At Timber Masters, our timber quality is our highest concern. The timber we use is Western Canadian Douglas Fir slow growth timber. This essentially means that the trees grow slower in the colder northern areas, thus making a tighter grain which is more stable, as the tree takes longer to grow versus faster growth wide grain. This timber is harvested for quality and stability and is not easy to find.
What We Look For When Choosing Timber.
1. Timber Grade
2. Timber Cut
3. Moisture Content.
1. Timber Grade
Everyone sells "#1 grade" timber.. but the best timber is actually called “select structural”. All our timber is #1 or better and most of our timber meets the “select structural” grading requirements.
Some of the things that are graded are the size and location of any knots..(places where branches used to be), length of any splits, holes or honeycomb and many other small details.
The term 'clear' means no knots.
2. Timber Cut
Starting with the FOHC (free of heart center) of the log is the number one step.
Some companies except the standard of “boxed heart” cuts. It means smaller trees can be used where the center of the tree takes up a larger percentage of the log as a whole. But if you see the photo below, you will see that they check (or crack) excessively.
As mentioned at the start of this article, tight grain is more stable as the tree takes longer to grow. “Vertical grain” is the best timber for slabs etc, and is also the most expensive as you can only get so much vertical grain from a single large tree.
3. Moisture Content
Moisture content is how wet the timber is on a percentage of 0 to 100. Fresh cut trees can be 50 to 60%. This is wet. Timber that is cut and left to season normally does not get much less than 15% or “equilibrium moisture”, meaning the average relative humidity of the air.
When we kiln dry timber for interior timber elements or box beams we ensure the moisture content is 10 -12%. For timber frames kiln drying is an option. Because unless specialized kiln drying occurs, it's usually only the outside 1.5 inches of the timber gets fully dried to the specification requested. Still, this can help to dry the wood and make it less susceptible to checking (cracking) or movement Kiln drying full timber frame timber can help to “pre-check” the timber.
However, if you are using a high grade wood like FOHC tight grain, the frame changes little and the timber frame joints actually become tighter over time.
Therefore non kiln dried but “seasoned” frames are pretty much the industry standard.
In conclusion, the cut and quality of the timber, (as well as the joinery methods and finishing techniques) will all become very highlighted over time. We are concerned with not only how the frame looks when it leaves the shop but that it will continue to look as best as possible over time.