HDU Holdowns are pre-deflected during the manufacturing process, virtually eliminating deflection under load due to material stretch. They use Simpson Strong-Tie® Strong-Drive® SDS screws which install easily, reduce fastener slip and provide a greater net section when compared to bolts.

The HDU series of holdowns are designed to replace previous versions of the product such as PHD's as well as bolted holdowns. The HDU2, 4 and 5 are direct replacements for the PHD2, 5 and 6, respectively.

The DTT2Z tension tie is suitable for lighter-duty holdown applications on single or double 2x posts, and installs easily with Strong-Drive SDS screws (included). The DTT2Z has been tested in accordance with the ICC-ES acceptance criteria for Holdowns Attached to Wood Members (AC155) and meets the minimum requirements for many alternate braced wall panels per section R602.10.3.2 of the 2009 IRC (see table R602.10.6, item 1).

For more information on holdown options, contact Simpson Strong-Tie.

HDU Special Features:

• Pre-deflected body virtually eliminates deflection due to material stretch.
• Uses SDS screws which install easily, reduces fastener slip, and provides a greater net section area of the post compared to bolts.
• SDS screws are supplied with the holdowns to ensure proper fasteners are used.
• No stud bolts to countersink at openings.

Material: See table.

Finish: HDU – Galvanized; DTT2Z – ZMAX® coating; DTT2SS - stainless steel

Installation:

• Use all specified fasteners. See General Notes.
• For use in vertical and horizontal applications.
• The HDU requires no additional washer, the DTT requires a standard cut washer (included) be installed between the nut and the seat.
• To tie multiple 2x members together, the Designer must determine the fasteners required to join the members to act as one unit without splitting the wood. See SDS Screw information.
• See SB and SSTB Anchor Bolts for anchorage options.
• SDS screws install best with a low-speed, high-torque drill with a 3/8" hex head driver.

1. Allowable loads have been increased for wind or earthquake load durations with no further increase allowed; reduce where other load durations govern.
2. The Designer must specify anchor bolt type, length and embedment. See SB and SSTB Anchor Bolts.
3. Structural composite lumber columns have sides that show either the wide face or the edges of the lumber strands/veneers. Values in the tables reflect installation into the wide face. See technical bulletin T-C-SCLCLM for values on the narrow face (edge).
4. Post design by Specifier. Tabulated loads are based on a minimum 3 1/2" wide post (in a 3 1/2" wall). Post may consist of multiple members provided they are connected independently of the holdown fasteners. See Post Capacities for common post allowable loads.
5. Tension values are valid for holdowns flush or raised off of sill plate.
6. Deflection at Allowable Tension Load includes fastener slip, holdown deformation and anchor rod elongation for holdowns installed up to 6" above top of concrete. Holdowns may be installed raised up to 18" above top of concrete with no load reduction provided that additional elongation of the anchor rod is accounted for.
7. Tabulated loads may be doubled when the holdowns are installed on opposite sides of the wood member provided either the post is large enough to prevent opposing holdown screw interference or the holdowns are offset to eliminate screw interferences.
8. Noted HDU14 allowable loads are based on a 5 1/2" wide post (6x6 min.).
9. Requires heavy hex anchor nut to achieve tabulated loads (supplied with holdown).
10. Loads are applicable to installation on either narrow or wide face of post