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UL L521

Wood Truss

Fire Rating 1 hours
System STC 59
System IIC 51
System Thickness 20 3/4 in.

CAD/Revit & Acoustics

Assembly Construction

Assembly Construction

Layer 1 - Finish Flooring:

Ceramic Tile (By Others)

Layer 2 - Subfloor Topping Mixture:

1" Thick Levelrock® Brand 2500 Series Floor Underlayment

Layer 3 - Sound Mat:

1/4" Thick Levelrock® Brand SAM-N25™ Sound Attenuation Mat

Layer 4 - Subflooring:

23/32" Plywood Panel

Layer 5 - Trusses:

18" Parallel Chord Open Web Trusses, Spaced 24" O.C.

Layer 6 - Insulation:

3-1/2" Unfaced Glass Fiber

Layer 7 - Resilient Channel:

25 ga. Resilient Channels Spaced 16" O.C. (Sound Tested with RC Deluxe®)

Layer 8 - 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.