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<br />Page 2 of 4 Report No. NER•392
<br />4.2.1.2 Wood Trusses: Trusses shall be spaced a mazi-
<br />mum of 24 inches (61D mm) on cenler and shall have n
<br />minimum truss depth of 16 inches (406 mm).
<br />4.2.1.3 Bradng: Bracing shall be minimum 2�6 nominal
<br />Imnber, orienled verlically and installed porpendicular to
<br />trusses on maximum 10-foot (3048 mm) centers. Bracing
<br />shall be secured to each tmss wilh three t6d nails.
<br />4.2.1.4 Wallboard Edge Blocking: Adjacent ceiling wall-
<br />board edges perpendicular to trusses shall have FR-Quik
<br />Channel Sels centered longlhwise over Ihe wallboard joints.
<br />The channeis shall be secured lo the lrusses with one
<br />t-inch-long Type S drywall screw at each end.
<br />4.2.1.5 Gypsum Waliboard: Gypsum wallboard shall be
<br />altached to the bottom chorcJs of the Irusses with Iho long
<br />dimension perpendicular to Irusses. The wallboards
<br />approved for use are :✓s•inch•thick (15.9 mm) Cebtex
<br />Fi•Rok Plus, Georgia Pacific Fire Slop C, Gold Bond
<br />Fire-Shield G, and US Gypsum Firecode C, Type X
<br />gypsum wall6oards. Wallboard end joinls shall 6e stag-
<br />gered a minimum of 24 inches (610 mm). 7he wallboard
<br />shall be fastened directly to Ihe Irusses with 1:�e-inch-long
<br />(41.3 mm), Type S drywall scmws on 8-inch (203 mm)
<br />cenlers, and shall be faslened lo the FR•Quik channels wilh
<br />Bond Washers (Figure 4b) and t-inch-long (25.4 mm), Type
<br />S screws spaced 8 inches (203 mm) on cenler, driven
<br />through the crease between adjacenl wallboards.
<br />4.2.1.6 Flnish System: AI� joints shall be covered with
<br />paper lape embedded in cementitous compound, and
<br />exposed screw heads shall be covered wilh compound. As
<br />an allerna�ive, nominal aiaz-inch-lhick (2.38 mm) veneer
<br />p�asler, complying with ASTM C37, is permitteA to be
<br />applied to the enlire surface of the waltboard.
<br />4.2.2 Two-hourFire-resistance•ratedFloor•ceilingand
<br />Roof•celling Assembly. FR-SYSTEM 2TM
<br />4.2.2.1 Subfloorand Roof Sheathing: Sheathing shall be
<br />minimum z3nz inch (18.3 mm) Ihick with tongue-and-groove
<br />long edges. Long edges shall be installed perpendicular to
<br />trusses. Conslruction adhesive, complying with theAFG-01
<br />conslruction-adhesive slandard, shall be applied as
<br />3ie-inch-diameter (9.5 mm) bead lo lhe lop chord o( the
<br />trusses and the grooved edges of the panels. The shealh-
<br />ing is fastened lo the tmss chords wilh 6d deformed shank
<br />nails or 8d common nails, spaced 6 inches (152 mm) on
<br />cen�er at pnnel ends and 10 inches (254 mm) on cenler in
<br />lhe lield. Undedayment shealhing shall 6e minimum va inch
<br />ihick (6.4 mm), and shall be installed with edges and ends
<br />slaggered frem the base layer sheathing in accordance with
<br />ihe applicable code.
<br />In lieu ot underinymenl, minimum ya-inch-Ihick (19.1 mm)
<br />lighiweight concrele or topping mixture is pertnitted to be
<br />substituted, in which case the base layer shealhing is
<br />permilted to be minimum �saz inch (15.1 mm) Inick, if
<br />albwed 6y the finish floor manufacWrer's speciGcations.
<br />4.2.2.2 Wood Trusses: Trusses shall be spaced a maxi-
<br />mum of 24 inches (610 mm) on center and sliall have a
<br />minimum depih, including shield member, of 16 inches (406
<br />mm). For horizontal onenlalion (Figure 2a) or vertical
<br />orienta�ion, design depih of Wsses shall be 1 vz inches (38
<br />mm) less Ihan overat depth ol wsses, including shield
<br />mem6er. A nominal2-inch-Ihick (51 mm) cnntinuous wood
<br />member, lha same widlh as lhe truss, shall be attached lo
<br />the lruss assembly adjacent to, and under, ihe boUom
<br />chord by exlending the truss plates a minimum of 1 inch
<br />(25.4 mm) onto the face of the wood member. The wood
<br />membor acls as a shield, and is permilted lo consisl of
<br />several pieces.
<br />4.2.2.3 Bracing: Oracing shali be minimum 2x6 nominal
<br />lumber orienled vertically and installed perpendicular to
<br />Irusses on maximum 10•foot (3048 mm) centers. Bracinp
<br />shal� be altached to each truss wilh three t6d nalls.
<br />4.2.2.4 Insulation: Insulalion, when used, shall be batls or
<br />rolls installed wfth stay wires located behveen Ihe trusses
<br />and wilh the ends of lhe insulalion Iocaled a minimum of
<br />1 trz inches (38 mm) above Ihe boltom face of the trusses,
<br />and lhe Ienglh of �he insulalion arched to a minimum 3
<br />inchas (76 mm) above Ihe top of the wallboard.
<br />4.2.2.5 Wallboard Edge Bloeking: Adjacent base leyer
<br />ceiling wallboard edges perpendicular to trusses shall have
<br />FR•Quik Channel Sets centered Ienglhwise over lhe
<br />wallboard joinLs. Blocking shall be secured lo irusses wilh
<br />one 1-inch-long (25.4 mm), Type S drywall screw at each
<br />end.
<br />4.2.^<.6 Gypsum Wallboard: Two layers of 5/B•inch-�hick
<br />(15.9 mm) Ceblex Fi•Rok Plus, Georgia PacHic Fire Stop C,
<br />Gold 8ond Fire•Shield G, or US Gypsum Firecode C, Type
<br />X gypsum wallboard shall be installed with bng dimensions
<br />perpendicular to Irusses and staggered between base layer
<br />and 5nish layer. Endjoints shall he on Ihe centerline of Wss
<br />chords, and a�l joinls shall ba staggered 6elween Ihe base
<br />layer and finish layer minimum 24 inches (610 mm). The
<br />base layer shall be fastened directly lo tho botlom chord of
<br />tho truss wilh minimum 2sm•inch-long (67 mm), Type S
<br />drywall screws with Bond Washers at 12 inches (305 mm)
<br />on centec The base layer is fastened to channel sets wilh
<br />'fype S, 1-inch-long (25.4 mm) screws with Bond Washers
<br />on 8-inch (203 rnm) cenlers driven Ihrough ihe crease
<br />between adjacenl wallboards. The finish I�yer shall be
<br />fastened to trusses with 2 va•inch-long (57 mm), Type X
<br />drywall screws on 8-inch (203 mm) cenlers, and wilh
<br />1 iw-inch (31.7 mm) Type G screws 12 inches (305 mm)
<br />back lrom end joints at 12 inches (305 mm) on center.
<br />An alternative installalion using resilient channels consisis
<br />of two layers of va-inch•thick (15.9 mm) Celotex Fi-Rok
<br />Plus, Georgia Padfic Fire Stop C, Gold Bond Fire-Shield G.
<br />or US Gypsum Firecoda C. Type X gypsum wallboard. The
<br />base layer shall bo inslalled with the long dimension
<br />perpendicular !o trusses. End joints shall ocwr on cenler-
<br />line of truss chords and shall be slaggered. l'he base layer
<br />shall be atlached directly lo lrusses with minimum
<br />2 s�a•inch•Iong (67 mm), Type S drywall screws spaced 12
<br />inches (305 mm) on cenler. The base layer is attached lo
<br />FR-Quik Channel sets with Bond Washers and Type S,
<br />1-inch-long (25.4 mm) screws on 8-inch (203 mm) centers,
<br />driven through lhe crease between adjacent wal�board
<br />panels. Resiiient channels formed (rom No. 25 (0.021 inch
<br />(0.53 mm)] MSG galvanized sleel, spaced 24 inches (610
<br />mm) on center, installed perpendicular to inisses and
<br />overlapped 1 uz inches (3B mm) al splices, are fastened to
<br />each truss wilh an Bd naii or a Type S, 1 ye•inch•bng (41.3
<br />mm) screw. Minirnum clearance of channels to walls shall
<br />be 3w inch (19,1 mm). Addilional pieces 60 inches (15.'4
<br />mm) long shall he placed immediately adjacent to end ianls
<br />of finish layer wallboard and shail extend 6 inches (152
<br />mm) beyond each edge of the wallboard. Finish layer
<br />wallGoard long dimensions shall be perpendicular lo
<br />channels. End joinls shall be staggered. The finish layer is
<br />fastened direcUy to the channels with Type S, t•inch-bng
<br />(25.4 mm) screws on 8-inch (203 mm) centers.
<br />4.2.2.7 Ffnish System: All joinls shail be covered with
<br />paper tape embedded in cementitous c.ompound, and
<br />exposed screw heads shall be covered with compound. As
<br />an alternative, nominal yaz-inch•thick (2.38 mm) veneer
<br />plaster, complying wilh ASTM C37. is permilled to Ge
<br />applied to the entire suriace of the wallboard.
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