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HDQ/HHDQ Holdowns

HDQ/HHDQ

The HHDQ series of holdowns combines low deflection and high loads with ease of installation. The unique seat design of the HDQ8 greatly minimizes deflection under load. Both styles of holdown employ the 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. They may be installed either flush or raised off the mudsill without a reduction in load value.

Key Features

  • 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

  • HDQ8 — 7 gauge; HHDQ — body: 7 gauge, washer: 1/2" plate

Finish

  • HDQ8 — galvanized; HHDQ — Simpson Strong-Tie® gray paint; HHDQ11 — available in stainless steel

Installation

  • Use all specified fasteners; see Holdown and Tension Tie General Notes
  • No additional washer is required
  • Strong-Drive SDS Heavy-Duty Connector screws install best with a low-speed high-torque drill with a 3/8" hex-head driver

HDQ8:

  • 5/8" of adjustability perpendicular to the wall

HHDQ11/14:

  • No additional washer is required
  • HHDQ14 requires a heavy-hex anchor nut (supplied with holdown)

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 HHDQ14 allowable loads are based on a 5 1/2" wide post (6x6 min.) Other loads based on 3 1/2" wide post minimum.
  3. HHDQ14 requires heavy-hex anchor nut (supplied with holdown).
  4. HDQ and HHDQ installed horizontally achieve compression loads with the addition of a standard nut on the underside of the load transfer plate. Refer to ICC-ES ESR-2320 for design values. HDQ8 requires a standard nut and BP7/8-2 (sold separately) load washer on the underside of the holdown for compression load. Design of anchorage rods for compression force shall be per the Designer.

Code Reports

Part IAPMO UES ER ICC-ES ESR City of Los Angeles State of Florida
HDQ8-SDS3 ESR-2330 ESR-2523 RR25720 FL10441
HHDQSee specific model numbers for code listings.
HHDQ11-SDS2.5 ESR-2330 ESR-2523 RR25720 FL10441
HHDQ14-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
HDQ8-SDS3
SW1 Detail Sheet
DWGDXF
SW2 Detail Sheet
DWGDXF
SWP Detail Sheet
DWGDXF
HDQ8-SDS3 Front View
DWG DXF
HDQ8-SDS3 Left View
DWG DXF
HDQ8-SDS3 Right View
DWG DXF
HDQ8-SDS3 Top View
DWG DXF
HDQ8-SDS3 Installed Perspective View
DWG DXF
HDQ8-SDS3 Installed Perspective View - Horizontal
DWG DXF
HHDQNone None
HHDQ11None None
HHDQ14None None
HHDQ8None None