- A lay-on gable frame is typically connected from the top during truss placement, but after sheathing is installed, this connection is no longer visible for the building inspector to verify.
- This creates a need for an alternate connection that is visible from below.
- The connection described in SRR 1505-02 is a simple, cost-effective, toe nail connection between the lay-on gable frames and supporting truss system that is visible after sheathing is installed.
- In designing the connection, assumptions were made with the intent for the connection to be applicable to a majority of situations encountered.
- It is the building designer’s responsibility to ensure that the assumptions listed are equal or conservative to project requirements.
- The following steps will assist the designer in verifying whether this connection is applicable for the project.
- ASCE 7-10 is referenced by IBC 2012 and 2015
- Project specific loading that does not exceed 5 psf dead load in total is acceptable
- The project must meet the criteria for C&C determination of wind pressures including:
- The building must not be subject to across wind loading, vortex shedding, galloping, or flutter
- The site must not be subject to channeling effects or buffeting due to upwind obstructions
Verify Project Dimensions
- The project should be a regular shape - i.e. a building without irregularities in spatial form per ASCE
- See ASCE 7-10 Table 12.3-1 or 12.3-2 for criteria
- Mean roof height should be no more than 30’
Verify Project Attributes
- Values more conservative than those listed (e.g. lower wind speed, exposure category) are acceptable
Verify Connection Location
- Trusses and lay-on gable frame members may be spaced a maximum of 24" o.c.
- The connection location analyzed represents the largest tributary area on a typical layout
- Alternative locations are acceptable provided that the tributary area does not exceed that shown
Verify Materials and Fasteners
- Framing material must be SPF (Specific Gravity = 0.42) or better
- Nails must be 10d (0.131 x 3.25”) or better
- Better materials and fasteners will increase the capacity of the connection and make the connection more conservative.
- Ensure fasteners meet spacing requirements:
- Supporting truss
- Edge distance = 4D (4x0.131” = 1/2”)
- Row spacing = 5D (5x0.131” = 5/8”)
- Lay-on gable
- Edge distance = 1.5D (1.5x0.131” = 3/16”)
- Row spacing = 1.5D (1.5x0.131” = 3/16”) and ½ spacing between rows (0.5x0.655” = 5/16”)
- Supporting truss