Posts Tagged with laminated curves

Nice Curves

Posted on July 22, 2007 by Whit Holder

One way to add beauty and visual interest to a timber frame is to use curves or arches in the design. Although frames have been built with curved members for hundreds of years, a well-proportioned pair of arched braces still communicates a sense of gracefulness and strength.

There are three types of curved timbers: sawn curves, bent stock, and laminated curves.

Sawn curves are curved stock sawn out of wide straight timber, such as an 8" wide arch sawn out of a 14" wide beam. This is the weakest type of curved member because the grain is not continuous and the pith of the tree is often severed by the saw, giving the piece a strong tendency to split apart. Free-of-heart timber is desirable for making these pieces.

Bent stock is stock that grew in a natural curve or bend in the forest. Bent stock is much stronger than sawn curves because the grain has grown in a curved form, and the carpenter only needs to saw the waste wood away to get a beam that possesses the same curve that it had as a log. Most of the grain remains intact and therefore most of its strength is retained. During conversion, the carpenter should make an effort to follow the log's inherent curve.

Laminated curves are made from individual boards that are glued together, bent to a specific desired shape, held under pressure until the glue sets, and then planed to a consistent thickness on the sides. Advantages to lamination include the wide range of radii that can be produced, the stability gained by using kiln-dried lumber, and a grading system that allows strength values to be assigned.

Sawn curves are commonly used decoratively, but rarely in structural applications, unless the curve is slight. Bent stock is commonly used in English or old-world European framing styles, which have a rich history of using natural curves. In fact, it is very difficult to build in these styles without using bent stock. Notice the natural curves the next time you see an old-world framed house.

When strength and stability are in question, laminated curves are the best choice. They provide consistent shapes, a clean, contemporary look, and can be grain-matched to hide the lamination lines, making the piece look more like one solid curved timber.

Whether it is a medieval cruck frame, a soaring gothic arch, or a book-matched pair of naturally curved braces, properly used curves and arches are visually appealing and enhance a timber frame's appearance with strength and beauty.

Tagged: timber frame, timber frame design, post and beam, arched braces, natural curves, laminated curves, curved timbers  |  0 comments