| 1. | Topping is optional can be lightweight or proprietary topping. |
| 2. | Sub-Flooring: 5/8 tongue & groove plywood or OSB or Equivalent. |
| 3. | Structural Members: Open Joist 2000, 9 3/8" depth minimum & 16" maximum, installed up to 24" o.c., with structural graded 2 x 3 or 2 x 4 chords per NLGA grading rules. Structural member should bear the Warnock Hersey certification mark. |
| 4. | Bridging: Continuous 2 x 4 Lumber nailed to the bottom chord and the sides of the diagonals with 2" long nails. |
| 5. | Resilient Channel: Galvanized Steel 24 gauge spaced 16" o.c. & attached to the bottom chord by means of 2 Type W screws. Channels overlap 10" at the end & are attached to each other by 1-1/4" Type S screws. |
| 6. | Gypsum Board: 2 layers 1/2" thick Type X. Long edges located between joists perpendicular to the resilient channels. Short edges are staggered by 4'. Sheets are fastened to the resilient channels by means of 1-1/2" Type S screw located 1-1/2" away from the edge & 3" from the long edges. Screws are spaced 6" o.c. Joints are taped & finished with 2 layers of compound. |
| 7. | Insulation material is optional for acoustic and/or thermal protection. |
| 1. | Topping: Topping is optional can be lightweight or proprietary topping. |
| 2. | Sub-Flooring: 5/8" Tongue & groove plywood or OSB or equivalent. |
| 3. | Structural Members: Open Joist 2000®, minimum depth 9-3/8", installed up to 24" oc, with structural grade 3x2 or 4x2 chords per NLGA grading rules for Canadian Lumber or graded by an inspection bureau or agency approved by the United States Department of Commerce Board of Review of the American Lumber Standards Committee with chord sizes of 3x2, 4x2. Open Joist 2000® should bear the WHI Certification Mark. |
| 4. | Bridging: Continuous 2x4 lumber nailed to the bottom chord and the sides of the diagonals with 2" long nails. |
| The Ceiling Membrane shall consist of three layers of 5/8" (15.9mm) proprietary Type C Gypsum board. Each sheet will be not less than 4' (1.22m) wide. Acceptable products include, but are not limited to: Lafarge North America Firecheck C gypsum board; National Gypsum Gold Bond Firesheild C gypsum board; and Georgia Pacific (GP) Gypsum ToughRock Fire Guard C gypsum. board. |
| 5. | Resilient Channel: Rigid steel furring channels (inverted hat-type) approximately 3/4" (19mm) deep, spaced not more than 16" (406mm) oc. These channels shall be oriented perpendicular to the joists and attached to each truss using 1-1/2" (70mm) Type S or W screws. If Open Joist 2000® members are installed at 16" oc or less, this resilient channel is optional. |
| 6. | Gypsum Board:
Base Layer of Gypsum Board: The base or uppermost layer of gypsum board shall be attached directly to the channels (or bottom chord). The long-edges of the gypsum board shall be oriented perpendicular to the trusses and with all end joints centered over the trusses. End joints must be staggered by at least two supports. The panels of gypsum board in the base layer shall be attached directory to the bottom of the trusses using Type S or Type W wallboard screws not less than 2" (50mm) in length. The screws shall be spaced not more than 7" (175mm) apart along each truss. Screws shall be kept at least 1-1/2" (38mm) from the sides and 1" (25mm) from the ends of each sheet.
Second layer of Gypsum Board: All joints between sheets in the second or middle layer of gypsum board must be staggered from those in the base layer. Except for the ends of each sheet, the second layer of gypsum board shall be attached to trusses using Type S or Type W wallboard screws not less than 2-1/2" (64mm) in length. The screws shall be spaced not more than 7" (175mm) apart along each truss. Screws shall be kept at least 1-1/2" (38mm) from the sides of each sheet. The ends of each sheet in the second layer of gypsum board shall be attached to the gypsum board in the uppermost layer using Type G wallboard screws not less than 1-1/2" (38mm) long. These screws shall be spaced not more than 7" (175mm) apart and will be kept at least 1-1/2" )38mm) from the ends of each sheet.
Resilient Channel: Rigid steel furring channels (inverted hat-type) approximately 3/4" (19mm) deep spaced not more than 16" (406mm) oc shall be installed beneath the second layer of gypsum board. These channels shall be oriented perpendicular to the joists and attached to each truss using 2-3/4" (70mm) Type S screws.
Face Layer of Gypsum Board: The face or lowermost layer of gypsum board shall be attached directly to the rigid steel furring channels. The long-edges of the gypsum board shall be oriented perpendicular to the furring channels and with all end joints centered over the channels. End joints must be staggered at least two supports. The panels of gypsum board in the face layer shall be attached to the furring channels using Type S wallboard screws not less than 1-1/4" (32mm) in length. The screws shall be spaced not more than 7" (175mm) apart along each channel. Screws shall be kept at least 1-1/2" (38mm) from the sides and 1/2" (12mm) from the ends of each sheet
All Joints between adjacent sheets of gypsum board in the face layer shall be taped and finished and the heads of all screws used to attach that layer of gypsum board to the furring channels shall be treated (finished), as specified in ASTM-C840 (Standard Specification for Application and Finishing of Gypsum Board) and CAN/CSA-A82.31 (Gypsum Board Application. |
| 7. | Insulation: Insulation material is optional. |