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Frequently Asked Questions
General
What is the difference between balanced and unbalanced glulam beams?
Glulam beams are typically designed with the highest quality laminations placed in zones of maximum expected
flexural tension
stresses. A somewhat lower grade can be used to resist
flexural compression
stresses with no reduction in beam capacity.
Consequently, lay-ups are divided into two categories:
balanced and
unbalanced
(See figure). Balanced beams are typically
used for continuous-span and cantilevered applications where both the top and bottom of the beam will be subject to
flexural tension. Unbalanced beams are preferred for simple spans, because they use lumber resources more efficiently and
are consequently more economical than balanced beams. Unbalanced beams can also accommodate short cantilevers (up to about
20% of the main span).
To avoid improper installation, glulam beams are distinctively marked with a “TOP” stamp. Protective wrappings on glulam
beams are also typically stapled on the top face of the beam to avoid damaging the faces that will be exposed to view in the
finished structure.
Unbalanced layups are optimized for simple spans, and balanced layups are optimized for multiple spans. Letters symbolize
relative quality of laminations (A represents highest quality, C represents lowest quality in lay-up)
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