Bigger Isn’t Always Better When It Comes To Sawmilling Cedar Trees

Currently, I am working with a green builder in St. louis on a project where we are using eastern red cedars from the site to make siding for the house. A couple of years ago, I worked on the Tyson Living Learning Center, which is one of the “greenest” buildings in the country, and I also milled cedars for the siding on that building. In total, I have milled hundreds of cedars logs and have learned a lot about them.

Bigger logs weren't always better for making the eastern red cedar siding for the Tyson Living Learning Center.

Cedars are light, easy to cut and usually fairly small. I was excited to cut the cedars at Tyson because many were quite big. A few even maxed out the 30″ bar on my chainsaw when I felled them. The cedars on my current job are not as big, but are actually better because of it. It seems counter-intuitive, and for all of the milling I normally do, it is. I always want the logs big. In hardwoods, big logs have more clear, high-grade wood – but, not cedars, or at least the bottom logs of big cedars.

Back of the Tyson Living Learning Center shows how smaller pieces were used. (Architect: Hellmuth & Bicknesse / Builder: Bingman Construction)

Here is the problem. Big cedars have big trunks that tend to have two major defects. The first is bark inclusions. As cedars get bigger, they get more furrowed near the base. These furrows turn into wrinkles and then the wrinkles turn to big waves. As these waves increase in size they roll over nearby bark and seal it in the log. The log keeps getting bigger, but this bark works like a perforation in the lumber and makes the lumber fall apart, similar to ring shake. It is very frustrating because you can have a big wide board and then it just falls apart in your hands.

This one shows a long bark inclusion on the outside.

Old big cedars from Tyson show deep bark inclusions. Some go to the middle (pith).

This inclusion is big, with dead knots. A real jackpot!

The second defect is dead branches and knots. If the tree grows in the open this is usually less of a problem because the lower branches don’t die off. But, in trees growing in the woods or in tight proximity to one another the lower branches do die, and since they are cedar and last a long time outdoors, they only very slowly drop off. While the branches are still attached and dead, the tree keeps growing and tries to cover them over. What ends up happening is that the lumber has knots in it that will fall out. Even if they don’t fall out right away, they will eventually. This is a problem when running cedar through a moulder to make siding, since the knots will fly out and at least clog the machine.

A dead branch leads to this loose knot that will fall out.

A live branch leads to this nice tight knot that will not fall out.

When working on the Tyson project (which had big logs) a good percentage of pieces would have a knot fly out in the moulder and make that part unusable. Luckily, there were a lot of windows and other places to use short pieces. The logs that I am working on now are from younger logs and have live branches along most of the stem. The average diameter is probably 10″ on the skinny end, but most of the lumber is sound, which will yield more than 20″ logs with only half of the wood being solid. When I look back on the Tyson project, there were several logs that weren’t even worth the time to mill since they were so full of defects, but it is hard to pass up a 18″ cedar log without cutting it first. On the upside, cedar burns really hot, but that is for another post.

This is what we are looking for – all the knots are sound and the log is round with no inclusions.