Professor Miller – A Respected Civil Engineer
NOTE – Professor Miller is a respected civil engineer having taught at the University of Washington for over 40 years. Here is what he has to say about Sing Log Homes…
A Testimonial from Professor William Miller – I became familiar with your mill Practice some two years ago. By way of background, I am a civil engineer. I taught in that capacity at the University of Washington for more than forty years. Among my many subjects, I was involved with laboratory testing of construction materials, not the least of which was wood. I also taught wood design involving plywood, heavy timber, posts and beams, and dimensional lumber all the way down to the 2 x 2. In fact, wood is my hobby. Now, in retirement, I spend long hours in my home workshop. My point in writing is to inform you of my observations regarding your products.
I first consider your raw material – small diameter logs, mostly cedar, cut from trunks that generally taper down to less than a five inch diameter. Because of size and disturbing taper they are rejected by all other saw mills, and, at best have been utilized to a small degree for pulp. Normally these tree stems have been culled from the log stacks in the woods and regarded as waste. You are to be commended for taking these castaways and turning them into useful products. You have certainly become popular in the eyes of conservationists and environmentalists.
One would surely be mistaken to arbitrarily assume that the quality of wood in these “rejects” is lacking. Furthermore it would be incorrect for one to broadly label these poles “fourth” or “third” growth. I have personally visited your log yard and mill. I observed that the great majority of your poles are over 50 years old. They are slow grown. The rings are close, exhibiting about 50% summer wood. Through a cross-section the pith appears as a pencil point. Collectively, the cores appear to be highly invulnerable to fungi. When the logs are quarter-sawn through the pith and subsequently composed in your mill, cross-sections reveal very nearly 100% heartwood. I should also mention that the small knots are extremely tight. They do not diminish (and might even prove to enhance) the strength.
They provide a special beauty to exposed surfaces, unique and non-existent in conventional softwood lumber. In short, I recognize a high-quality material, one that has gone unused for too long, left only to eventually perish in the woods.
You take a log and reconstruct it – something that can now be done through the advent of quality glues. I now consider your range of potential products.
One raw log, having been lathed to a constant diameter, then quarter-sawn twice through the pith, then reorganized into a square cross-section, and finally glued produces a 4 x 4 “post”. Advantages? All four sides reveal a highly desirable close vertical grain. Quality control at the mill minimizes initial imperfections (such as shake, splits, etc.). There will be no further “in-service” splits. I will return to this matter shortly. The method of cutting and bonding induces stability. No cup, minimal (if any), bow, crook, or other types of warping. The quality of the wood remains high, in appearance, stiffness, and strength.
In wood construction, considering all of the various grades of dimensional lumber, the ultimate is designated as “appearance- structural”. The word structural can only be assigned to “stress-rated” lumber. The ultimate designation can only be achieved pending laboratory determination of mechanical properties and publication of allowable stresses. If, or when this is done, I’m convinced that your 4 x 4 “post” would successfully compete as an “appearance-structural column”.
You take four or more quarter-sawn lengths and bond them together side-by-side, keeping the wanes on the down surface. This you should declare to be a “sing-plank”. We know that the plywood industry produces a product described in part as “one side good”. I submit that your plank is “one side excellent”. There are main non-structural applications for your plank – yard furniture, benches, paneling, etc. I have personally built a kitchen bar. I also built a 24 x 24 foot, steel-framed carport deck. Decking spans were nominally 5 feet. My original design required (and specified) standard “selected decking”, hem-fir, 2 x 6 tongue & groove (1 1/2″ x 5 1/2″), random lengths. After plan review and issuance of the permit, I switched to 2 x 8 cedar sing planks (1 7/8″ x 7 1/2″). The deck was fully approved on final inspection. The deck surface is absolutely beautiful. Presently, I carefully observing the surface response to the rigors of very wet water exposure. I see the anticipated expansion due to moisture content but nothing excessive. No buckling, no cup, no splits – but, will splits develop with shrinkage from summer heat? The nature of the cutting, the log reconstruction, the gluing is such that they will not. I have conversed with experienced and reputable lumbermen in this area on this very subject. All agree, as do I, that the greatest single quality of the sing plank is the absence of “in-service” surface or end splits. So far as I know Mine is the first and only sing plank carport deck ever to have been constructed. I am well pleased.
If you take two sing planks and glue the wane-side faces together, the result is “sing beam”. All four sides meet the requirements of “appearance” grade lumber. Perhaps it is only a matter of time and laboratory testing for you to be able to present this as an “appearance-structural beam”. I certainly encourage you to do so.
You take the sing planks, separate the wane-side surfaces with glued-in 2 x 4 spacers, and you define the product as a “singlog”. Obviously you do so it is presently employed in the competitive arena of log house construction. May I suggest you think about renaming it the “SingTimber”? Thus, to the convenience and benefit of the consumer all of your products would be in full concert.(and competition ) with the rest of the softwood lumber industry.
William M. Miller
University of Washington
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