# Do Knots in Cedar Cause Structural Weakness?



## Furnitude (Oct 18, 2008)

I'm making a set of Adirondack chairs and this is my first time to really use Western Red Cedar. If you look at the crude drawing, I've tried to show the location of a knot in one of the boards I'm going to use for arms. Will a knot in this location cause structural weakness? Thanks for any comments.


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## RyanHaasen (Oct 29, 2011)

Yes, I think it will, especially if it has a hollow spot.


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## Doss (Mar 14, 2012)

Yes. If the knot is that circle and it takes up that much space, it's going to be a problem. The knots usually fall out of WRC.

If the wood were really thick and the knot pretty shallow, possibly not. But, it looks like, in this case, that it's going to be an issue if it gets any load applied to it.


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## Blackie_ (Jul 10, 2011)

I'm curious if CA wouldn't solve that problem, I know it would keep the knot from falling out. One other thing you might try is making a western sawdust paste using wood glue and fill in the voids also blending.


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## gfadvm (Jan 13, 2011)

I learned the hard way that knots at stress points are the weak link and will fail in a load bearing situation. In my tall chairs of recycled Doug Fir, I have learned to avoid putting knots in the legs or seat slats. I'm referring to full thickness knots of significant diameter (3/4-1").


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## ArlinEastman (May 22, 2011)

It will cause a weak point, however, I do know of several guys that have drilled them out and put in epoxy in the hole with some ceder dust.

Arlin


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## Bearpie (Feb 19, 2010)

Yes, definitely it will weaken the area. could you possibly switch the board around and put the knot on the wider part of the board?


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## MonteCristo (May 29, 2012)

Curious that someone in Tennessee is using Western Red Cedar (WRC) which is native to my neck of the woods. This wood is weak structurally to begin with, which makes it even more important that a knot like the one you show should be avoided.

In case you aren't familiar with WRC, it is very easy to crush so cutting motises and the like requires really sharp tooling. It is quite rot resistant but that comes at a price - depending on who you talk to it's dust is toxic to very toxic. Some people out here even get an alergic reaction just handling it, although that is pretty unusual. Old growth WRC is a much better wood than second growth stuff, much deeper color to the heart wood and very stable with fine annual rings. Much more rot resistant too I suspect than second growth.


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## bondogaposis (Dec 18, 2011)

I would be looking for another piece of wood for that.


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## rrdesigns (Sep 4, 2009)

And some ears, legs and a tail and you can use that piece for an elephant. Waste knot want knot.


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## tomd (Jan 29, 2008)

I would be leary of using it.


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## woodtools (Feb 18, 2012)

A western red cedar knot as you display in the drawing has no structural value. If you were to think about your adirondack chair arm as having a hole in it the size of the knot, you will answer your own question. As with western red cedar, used in outdoor applications, the knot as described will fall out in 8-12 months
Good luckwith what will be a beautiful piece of outdoor furniture.


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