You should ensure that adequate space is left on all sides of the cabin to allow you to apply the annual treatment and perform any maintenance required.
Your log cabin is untreated. It is therefore vital to treat your log cabin as soon as possible after assembly with a high-quality wood preserver.
We would recommend applying several coats and try get a good thick layer to the bottom few logs on each side and around all log joints.
If you wish to treat your log cabin with a paint, you may want to use a clear preserver as well as the paint. Speak to the paint supplier / manufacturer for more details.
You then need to re-treat the garden building regularly (typically once a year) to ensure the logs and thoroughly protected.
We would also recommend treating the inside of your log cabin as well as the outside.
You will also want to ensure that there is no debris build-up on the roof of your cabin, and that no branches are touching the felt. This can degrade or damage the felt and lead to water pooling or water ingress.