Moisture Content in Timber Handrails and How to Prevent Your Handrail Joints Opening Up

One of the biggest frustrations on site (for all parties, especially here at Haldane UK) is if the handrail joints open after installation – which is why we try everything we can to prevent this from happening.

So why does movement in timber handrails happen?

9 times out of 10, movement in timber and the opening of handrails joints, is down to the moisture content in the timber and fluctuations in the on-site conditions.

Wood is hygroscopic (sorry for the technical term), which in layman’s terms means that it absorbs moisture from the air.

As humidity in the air increases, the moisture content in the timber increases and causes the timber to expand.  Likewise, as humidity decreases, the moisture content decreases and causes shrinkage in the timber.

So, for example, if the working area is exposed to the elements or there are wet trades, such as plastering or concrete works, being carried out in the area, the relative humidity is likely to increase, causing the timber handrail to expand.

Likewise, if the heating is turned up in the building the humidity decreases and the timber is likely to shrink and this is when the handrail joints can open up.

This is more likely to occur when sudden changes in the humidity is experience and the timber suffers what is referred to as shock weathering.

It is therefore important to ensure the timber is stored at a moisture content which reflects the intended environment.

As the average humidity in a UK home can vary from 40-60%, we have procedures and processes in place to keep our timber stocks in an environment which has 10-14% moisture content.

The moisture content is measured prior to machining and prior to despatch to ensure the minimum of movement on site.

What Can You Do On Site to Minimise The Risk of Timber Handrail Joints From Opening?

  1. Ensure handrails are stored safely in the environment being installed (not outside)
  2. Allow handrails to spaced with all surfaces exposed – do not pile them up
  3. Avoid sudden changes in temperature in the environment – do not turn up the heating to its highest level to dry out the paint or plasterboard
  4. Install handrails after all wet trades have finished
  5. If wet trades must be called back, ensure timber handrail is completely wrapped in vapour impermeable material (like plastic) with as few gaps as possible
  6. Measure moisture content prior to installation to ensure it is within the acceptable levels of the environment