Timber is a natural product that reacts to its environment. Wet, dry, hot, windy, humid, sunny, overcast or cold. All types of weather can affect timber—however, changes in the woods surrounding environment cause most visual timber problems. Wooden fencing materials can warp, twist, shrink, expand or develop shakes (splits in the wood) and, of course, rot.

Visual Timber Problems

All of the visual problems with wood are usually caused by moisture movement into or out of the timber. Generally, the faster the wood’s moisture content changes, the more likely that one or more of the problems mentioned above will occur. See our pages on Looking after Pressure Treated Fencing and Crestala Gate Care Information for ways to alleviate some of these problems.

Pressure-treated timber is more prone to visual problems during the first few months. The pressure treatment process forces treatment fluid deep into the wood. This makes all treated timber even more susceptible to natural movement issues as the wood dries out initially. This initial movement is not considered to be a defect. For more information on the treatment process, see our page on Timber Pressure Treatment.

Whether treated or not, all softwood timber will have some natural movement or shaking (cracks in the wood) as the timber expands and contracts during the regular annual weathering process. However, these problems do not usually affect the structural integrity of the wood and will mostly disappear when cooler, moist weather returns. As we have no control over the environment, this natural movement is not considered a defect

Whilst moisture movement is the main cause of timber movement issues, it is not the only one. Stresses and strains put into the wood as it grows can be released after the wood is sawn and ready for its intended use. These may show up quickly or only become apparent over time.
A few years ago, we were asked to look at a post we had supplied for a fence in Crowborough. The post was in its third summer and had been fine up to this point. Then, it had decided to twist nearly 180 degrees like a corkscrew for no apparent reason, breaking the arris rails in the process. The other posts in the fence were OK. I could find no reason for this strange occurrence. Something this severe is rare, but timber can sometimes do surprising things.
There is no way to tell which wood will be affected, and it is not considered a defect.

Wood Rot

Wood rot on fencing and gates is invariably in areas that tend to stay wet or damp. On fencing, this is usually post bottoms, gravel boards, the lower edge of the fence, end-grain and joints or attachment points. Gates should not touch the ground, but they have many joints and end grains that can allow water ingress.
Posts are naturally worst affected as they are sunk into the ground. However, posts that have rotted at the bottom can be repaired with concrete repair spurs, which can extend the life of your fence.
The Association of Fencing Industries, of which Crestala is a member, is currently working with its members and the Wood Protection Association to improve the treatment of wooden posts. Click here for an update on progress at the AFI wood conference.
There are alternatives if you are considering replacing your fence and are worried about wooden posts rotting off. Mortised concrete posts are available for closeboard and palisade fences or slotted concrete posts for panels. For those who don’t fancy having concrete posts around their garden, there is the versatile and increasingly popular metal DuraPost with its long manufacturer’s guarantees.

What You Can Do

You cannot stop wood from being wood. Any wooden fencing, decking or gates will have some of the issues mentioned above to a lesser or greater degree. However, we can minimise the risk of having severe problems. How you prepare and maintain your timber, whether fencing or gates, can help. Over the last decade, the maintenance and decorative treatment options for wooden fencing have changed. Many more traditional treatments, like Creosote and CCA, have been banned or their use restricted for health and safety or environmental reasons. Our pages on Looking after Pressure Treated Fencing and Crestala Gate Care Information have information and tips to help you choose from current options.

Please read our other timber care information sheets (links below).