HDA/HD Holdowns

HD10A
(HD6A, HD8A and HD14A similar)

HD5A
(HD2A similar)

Vertical HD5A Installation with SSTB anchor bolt.
Washers are not required at the base.

Typical HD5A Tie Between Floors
*To achieve table loads, the minimum bolt end distance is seven bolt diameters. This distance is designed into holdowns.
BP's are required by the City of Los Angeles. Check with your local building code on usage. (2005 NDS Section 11.1.2.3 requires a metal plate, metal strap, or minimum of a standard cut washer.)

HD2A installed as a lateral anchor for a deck guardrail post. Refer to technical bulletin T-HD2AGRDRL for more information.

Vertical HD15 Installation

All HDAs and the HD15 are self-jigging, ensuring code-required minimum 7 bolt diameter spacing from the end of the wood member to the center of the first bolt hole per NDS-2005 Section 11.5.1.

HD6A, HD8A, HD10A and HD14A's seat design allows greater installation adjustability. An overall width of 3 1/4" for the HD6A, HD8A and HD10A, and 3 1/2" for the HD14A provides an easy fit in a standard 2x4 stud wall.

HDA/HD Special Features:

Load Transfer Plate eliminates the need for a seat washer.
Fewer inspection problems.

Material: See table.

Finish: HD14A and HD15 - Simpson gray paint. Other HDA's - galvanized. May be ordered HDG; contact Simpson.

Installation:

Use all specified fasteners. See General Notes.
Contact engineered wood manufacturers for connections that are not through the wide face.
For an improved connection, use a steel nylon locking nut or a thread adhesive on the anchor bolt.
Bolt holes shall be a minimum of 1/32" to a maximum of 1/16" larger than the bolt diameter (per NDS, section 11.1.2).
With the exception of the HD15, a washer is not required between the base plate of the holdown and the anchor nut. Use a standard washer on the HD15 anchor.
SSTB Anchor Bolts, Simpson's Anchoring Systems and Additional Anchorage Designs for anchorage options. The Designer may specify any alternate anchorage calculated to resist the tension load for a specific job.
Locate on wood member to maintain a minimum distance of seven bolt diameters, distance is automatically maintained when end of wood member is flush with the bottom of the holdown.
Stud bolts should be snugly tightened.
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.)
See 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.

roll over images below to see larger image

HD, HDA, HD2A, HD5A, HD6A, HD8A, HD10A, HD14A, HD15

Allowable loads have been increased for earthquake or wind load duration wth no further increase allowed; reduce where other load durations govern.
HD15 requires a minimum 4x8 (in a 3 1/2" wide shearwall) or a 6x6 nominal post. To ensure the tension load carrying capacity of the critical net section meets the holdown capacity.
Use a minimum 4x6 nominal post for the HD14A. Minimum post size is required to ensure the tension load carrying capacity of the critical net section meets the holdown capacity.
HB is the required minimum distance from the end of the stud to the center of the first stud bolt hole. End distance may be increased as necessary for installation.
The designer must specify anchor bolt type, length and embedment. See SSTB Anchor Bolts and Additional Anchor Designs.
Refer to technical bulletin T-ANCHORSPEC for retrofit anchorage solutions.
Lag bolts will not develop the listed loads.
See Product Use Information.
Deflection at Highest Allowable Tension Load includes holdown elongation and anchor bolt elongation (L = 5"). Additional elongation of anchor bolts longer than 5" shall be added to holdown deflection.
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.
To achieve published loads, machine bolts shall be installed with the nut on the opposite side of the holdown (see picture). If reversed, the Designer shall reduce the allowable loads shown per NDS requirements when bolt threads are in the shear plane.
HDA and HD allowable loads are based on the lower of the 2005 NDS fastener values or the ultimate load on a steel test jig divided by 2.5.
Post design shall be by Designer.
Holdowns may be raised off sill plate. Refer to table for increased deflection values (if applicable). Refer to note q, General Instructions for the Installer for installation instructions of raised holdowns.

					Legacy Reports
	IAPMO ES ER	ICC-ES ESR	CITY OF LOS ANGELES	STATE OF FLORIDA	ICC-ES NER	ICC-ES ER	ICC-ES ES
HD	See specific model numbers for code listings.
HD10A			RR25528	FL503		ER-5708
HD14A			RR25528	FL503		ER-5708
HD15			RR25528	FL503		ER-5708
HD2A			RR25528	FL503		ER-5708
HD5A			RR25528	FL503		ER-5708
HD6A			RR25528	FL503		ER-5708
HD8A			RR25528	FL503		ER-5708
HDA	See specific model numbers for code listings.