HDU Holdown

The HDU series of holdowns are the latest in a long series of innovations from Simpson. These holdowns combine the advantages of low deflection and high capacity from the pre-deflected geometry with the ease of installation of Simpson's patented SDS screws.

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 1/4"x2 1/2" screws are supplied with the holdowns. (Lag screws will not achieve the same load.) This ensures the proper fasteners are used and is convenient for the installer.
No stud bolts to countersink at openings.

Material: See table.

Finish: Galvanized.

Installation:

Use all specified fasteners. See General Notes.
Place the HDU over the anchor bolt.
No additional washer required.
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.
Refer to technical bulletin T-ANCHORSPEC for post-installed anchorage solutions.

For holdowns, per ASTM test standards, anchor bolt nuts 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 and SSTB Anchor Bolts.
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 and raised off of sill plate.
Deflection at Highest Allowable Tension Load includes fastener slip, holdown elongation, and anchor bolt elongation (L = 5"). Additional elongation of anchor bolts longer than 5" shall be added to holdown deflection.
Tabulated loads may be doubled when the HDU 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 HDU14 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.
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
HDU	See specific model numbers for code listings.
HDU11	No code listing. Please contact us for test data.
HDU11-SDS2.5		ESR-2330	RR25720	FL6482
HDU14-SDS2.5		ESR-2330		FL10246
HDU2	No code listing. Please contact us for test data.
HDU2-SDS2.5		ESR-2330	RR25720	FL6482
HDU4	No code listing. Please contact us for test data.
HDU4-SDS2.5		ESR-2330	RR25720	FL6482
HDU5	No code listing. Please contact us for test data.
HDU5-SDS2.5		ESR-2330	RR25720	FL6482
HDU8	No code listing. Please contact us for test data.
HDU8-SDS2.5		ESR-2330	RR25720	FL6482