Wood Construction Connectors General Instructions for the Designer
These general instructions for the designer are provided to ensure proper selection and installation of Simpson Strong-Tie Company Inc. products and must be followed carefully. These general instructions are in addition to the specific design and installation instructions and notes provided for each particular product, all of which should be consulted prior to and during the design process.
- The term “designer” used throughout this catalog is intended to mean a licensed/certified building design professional, a licensed professional engineer, or a licensed architect.
- All connected members and related elements shall be designed by the designer.
- All installations should be designed only in accordance with the allowable load values set forth in this catalog.
- See page 10 of the Wood Construction Connectors Catalog for allowable load information.
- See page 267 of the Wood Construction Connectors Catalog for connections with simultaneous loads.
- Loads are based on the 2015/ 2018 NDS and AISI S100 if applicable, unless otherwise specified. Other code agencies may use different allowable loads.
- Unless otherwise noted, loads include Load Duration, Group Action and Toe-Nail factors from the NDS as applicable. The application of additional adjustment factors shall be by the designer. Duration of load adjustments as specified by the code are as follows:
"PERMANENT" — 90% of the design load.
"FLOOR" and "DOWN" (100) — no increase for duration of load.
"SNOW" (115) — 115% of design load for two month duration of load.
"ROOF LOAD" (125) — 125% of design load for seven day duration of load.
"EARTHQUAKE / WIND" (160) — 160% of design load for earthquake/wind loading.
- Unless otherwise noted, wood shear is not considered in the loads given; reduce allowable loads when wood shear is limiting.
- Simpson Strong-Tie strongly recommends the following addition to construction drawings and specifications: “Simpson Strong-Tie® connectors are specifically required to meet the structural calculations of plan. Before substituting another brand, confirm load capacity based on reliable published testing data or calculations. The Engineer/Designer of Record should evaluate and give written approval for substitution prior to installation.”
- Verify that the dimensions of the supporting member are sufficient to receive the specified fasteners, and develop the top flange bearing length.
- Some catalog illustrations show connections that could cause cross-grain tension or bending of the wood during loading if not sufficiently reinforced. In this case, mechanical reinforcement should be considered.
- The allowable loads published in this catalog are for use when utilizing the traditional Allowable Stress Design methodology. A method for using Load and Resistance Factor Design (LRF D) for wood has been published in ASTM D5457. A method for using LRF D for cold-formed steel has also been published in the AISI S100-16. When designing with LRF D, reference lateral resistances must be used. Contact Simpson Strong-Tie for reference lateral resistances of products listed in this catalog. For more information, refer to the 2015/2018 NDS Appendix N, which contains a conversion procedure that can be used to derive LRF D capacities.
- For joist hangers, Simpson Strong-Tie recommends the hanger height shall be at least 60% of joist height for stability against rotation while under construction prior to sheathing install.
- For cold-formed steel applications, as a minimum all screws must comply with Society of Automotive Engineers (SAE) Standard J78, Steel Self-Drilling/Tapping Screws, and must have a Type II coating in accordance with ASTM B 633, Electrodeposited Coatings of Zinc on Iron and Steel. Screw strength shall be calculated in accordance with AISI S100 Section J4, if applicable, or shall be based on the manufacturer’s design capacity determined from testing.
- Local and/or regional building codes may require meeting special conditions. Building codes often require special inspection of anchors installed in concrete and masonry. For compliance with these requirements, it is necessary to contact the local and/ or regional building authority. Except where mandated by code, Simpson Strong-Tie products do not require special inspection.
- Throughout the catalog there are installation drawings showing the load transfer from one element in the structure to another. Additional connections may be required to safely transfer the loads through the structure. It is the designer’s responsibility to specify and detail all necessary connections to ensure that a continuous load path is provided as required by the building code.
- Top flange hanger allowable loads are typically based on testing with solid headers. Load reductions may apply when using headers comprised of multiple plies of dimensioned lumber or SCL. See technical bulletin T‑C‑MPLYHEADR at strongtie.com for more information.
- For connections involving members with different specific gravities, use the allowable load corresponding to the lowest specific gravity in the connection, unless noted otherwise.