HDQ8/HHDQ Heavy Duty Holdown

Installation

View step-by-step installation instructions

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® screws (SDS) which install easily, reduce fastener slip and provide a greater net section area of the post when compared to bolts. They may be installed either flush or raised off the mudsill without a reduction in load value.

Special Features:

Uses SDS screws which install easily, reduce fastener slip, and provide 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: HDQ8 - 7 gauge; HHDQ - Body: 7 gauge, washer: 1/2" plate

Finish: HDQ8 - Galvanized; HHDQ - Simpson Strong-Tie® gray paint

Installation:

Use all specified fasteners. See General notes.
For use in vertical and horizontal applications.
No additional washer is required.
To tie multiple 2x members together, the Designer must determine the fasteners required to join members to act as one unit without splitting the wood. See SDS values.
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.
Refer to Anchor Designer Software™ for ACI 318 for anchoring solutions.

HDQ8:

5/8" of adjustability perpendicular to the wall.
See SSTB Anchor Bolts for anchorage options. For 2-2x and 3x sill plates use SSTBL models. The Designer may specify any alternate anchorage calculated to resist the tension load for a specific job. Anchorage length should take the bearing plate/washer height into account, to ensure adequate length of threads to engage the nut.

HHDQ11/14:

No additional washer is required.
HHDQ14 requires a heavy hex anchor nut (supplied with holdown)
See SB Anchor Bolts for anchorage options

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.

Allowable loads have been increased for wind or earthquake load durations with no further increase allowed; reduce where other load durations govern.
The Designer must specify anchor bolt type, length and embedment. See SB and SSTB Anchor Bolts. Refer to Anchor Designer Software™ for ACI 318 for anchoring solutions.
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-SCLCOLUMN for values on the narrow face (edge).
Post design by Specifier. Allowable load values are based on a minimum wood member thickness in the direction of the fastener penetration. Posts may consist of multiple 2x members provided they are designed to act as one unit independently of the holdown fasteners. Holdowns shall be installed centered along the width of the attached post.
Tension values are valid for holdowns flush or raised off of sill plate.
Deflection at Highest Allowable Tension Load includes fastener slip, holdown elongation, and anchor bolt elongation (L = 6"). Additional elongation of anchor bolts shall be accounted for by the Designer when holdowns are raised higher than 6".
Tabulated loads may be doubled when the HDQ8 is 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.
Noted HHDQ14 allowable loads are based on a 5 1/2" wide post (6x6 min.).All other loads are based on 3 1/2" wide post minimum.
Requires heavy hex anchor nut to achieve tabulated loads (supplied with holdown).
HHDQ holdowns installed horizontally can achieve compression loads with the addition of a standard nut on the underside of the load transfer plate. Refer to ESR 2330 for design values. Design of anchorage rods for the compression force shall be per the Designer.

					Legacy Reports
	IAPMO ES ER	ICC-ES ESR	CITY OF LOS ANGELES	STATE OF FLORIDA	ICC-ES NER	ICC-ES ER	ICC-ES ES
HHDQ	See specific model numbers for code listings.
HHDQ11-SDS2.5		ESR-2330 / ESR-2523 *	RR25720	FL10441
HHDQ14-SDS2.5		ESR-2330 / ESR-2523 *	RR25720	FL10441
HHDQ8-SDS3	No code listing: Please contact us for test data.

* 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

Download the Simpson AutoCad Menu, which allows you to insert Ortho views directly into your AutoCAD drawing.

	ORTHOGRAPHIC	PERSPECTIVE
HDQ8	HDQ8: DWG \| DXF HDQ8 front view: DWG \| DXF HDQ8 left view: DWG \| DXF HDQ8 right view: DWG \| DXF HDQ8 top view: DWG \| DXF	High Wind-Resistant Construction D89: Holdowns: DWG \| DXF HDQ8: DWG \| DXF
HHDQ	None for this model	None for this model
HHDQ11	HHDQ11: DWG \| DXF HHDQ11 front view: DWG \| DXF HHDQ11 left view: DWG \| DXF HHDQ11 right view: DWG \| DXF HHDQ11 top view: DWG \| DXF	None for this model
HHDQ14	HHDQ14: DWG \| DXF HHDQ14 front view: DWG \| DXF HHDQ14 left view: DWG \| DXF HHDQ14 right view: DWG \| DXF HHDQ14 top view: DWG \| DXF	None for this model