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Multi-Ply Wood Trusses Applications: Strong-Drive®
Screws (SDS) For Two-Ply 4X2 Parallel Chord Trusses

The use of Simpson Strong-Tie® Strong-Drive® screws (SDS) ensures that loads are adequately supported by both trusses. (Testing has shown that most currently available light gauge steel connectors do not uniformly distribute applied loads to both trusses.) In addition differential deflection between the two trusses is reduced.

Also see SDW Strong-Drive® Structural Wood Screws with low-profile heads for another easy-to-use, cost-effective solution for joining plated trusses

  1. Screw spacing shall not exceed 24" o.c. and shall not be less than 4" o.c. A minimum end distance of 3" shall be provided at all truss members.
  2. Gap between the trusses shall not exceed 1/8".
  3. Floor sheathing shall be screwed (or nailed) to each truss top chord. (Fastener spacing per the applicable Code requirements, or 12" o.c. max.)
  4. Strong-Drive screws are permitted to be installed through metal truss plates as approved by the Truss Designer, provided the requirements of ANSI/TPI 1-2007 Section and 8.9.2 are met (pre-drilling required through the plate using a maximum of 5/32" bit).
  5. The Truss Designer shall ensure that each truss is designed for the appropriate load(s) considering the location of the applied load(s) and the location of the Strong-Drive Screws.
  6. The Truss Designer shall design all trusses and the truss system to meet all Code and ANSI-TPI requirements.
  7. Individual screw locations may be adjusted up to 3" to avoid conflicts with other hardware or to avoid lumber defects.
  8. Strong-Drive Screws shall not be installed in areas where lumber wane exceeds 1/4".
  9. All concentrated loads were assumed to be applied at truss panel points.
  10. Installation in truss bottom chords is not recommended but is acceptable if approved by the Truss Designer.

For other multi-ply applications, see SDS for Girder Trusses and SDW Strong-Drive® Structural Wood Screws.

top Gallery:
  roll over images below to see larger image
Installation Method 1 -
Top Chord
Other web
may be used -
see footnote 5.
Installation Method 2 -
Vertical Web
Other web
may be used -
see footnote 5.
Screw position in the truss  

top Load Table:
  1. Allowable loads are based on a CD = 1.00. Increases are allowed for other durations per code to a maximum CD = 1.60.
  2. Method 1 - To be considered effective all Strong-Drive screws shall be installed within 12" of the applied concentrated load.
  3. Method 1 and Method 2 screws can be combined as required to transfer half of the applied load to the supporting truss.
  4. For uniform top chord loads, space Strong-Drive screws as required to transfer half of the applied load to the supporting truss.
  5. Web configurations other than those shown above may be used as allowed by the Truss Designer.
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