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HDU/DTT Holdowns

HDU/DTT

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 Heavy-Duty Connector 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 DTT tension ties are designed for lighter-duty holdown applications on single 2x posts. The new DTT1Z is installed with nails or Simpson Strong-Tie Strong-Drive SD Connector screws and the DTT2Z installs easily with the Strong-Drive SDS Heavy-Duty Connector screws (included). The DTT1Z holdowns have been tested for use in designed shearwalls and prescriptive braced wall panels as well as prescriptive wood-deck applications (see DTT Deck Tension Ties for deck applications).

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

Key Features

  • Holdown designs virtually eliminate deflection due to material stretch.
  • Uses Strong-Drive SDS Heavy-Duty Connector screws which install easily, reduce fastener slip, and provide a greater net section area of the post compared to bolts.
  • Strong-Drive SDS Heavy-Duty Connector 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; DTT1Z and DTT2Z – ZMAX® coating; DTT2SS – stainless steel

Installation

  • Use all specified fasteners. See Holdown and Tension Tie General Notes.
  • The HDU requires no additional washer, the DTT requires a standard cut washer (included with DTT2Z) be installed between the nut and the seat.
  • Strong-Drive SDS Heavy-Duty Connector screws install best with a low speed high torque drill with a 3/8" hex head driver.
  • For holdowns, per ASTM test standards, anchor bolt nut should be finger-tight plus 1/3 to 1/2 turn with a hand wrench, with consideration given to possible future wood shrinkage. Care should be taken to not over-torque the nut. Impact wrenches should not be used

Related Literature

Load Tables

    These products are available with additional corrosion protection. Additional products on this page may also be available with this option, check with Simpson Strong-Tie for details.

  1. See Holdown and Tension Tie General Notes.
  2. Noted HDU14 allowable loads are based on a 5 1/2" wide post (6x6 min.).
  3. HDU14 requires heavy hex anchor nut to achieve tabulated loads (supplied with holdown).
  4. Loads are applicable to installation on either narrow or wide face of post.

Code Reports

Part IAPMO UES ER ICC-ES ESR City of Los Angeles State of Florida
DTT1Z ER-102 ER-130
DTT2Z ESR-2330 ESR-2523 RR25720 FL10441
DTT2Z-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HDUSee specific model numbers for code listings.
HDU11-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HDU14-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HDU2-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HDU4-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HDU5-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HDU8-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441

ESR-2523 is an Index of many of Simpson Strong-Tie Stamped and Welded Cold-formed Steel Products for Wood or Cold-formed Steel Construction

Drawings

Part Orthographic Perspective
DTT1Z
DTT1Z bottom view
DWG DXF
DTT1Z front view
DWG DXF
DTT1Z left view
DWG DXF
DTT1Z right view
DWG DXF
DTT1Z top view
DWG DXF
DTT1Z
DWG DXF
DTT2Z
DTT2Z
DWGDXF
DTT2Z front view
DWG DXF
DTT2Z left view
DWG DXF
DTT2Z right view
DWG DXF
DTT2Z top view
DWG DXF
High Wind-Resistant Construction D61: Stemwall/Crawlspace
DWG DXF
DTT2Z
DWG DXF
DTT2Z installed
DWG DXF
HDUNone None
HDU11
HDU11
DWGDXF
HDU11 front view
DWG DXF
HDU11 right view
DWG DXF
HDU11 top view
DWG DXF
None
HDU14
HDU14
DWGDXF
HDU14 front view
DWG DXF
HDU14 left view
DWG DXF
HDU14 right view
DWG DXF
HDU14 top view
DWG DXF
None
HDU2
HDU2
DWGDXF
HDU2 front view
DWG DXF
HDU2 right view
DWG DXF
HDU2 top view
DWG DXF
High Wind-Resistant Construction D46: Stud to Band Joist
DWG DXF
High Wind-Resistant Construction D9: Girder/Truss to Wall Framing
DWG DXF
HDU4
HDU4
DWGDXF
HDU4 front view
DWG DXF
HDU4 right view
DWG DXF
High Wind-Resistant Construction D8: Girder/Truss to Wall Framing
DWG DXF
HDU5
HDU5
DWGDXF
HDU5 front view
DWG DXF
HDU5 right view
DWG DXF
High Wind-Resistant Construction D101: Holdowns
DWG DXF
High Wind-Resistant Construction D21: Girder/Truss To Masonry/Concrete
DWG DXF
High Wind-Resistant Construction D49: Floor to Masonry/Concrete
DWG DXF
HDU8
HDU8
DWGDXF
HDU8 front view
DWG DXF
HDU8 right view
DWG DXF
None