We have experienced unusually hot and dry weather over the past few weeks and it is not only our plants that are suffering.

Wooden log cabins are showing signs of shrinkage and open joints. Typically this shrinkage will be noticed at top of window height.

The reason is fairly logical when you understand that timber shrinks more across the grain than along the grain.

Therefore in a log cabin where you have deep windows with a vertical timber running the full height of the window, there is going to be little shrinkage, as the grain runs along the length of the timber. The width of the board will shrink, but being only a single board width, this will seldom be noticed.

However for the horizontal boards that make up the walls of the log cabin, the story is different. As the grain runs horizontally along the timber, the width of the board will shrink. Here we have a number of boards sitting on top of each other forming the wall from bottom of window to top of window – and each board will shrink in width, or as they are laying horizontally, their height.

Towards the bottom of the window the boards that make up the wall will keep together as gravity will let the boards above rest on the board below.

Generally there is an horizontal board running over the top of, and resting on the top of the window – this cannot be pulled down by gravity, due to the long grain of the window frame not contracting very much in it’s length. Therefore any shrinkage will be seem near the board resting on the top of the window.

Now an image taken a couple of months later and after a couple of cooler days. You can see the boards are now interlocking again. This image taken in the evening, hence the variance in colour from the initial image.

 

A log cabin is just one example of the effect of timber drying out. Yet there are many other similar instances of timber shrinkage caused by this prolonged warm dry spell.

Grange Fencing have recognised this problem and have prepared a pdf document describing some of the problems and ways to minimise the visal effects on your garden products.

Follow the link to the Grange Fencing document :-

Understanding Timber

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