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The Guide to Check Posts and Splits

Oh no, my post has a crack! What should I do and is this something to worry about?

check postSplits” and “checks” as they are commonly called in the industry are a normal and unavoidable part of owning an outdoor product made from pressure treated Southern Yellow Pine. A “check” is defined as a separation of the wood, normally through the rings of the lumber and is the result of seasoning. These “splits” and “checks” are part of the nature of lumber and are an unavoidable part of the drying process. An example of a normal “check”, is pictured here to the left.


Yellow Pine is a hygroscopic lumber, this means it retains moisture. Most people are surprised to find out that more than half of the weight of a living tree is water. However, we use a #1 Grade Pressure Treated Lumber that has been kiln dried. This means we use a quality lumber with low knots and defects; it has been pressure treated, then followed by a drying process to bring the moisture content down to about 15%.
What often happens is once you’ve received your structure and install it, you probably notice the nice finish and smooth lumber. This is because we keep most of our nice kiln-dried and smoothly, milled lumber indoors and away from additional rain and moisture. However, once your structure is re-introduced to the outdoors with external effects, such as humidity, rain, and the sun. Those external effects begin to interact with the lumber and the moisture content begins to change.

So, what causes the check?

As a result of the change in moisture, “checks” and “splits” begin to occur due to the outer surface of the lumber drying and shrinking faster than the inside. Water-in-BeamThe swollen, wet center of the lumber holds solid and the shrinking exterior gives way and splits open. You can see the difference between the wet center and the outside drying in the photo to the right.
Although an aesthetic issue “checks” rarely diminishes the service life of properly treated lumber. Most often, as the post or beam dries to an equal amount of moisture throughout the board, these “checks” and “splits” will decrease in size or disappear over time.

What should you do?

When a check occurs, grab the stain provided with your structure, and touch up the exposed lumber inside the “check” or “split”. By protecting all exposed areas of the wood, this will help keep your structure looking its best and protect the newly exposed wood.
So, sit back and enjoy what many have called the Song of the Lumber, these cracks will pop and make noise as they occur. Just know this is simply the nature of lumber and will add to the character of the structure.

Looking for more advice on an outdoor structure? Read more of our other blogs! Also, learn more about how to clean your structure.