Design Solutions - Spring 2008 - (Page 53) Plainsawn Lumber result of plain sawing. Quarter sawn lumber, on the other hand, almost always has a finer grain figure. In some woods, like Maple, quartering results in a very “vanilla” appearance, almost eliminating the beauty of natural wood. The term “rift” is most appropriate only for red and white Oak. When Oaks are quarter sawn, they often exhibit the outstanding flake or ray figure sometimes called “tiger Oak” on antique furniture. If that flake figure is not desired, quartered materials are sorted for the rift characteristics. CoSt and Size d i M e n S i o n a l S ta b i l i t y Riftsawn Lumber Quartersawn Lumber Page 16, Quality Standards Ilustrated Heartwood, Sapwood and Sawing MetHodS One growth issue which influences species selection and specifications is the issue of heartwood versus sapwood. The heartwood is the older part of the tree, and is usually darker in color. The lovely dark color we prize in Walnut is the heartwood. Sapwood, on the other hand, is just under the bark layer of the tree, still carrying nutrients up the trunk of the growing, living tree. Usually lighter in color, it is also prized in some specifications, such as those calling for select white Maple or select white Birch. All that wood has to come from the sapwood area of the log. The most common type of sawing is called plain sawn or flat sawn. Page 16 shows a typical figure on plain sawn lumber. That beautiful cathedral effect you’ve come to expect in fine Walnut or Cherry is a The most frequently asked questions about solid wood revolve around cost and size. Cost is controlled by availability, which varies from year to year, and even from season to season for some species. The Comparative Table of Wood Species (Page 17 in the 8th Edition Quality Standards) looks at costs of lumber and some related plywood, using natural Birch as the benchmark. Perhaps the most important factor to remember is: don’t spend a great deal of time or effort trying to control project costs by changing species time and again. Studies have shown that lumber and panel products traditionally account for only about 10-15% of project costs. Saving 10 cents a foot by asking your customer to settle for a second-choice species is hardly worth it in the overall scope of the work. Practical widths and lengths must also be considered when developing elements which will need solid lumber members. They are shown on the Comparative Table of Wood Species on Page 17, with the very important footnote (Footnote 2 at the bottom) that only 10% of an order can be expected in long lengths. All woods are affected significantly by moisture and to a lesser degree by heat. Lumber swells and shrinks primarily in two directions: thickness and width. There is insignificant change in length. The changes in dimension due to moisture vary with different species, thus influencing the selection of lumber to use and the design elements. Prevention of dimensional problems in architectural woodwork products as a result of uncontrolled relative humidity is possible. Wood products perform, as they have for centuries, with complete satisfaction when correctly designed and used. Problems directly or indirectly attributed to dimensional change of the wood are usually, in fact, the result of faulty design or improper humidity conditions during site storage, installation, or use. Figure 100-03, page 24, Quality Standards Ilustrated Spring 2008 I DESIGN SOLUTIONS 53 How to Select Solid Lumber Density has a good deal to do with the strength or hardness of the species. The Comparative Table of Wood Species has a column on hardness that can be consulted if that’s important to the job. Finally, dimensional stability must be considered when wide lumber members are a part of the design aesthetic.
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