In conventional light-frame construction, what is the minimum girder size for spans of 6 ft or less?

In conventional light-frame construction, the minimum girder size for spans of 6 feet or less is typically a 4" x 6". This sizing is based on standard building practices that ensure appropriate load support and structural integrity while minimizing material use.

The choice of a 4" x 6" girder is sufficient for the relatively short spans of 6 feet or less, providing adequate support for the loads typically encountered in residential and light commercial buildings. This size ensures that the girder can handle the demands of the structure, including dead loads and live loads, without excessive bending or deflection.

Other sizes listed, such as 2" x 6", fall short in terms of structural capability for bearing loads over spans, while the larger sizes like 6" x 6" and 8" x 6" would be more robust than necessary and could lead to over-engineering and unnecessary material costs for such short spans. Adopting the correct girder size is key to balancing structural performance with material efficiency.