, each board should be placed with a gap in rows in the flooring area, then spacers are placed on top of boards and the next row is replicated. This allows air to circulate around each board.

Normal time allowed could be about 3 weeks for 19-millimetre boards and about 2 weeks for thinner overlay boards.

My final comment is a word of caution:

The above comments are based on my experiences of dealing with timber flooring problems over many years, so they must be taken as a suggested course of action.

Accordingly, it may be prudent for flooring installers to seek advice for all different situations.

Explanatory Notes

Hygroscopic: Wood is a natural substance and can pick up or lose moisture content under varying conditions, that may result in board movement.

Ultraviolet Sunlight (UV): Can cause unwanted shrinkage (through windows) or flooring boards to fade in colour.

Heating: Particularly in front of a heating appliance can cause unwanted shrinkage.

Equilibrium Moisture Content (EMC): Timber flooring will adjust to the climatic conditions it is exposed to. If left externally, the moisture content will be different in winter to summer months.

Internally, it is important to maintain an even internal microclimate from season to season.

For information on flooring, explore our timber flooring range online or visit our Circa showroom in Port Melbourne, so you can see and feel the timber flooring for yourself.