Simpson Strong-Tie reserves the right to change specifications, designs, and models without notice or liability for such changes.
Steel used for each Simpson Strong-Tie® product is individually selected based on the product’s steel specifications, including strength, thickness, formability, finish and ability to weld. Contact Simpson Strong-Tie for steel information on specific products.
Unless otherwise noted, dimensions are in inches, loads are in pounds.
All installations should be designed in accordance with the published allowable load values. The designer is responsible for verifying that all design loads do not exceed the allowable loads listed for each component in the restraint system. Do not exceed published allowable loads that would jeopardize the connectors.
Wood shrinks and expands as it loses and gains moisture content, particularly perpendicular to its grain. Take wood shrinkage into account when designing and installing connections. The effects of wood shrinkage are increased in multiple lumber connections, such as floor-to-floor installations. This may result in the nuts for the vertical rod system becoming loose, requiring tightening (unless shrinkage compensating devices are installed). Section 2304.3.3 of the 2018 IBC requires wood structures supporting more than two floors and a roof be analyzed for the effects of wood shrinkage. Refer to the wood shrinkage web application on strongtie.com/software for more information. See ICC-ES ESR-2320 for additional information on Simpson Strong-Tie take-up devices.
Simpson Strong-Tie recommends notifying the designer or stating the project lumber moisture content on the construction documents if the anticipated moisture content exceeds or falls below general industry standards. Simpson Strong-Tie assumes structural dry lumber and considers a range of a 10% change from Initial moisture content to equilibrium moisture content when calculating the estimated building shrinkage as used for determining the rated deformation compensation capacity for take-up devices (ATUD/TUD).
The term “designer” used throughout this guide is intended to mean a qualified licensed professional engineer or a qualified licensed architect.
All connected members and related elements shall be designed by the designer. Where multiple members of lumber are intended to act as one unit, they must be fastened together to resist the applied load. This design must be determined by the designer.
Local and/or regional building codes may require meeting special conditions, such as rod elongation limits. Also, 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.
Components should be kept dry and away from corrosive materials and away from steel that has already shown signs of corrosion.
Once installed, take precautions to prevent the RTUD from getting wet and freezing. Permanent damage may result if the installed device freezes when it has water inside it.
When fire caulking or spray-on insulation is required, the specified material shall not be corrosive to metal when used in contact with the ATS system. Shrinkage compensating devices (e.g., RTUD, ATUD, TUD) have moving components and may not function properly with debris interference, direct contact with fire caulking or spray insulation shall be avoided. Indirect contact shall also be avoided, as remnants of the caulking material may still be held in the rod threads, which can be detrimental to the performance of the components when the rod passes through the device during building shrinkage. The fire caulking or spray insulation material material should also be pliable in order to be compatible with wood shrinkage and general light frame construction residual movement.