HHDQ Heavy Duty Holdown

The HHDQ series of holdowns combine low deflection and high loads with ease of installation by using Simpson’s patented SDS screws. They may be installed either flush or raised off the mudsill without a reduction in load value.

Finish: Gray paint.

Installation:

Use all specified fasteners. See General notes.
1 1/2" centerline dimension for reduced eccentricity.
Use in vertical or horizontal applications.
Install Simpson SDS 1/4"x2 1/2" wood screws, which are supplied. (Lag screws will not achieve the same load.)
The load transfer plate is an integral part of the HHDQ; no additional washer is required.
SDS screws install best with a low speed high torque drill with a 3/8" hex head driver.
Refer to technical bulletin T-ANCHORSPEC for post-installed anchorage solutions.
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 Screw information.

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 earthquake or wind 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 Anchor Bolt.
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.
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 with and raised above the sill.
Deflection at Highest Allowable Tension Load includes fastener slip, holdown elongation, and anchor bolt elongation (L = 5").
Tabulated loads may be doubled when the HHDQ is installed on opposite sides of the wood member provided either the post is large enough to prevent opposing holdown screw inferference 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.
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.
Allowable loads are based on criteria in ICC-ES AC155. Therefore, they are the lower of the strength determined from the test value on a wood jig divided by 3.0, the load at the AC155 deflection limit, and the fastener calculation based on the 2005 NDS.

					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		ESR-2330	RR25720
HHDQ11-SDS2.5		ESR-2330	RR25720	FL6482
HHDQ14		ESR-2330	RR25720
HHDQ14-SDS2.5		ESR-2330	RR25720	FL6482