Wood Construction Connectors - Page 16

®	PHD PREDEFLECTED  HOLDOWNS

The Predeflected Holdown (PHD) is a revolutionary development in holdown connections. This connector is predeflected during manufacturing, to virtually eliminate deflection from material stretch.

SPECIAL FEATURES:

• Wood screws reduce slip due to overdrilled bolt holes.
• The slot in the seat provides anchor bolt adjustment.
• Smaller centerline reduces eccentricity in the stud.
• No stud bolts to countersink.
• Fits easily on a 4x stud.

MATERIAL: See table

FINISH: Galvanized

INSTALLATION:

• Use all specified fasteners. See General Notes.
• Place the PHD over the anchor bolt.
• Install Simpson's code-recognized SDS1/4X3 wood screws, which are provided with the holdown.
• For an improved connection, use a steel nylon locking nut or a thread adhesive on the anchor bolt.
• See SSTB Anchor Bolts for anchorage options. The design engineer may specify any alternate anchorage calculated to resist the tension load for a specific job. Anchorage length should take the bearing plate height of 1-5/8" into account, to ensure adequate length of threads to engage the nut.

• To tie double 2x members together, the designer must determine the fasteners required to bind members to act as one unit without splitting the wood.

CODES- City of L.A. RR25300; ICBO 5328.

1. Allowable loads have been increased 33% for earthquake or wind loading with no further increase allowed; reduce where other loads govern.
2. The anchor embedment and configuration must be specified. See the SSTB Anchor Bolts.
3. See pg 24 for anchor bolt retrofit.
4. Loads are based on static tests on wood studs, limited by the lowest of 0.125" deflection, ultimate divided by 3, or the wood screw value.
5. Deflection at Highest Allowable Design Load: The deflection of a holdown measured between the anchor bolt and the strap portion of the holdown when loaded to the highest allowable load listed in the catalog table. This movement is strictly due to the holdown deformation under a static load test conducted on a steel jig.
6. Installs best with a low speed 1/2" right angle drill with a 3/8" hex head driver.
7. PHD installed raised off the sill plate may have greater deflection values.

SCREWS

The Simpson Strong-Drive^® wood screw has a hex washer head for easy driving with a socket wrench. The built-in reamer and type 17 tip cuts a hole to allow installation without predrilling. Predrilling may be necessary depending on the type and moisture content of wood.

The Strong-Drive SD8X1.25 screw has a needle point for fast starts; a double thread shank that reduces installation time and cost; a #2 deep Phillips drive to reduce stripping, and a wafer head with low profile finish.

CODES: ICBO No 5268; City of LA. RR 25281.

TO ORDER DISPLAY PACKS:

SD8X1.25MSTRCTN --  24 packs of 100 screws.

SDS1/4X3 MSTR CTN --  12 packs of 50 screws. 35lb Bulk Boxes -- available for 950 SDS1/4X3 screws.

Model No.	Description	Metric Equivalent (mm)	Finish3	Fasteners per carton	Doug Fir-Larch/So. Pine Allowable Loads1			Spruce-Pine-Fir Allowable Loads1
					Light Gauge		3 Gauge	Light Gauge		3 Gauge
					Shear (100)	Gauge	Shear (100)	Shear (100)	Gauge	Shear (100)
SDS1/4x1-1/2	1/4" x 1-1/2" Wood screw	6.1 x 38	ZINC	1500	268	10	290	231	10	251
SDS1/4x1-3/4	1/4" x 1-3/4" Wood screw	6.1 x 44.5	ZINC	1400	303	10	327	261	10	284
SDS1/4x2	1/4" x 2" Wood screw	6.1 x 50.8	ZINC	1300	303	10	327	261	10	284
SDS1/4x2-1/2	1/4" x2-1/2" Wood screw	6.1 x 63.5	ZINC	1100	303	10	327	261	10	284
SDS1/4X3	1/4" x 3" Wood screw	6.1 x 76.2	ZINC	950	303	10	327	261	10	284
SDS 1/4X6	14" x 6" Wood screw	6.1 x 152.4	ZINC	600	303	10	327	261	10	284
SD8X1.25	#8 x 1-1/4" Tapping Screw	4.1 x 31.7	EG	--	76	18	--	65	18	--

1. Allowable loads are based on the 1997 NDS, Adjustments are made for use with metal side plates, Fes = 45 ksi. Loads under light gauge are for gauges listed through 22 gauge. Allowable loads for gauges not indicated must be calculated according to the code. Contact factory for more details.
2. Metric equivalents are listed by Diameter x Length.
3. Zinc = Yellow zinc dichromate.
4. Installs best with a low speed 1/2" right angle drill with a 3/8"" hex head driver.
5. For wood-to-wood applications, call Simpson for load values and minimum required penetration.
6. SDS1/4X3 are required for PHD's. Call Simpson for PHD values using SDS1/4X1-1/2" screws for 2x application.