Why does wood split and crack?

It’s a good question and it’s one that we get a lot. Wood is a natural product and it reacts to its environment in ways that you don’t see with vinyl and iron.

When freshly cut wood dries it leaves splits in the wood called checks. Like most materials wood expands when it’s wet and contracts when it dries. The checks are caused because the wood doesn’t dry uniformly. Checking is extremely common and unavoidable.

It’s very natural for wood to split as it dries.

When your fence is installed, the same dynamics are at work so there will be further splitting as it ages. The more variable the weather is the tougher it will be on a wood fence. Alternating rainy and dry spells, large temperature swings, and the march of Canada’s seasons will all take a toll on wood. The underlying process is always the same: the wood will expand and contract, and it will do it at different rates because of the differing densities in the lumber. This will cause splits.

What can I do?

Boards will generally split before posts as the fence ages because they are thinner. You can replace them as needed, or do it a section at a time to maintain a consistent appearance. Depending on the type of fence, this can be quite easy for anyone who’s handy with a toolbelt and hammer. Posts are obviously a bigger deal to replace but here’s the good news: they can handle a lot before the structural integrity of the fence is compromised. Splitting is actually desired because it keeps the posts from warping and pulling the fence out of line. And they aren’t as visible as the boards so the aesthetic damage is minimal.

Pro tip

Make sure you know what you’re getting before you buy. Wood is going to change from the day it’s installed. Many people like this, and believe it adds to the charm of their project. They’re also prepared to do some maintenance as the seasons pass. If this sounds like you, terrific. If it doesn’t, a vinyl or iron product might be more to your liking.