Timber Checking

Wood is a natural material prone to change and variation. Like people, no two trees are exactly the same, and no piece of wood from two individual trees will ever look perfectly identical. The nice thing about wood is that pieces of timber will always complement each other even if they don’t precisely match. Some clients without much experience working with wood struggle with the idea that wood is a material that can be shaped and stained, but that can’t be reproduced identically each time, like metal or plastic.  Wood will always have some degree of natural variation that we can’t control. That’s one of the great things about wood: every piece of timber is unique! So everything you build with timber will be unique and specific to your structure.

Checking in an Oak Timber Frame

Besides species, other characteristics that can make timbers look different are natural coloration and grain variation, density of the wood fibers, portion of the tree from which it was cut, all affecting how a piece of wood takes a stain.

Checking is another aspect of the natural variation of wood that can be unpredictable and hard to control. Checking can be greatly misunderstood by the wood novice. People see a crack in the wood and think, “It’s broken!” Most likely, the wood is not broken and the check in the wood is not compromising the structure’s stability or integrity in any way.

At Vermont Timber Works, we engineer our structures to accommodate the natural movements of the wood as it dries and ages, including checking and twisting. Sometimes it won’t do either, and sometimes, a year or so after construction, you’ll see checks developing in the wood as it dries and shrinks with age.

Checking in Hand Hewn, White Pine Timber Frame

We know this is normal behavior for wood and it further individualizes your structure and your timber beams and trusses, providing that rustic antique look many people enjoy. For people who really don’t like the look of checking, or are still concerned about how checks affect the wood quality, there are species choices that are less prone to checking. You can also use “free of heart” timbers which are less prone to checking than heartwood. Some species like Oak for example, are very prone to checking and should be avoided if you don’t like that look.

Slight Checking in a Hemlock Timber Frame Barn

You could also use weathered wood, which has been left out and has dried enough so the appearance won’t change much more over time. A similar route would be to use reclaimed wood which, having been used to build a barn or other structure a long time ago, would be very dry and its appearance wouldn’t change much more over the years. If you really can’t stand the thought of checking at all, then you can always opt for Glulam material instead, which will ensure that the beams and arches will look the way they did on the day they were installed.

In some cases, extreme checking can be a cause for concern, such as when the crack extends to the other side of the timber and becomes a split. Split timber is considered defective and if there’s a split in a beam or a post, it should definitely be inspected.

Do you have a question about Timber Checking or want to know more? Submit a question to our ask the expert’s page, or comment below!

About the Author