The Case Against Pressure Treatment of Log Cabins
Many potential customers have pre conceived ideas that pressure treated wall logs for log cabins are essential for the longevity of the cabin.
We wish it was as simple as that as we have no problem in carrying out the pressure treatment process. However there are several advantages and disadvantages that need to be considered before making such a decision.
It is an expensive operation and this is reflected in the considerable extra cost you pay for the cabin.
It must be appreciated that if the wood stock is from a good source it will be a very dense tight grain. Unlike fence posts for example, which are very porous open grain timber and allow the pressure treatment to reach the central core of the component, with dense grain Northern Scandinavian Pine the treatment under similar pressures only reaches just below the surface, and this degree of penetration is available from some of the top aggressive weather protectors on the market at far less cost.
There will be a discolouration of the wood from light straw to dark green and this may vary from log to log depending on where in the pack the component was when it was subjected to the pressurised tank. Furthermore the discolouration will appear on the inside of the cabin as well as the outside which is a shame as most customers like to retain the nice light pine look inside.
The intake of moisture into the wood causes swelling and some distortion. This can give rise to assembly difficulties if the joints are too swollen to slot easily together. It is considered best to let pressure treated logs stand for several weeks before attempting to use them, thereby giving the wood a chance to dry out and return to correct dimensions.
Pressure treatment is not a waterproofing treatment, so once the cabin is built the wood will continue to take in moisture causing it to expand and maybe warp. It will still need a high quality brush on treatment afterwards to prevent these problems.
The appearance of pressure treated wood will become grey in a relatively short time and normally requires a brushed on treatment to decorate and restore appearance.
High quality weather protectors require two coats on new wood and will usually provide five years protection before a re coat is necessary.
If the cabin is going to need to be decorated anyway, it is far better to do it right first time, after construction and at far less cost.
