Weyerhaeuser is occasionally asked for guidance with floor joist design relative to non-bearing interior partition walls. Specifically, whether perpendicular non-bearing walls should be accounted for in member design.
The International Residential Code (IRC) dictates residential floor design live loading as either 30 psf (pounds per square foot) or 40 psf, depending on whether the area is sleeping or non-sleeping use.
Little direct code guidance is given for design dead loading, although code commentary (paragraphs R301.4 and R502.3) is useful. Design dead load is described as the weight of all permanent construction such as floors and permanent partitions. Perpendicular partition walls are not directly addressed.
Typical interior non-bearing partition walls oriented perpendicular to the floor joists are often ignored by designers for floor joist design. This design choice can be due to several reasons such as:
- Inclusion of additional dead load in the floor load to account for a portion of additional load from perpendicular partitions
- Live load in floor area covered by the partition wall cannot exist
Ultimately, the designer must be aware of unusual conditions that warrant special consideration and account for them. A glass block shower wall may be triple the weight of a typical partition wall, as would a marble tiled bath wall, as examples.