Manufactured Ply: Wednesday's Word(s) Of The Week

Manufactured plies cover the wide members of this pergola

In last week's entry, it was described how a combination layup can be used to make glulam beams wider than 10½", and that it was one of two methods. The second method is to use Manufactured Plies.

Manufactured plies are essentially extra large lumber made out of glulam, so that it is no longer limited to 20' long and nominally 12" wide. For example, a standard 8½" x 22" x 40' long glulam beam can be sliced vertically into five
pieces. Each piece is 1½" thick, 22" wide, and 40' long… and can be used as a single ply in a wide glulam beam.

End cut of glulam made entirely with manufactured plies

There is more work and waste involved in making a beam from manufactured plies than a combination layup, so it is only occasionally used. Sometimes a single manufactured ply is added to the face of a combination layup to avoid plugging the face. Or, for complicated parts like a spiral, manufactured plies are easier to handle than the multiple boards in a combination layup. Note that when you use a manufactured ply there will be glue lines on all sides of the glulam made from manufactured plies. 

*Wednesday's Word Of The Week is a feature on Unalam's Wood Times Blog. Each Wednesday our structural engineer, Rik Vandermeulen, will discuss a new term associated with glulam manufacturing. He will do this until we run out of words. If there is a timber or glulam term that you have heard of and want to know more about, let us know in the comments.