Georgia amends IRC R502.6 (Georgia DCA amendments to the 2018 IRC), which governs how the ends of joists, beams and girders are supported.
Minimum bearing lengths
- On wood or metal: not less than 1-1/2 in (38 mm).
- On masonry or concrete: not less than 3 in (76 mm).
The trap is using the 1-1/2 in wood or metal figure on masonry. A floor joist on a masonry wall needs 3 in. The 2 in figure is the sill plate thickness, not a bearing length, and 1 in has no basis in the section.
Direct bearing or a 2 in sill plate
On masonry or concrete, bearing is direct, or a sill plate of 2 in minimum (51 mm) nominal thickness is provided. A girder on a CMU pier bears directly on the masonry or on a sill plate at least 2 in nominal. A 1 in nominal plate is too thin, and a fiber expansion strip is not mentioned.
Other permitted supports
- Approved joist hangers.
- For joist ends, a 1x4 ribbon strip nailed to the adjacent stud.
The ribbon strip supports joist ends at studs. It is not a bearing surface on masonry.
Mixed supports
Check each end against its own support. A beam on a steel ledger at one end and a brick pier at the other needs 1-1/2 in on the steel and 3 in on the brick. The traps: 1-1/2 in at both ends puts the metal figure on masonry, 3 in at both ends overstates the metal requirement, and 3 in on steel with 1-1/2 in on brick swaps them.
Spotting the one that fails
- 3 in of direct bearing on a concrete foundation wall: permitted.
- Approved joist hangers: permitted.
- A 1x4 ribbon strip nailed to the adjacent stud at joist ends: permitted.
- 1-1/2 in directly on a brick wall: not permitted, because masonry needs 3 in.