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UL H505

Steel C-Joist (Load-Bearing)

Fire Rating 2 hours
System STC n/a
System IIC n/a
System Thickness 14 7/8 in.

CAD/Revit & Acoustics

Assembly Construction

Assembly Construction

Layer 1 - Structural Cement-Fiber Units:

3/4" Thick USG Structural Panel Concrete Subfloor (UL Type USGSP), With Long Dimension of Panels Perpendicular to Joists

Layer 2 - Steel Joists:

8" Min. Deep, 16 ga., Spaced 24" Max. O.C.

Layer 3 - Clip Angles (Not Shown):

One Clip Angle per Joist End

Layer 4 - Joist Bridging (Not Shown):

Cut and Bent Rim Track Screw Attached at Each End to Joists, With 1-1/2" X 20 ga. Galvanized Steel Flat Strap Bracing Attached to Bottom of Joist Flange

Layer 5 - Air Space:

4" Min. Between Bottom Flange of Joist and Main Runners

Layer 6 - Insulation:

3-1/2" Thick Glass Fiber Batt Insulation

Layer 7 - Steel Framing Members:

Suspension System May be Used in Lieu of the Resilient Channels. Main Runners, Cross Tees, Cross Channels and Wall Angle as Listed Below (UL Type DGL):

Layer 8 - Main Runners:

4' O.C. Main Runners Suspended by 12 ga. Min. Hanger Wire, 16" O.C.

Layer 9 - Cross Tees:

16" O.C.

Layer 10 - Cross Channels:

16" O.C.

Layer 11 - Wall Angle or Channel:

Painted or Galvanized Steel Angle to Support Steel Framing Member Ends and for Screw-Attachment of the Gypsum Panel (UL Type DGL)

Layer 12 - Gypsum Board:

5/8" Thick Gypsum Board (UL Type ULIX™)


  • For the most up-to-date fire-resistance ratings, refer to the UL Online Certifications Directory.
  • Estimated range of acoustical performance is based on laboratory test data of similarly constructed assemblies.