Sheathing A Roof & Sheathing A Wall on Exterior and Interior

• This is about sheathing a roof and a wall of a home, that being the first structure and most often the only structure covering either roof frame or wall frame for Before The Architect (BTA) home design  

Comment:  For more on roof framing, please see hereunder "Home Roof Construction - Roof Framing Details" at   http://searchwarp.com/swa324536.htm 

• This is not about foam board  

PERSPECTIVE

• Sheathing is the last major player in securing a home's structural durability

• Exterior load path from roof sheathing on down
  • Roof sheathing to rafters or top chords
  • Rafters or top chords to wall frame plates and walls, the latter over sheathing (to mitigate against top plates' rolling inwardly)
  • Walls to sills (below sheathing's ok)
  • Studs to studs (below sheathing's ok)
  • Wall sheathing to wall frame, continuously covering wall frame-top plates and wall frame-sill plate
  • Sill plates or mud sills to foundation  

Comment:  For more on house framing, please see hereunder "Home Building – House Frame Work, Part 1" and "Part 2" at http://searchwarp.com/swa222918.htm and http://searchwarp.com/swa223295.htm, respectively

Comment:  For more on plates to foundation, please see hereunder "Home Foundation Design - Anchor Bolt Installation" at http://searchwarp.com/swa313180.htm

• Foundation to earth  

Comment:  For more on foundations, please see hereunder "House Foundation Design Detail - Slab-On-Grade Design Basics, Scored Concrete Supplement" at http://searchwarp.com/swa210956.htm; "Home Foundation Design Details – Concrete Design" at http://searchwarp.com/swa218491.htm; "Home Foundation Design - Foundation Plan, Slab-On-Grade and T-Wall" at http://searchwarp.com/swa313149.htm; and several others by the author

Comment:  Please note that wall amendments – windows and doors – take up their own connections directly to their structure per se and directly to surrounding structure of framing and sills.

ROOF SHEATHING TO FRAME

• Roof sheathing
  • Shall be not less than 3/4 linear inch CDX plywood or equivalent
  • Oriented
    • Either with face grain perpendicular to rafters or top chords
    • Or with face grain parallel to rafters or top chords
  • Whichever way oriented, seams, or joints, between members shall be blocked solidly with sleepers not less than 2x4 nominal
  • Arranged so that butts equally share a rafter's  or top chord's nailing surface
  • Shall be applied with sheathing clips (a/k/a panel edge clips, H-clips) at midspans of rafter or top chord spacing to reinforce and space
  • Shall have adjoining, narrow-end butts aligned not more closely than 2 joists between
  • Shall continue in a whole section from a barge rafter to not less than the second common rafter in the field (to fortify the barge rafter)
  • Shall be applied with not less than 10d fully round head nails
• Plywood applied as roof sheathing shall be classified
  • Exterior Exposure
    • Not Exposure 1 and
    • Not Exposure 2
  • Structural 1  

• Nails and construction adhesive (except in Seismic Zone 2B and up whereat construction adhesive shall not be applied)
  • Shall be applied together to fasten roof sheathing and rafters or top chords
  • Adhesive
    • Shall be open on contact (taking greater care in warmer weather applications)
    • Shall be evenly distributed
    • Shall be in not less than
      • Two beads per member
      • Each bead ½ linear inch in diameter
  • Fastening shall be completed fully during application of each sheet and not tacked for later return
  • Panels shall be spaced 1/8 linear inch at all edges – both side and end  

Comment:  Nailing guidelines for roof sheathing follow for scheduling.

1.       FASTENERS SHALL BE APPLIED AFTER NOT LESS THAN ½ LINEAR INCH DIAMETER CONTINUOUS 2 BEADS OF CONSTRUCTION ADHESIVE HAS BEEN APPLIED TO SUBORDINATE FRAMING MEMBER FACES TO WHICH SHEATHING IS TO BE APPLIED.  FASTENERS SHALL BE APPLIED COMPLETELY OVERALL TO EACH GIVEN SHEET BEFORE PROCEEDING WITH APPLICATION AND FASTENING OF ANOTHER SHEET.  ADHESIVE SHALL CONFORM TO NOT LESS THAN AMERICAN SOCIETY FOR TESTING AND MATERIALS ASTM D3498, "ADHESIVES FOR FIELD-GLUING PLYWOOD TO LUMBER FRAMING FOR FLOOR SYSTEMS" (INCLUDING HUD-FHA USE OF MATERIALS BULLETIN UM60A) AND AMERICAN PLYWOOD ASSOCIATION AFG-01 "ADHESIVES FOR FIELD-GLUING PLYWOOD TO WOOD FRAMING"

2.       Wood Structural Panels (Plywood). To 1" thick. Nailing Pattern: 4" on center at panel edges over continuous members and double nailed at edges with crossing members, and 6" on center in field. Nail: 2.50"x 0.131" (8d common); 2.50"x 0.131" deformed shank; 2.50"x 0.120" deformed shank; 3"x 0.120" deformed shank; 3"x 0.128" (10d box); 3"x 0.131"; 3.25"x 0.131".

3.       Spaced Boards to Rafters. 1 Nail: 2.50"x 0.131" (8d common); 2.50"x 0.131" deformed shank; 2.50"x 0.120" deformed shank; 3"x 0.120" deformed shank; 3"x 0.128" (10d box); 3"x 0.131"; 3.25"x 0.131".

4.       Wood Structural Panels (Plywood). 1" thick or less (Applied Over Spaced Boards). 1 Nail per board, 4" on center at edges, over continuous members and double nailed at edges with crossing members, and 6" on center in field: 3"x 0.128"; 3.25"x 0.128" (12d box); 3"x 0.120" deformed shank; 3"x 0.131"; 3.25"x 0.131".   

EXTERIOR WALL SHEATHING TO FRAME

• Wall sheathing shall be
  • Not less than 5/8 linear inch CDX plywood shall be applied as wall sheathing
  • With face grain perpendicular to rafters or top chords and
  • Arranged so that the narrower butts equally share a rafter's nailing surface

• Wall sheathing edges shall extend to fully cover (less spacers) bottom plates, including mud sills, and top plates in a single-story structure

• Wall sheathing edges shall extend beyond bottom plates and onto studs at the second story of a two-story structure, i.e., shall overlap structure of both floors

• Applied noting that all exposed seams, i.e., not parallel with stud vectors, shall be fully blocked with sisters, to which sheathing shall be adhered and screwed or nail-fastened  

• Plywood applied as exterior wall sheathing shall be classified Exterior Exposure, not Exposure 1 and not Exposure 2

Comment:  This custom home designer is personally indifferent as to sheets' orientation – horizontal or vertical – so long as every open seam, or joint, is fully blocked with a 2x sleeper, adhered and nailed or screwed on both seam's edges.

• Guidelines for fastening sheathing to frame walls follows-  

Not For Lateral Resistance - Interior  

1. FASTENERS SHALL BE APPLIED AFTER NOT LESS THAN ½ LINEAR INCH DIAMETER CONTINUOUS 2 BEADS OF CONSTRUCTION ADHESIVE HAVE BEEN APPLIED TO EACH SUBORDINATE FRAMING MEMBER'S FACE TO WHICH SHEATHING IS TO BE APPLIED.  FASTENERS SHALL BE APPLIED COMPLETELY OVERALL TO EACH GIVEN SHEET BEFORE PROCEEDING WITH APPLICATION AND FASTENING OF ANOTHER SHEET.  ADHESIVE SHALL CONFORM TO NOT LESS THAN AMERCAN SOCIETY FOR TESTING AND MATERIALS MOST RECENT ASTM D3498, "ADHESIVES FOR FIELD-GLUING PLYWOOD TO LUMBER FRAMING FOR FLOOR SYSTEMS (INCLUDING HUD-FHA USE OF MATERIALS BULLETIN UM60A)  
2. Wood Structural Panels (Plywood), To .50" thick. Nailing Pattern: 4" on center along panel edges and 6" on center in field. 1 nail: 2"x 0.113" (6d common); 2"x 0.113" deformed shank; 2.50"x 0.113" (8d box); 2"x 0.113"; 2"x 0.113" deformed shank; 2.50"x 0.120" deformed shank; 3"x 0.120"; 3"x 0.120" deformed shank; 3.25"x 0.120"; 2.50"x 0.131"; 2.50"x 0.131" deformed shank; 3"x 0.131"; 3.25"x 0.131".  
3. Wood Structural Panels (Plywood), over .50" thick. Nailing Pattern: 4" on center along panel edges and 6" on center in field. 1 nail: 2.50"x 0.131" (8d common); 2.50"x 0.131" deformed shank; 2.50"x 0.120" deformed shank; 3"x 0.120"; 3"x 0.120" deformed shank; 3"x 0.128" (10d box); 3"x 0.131"; 3.25"x 0.131"

Not For Lateral Resistance - Exterior

1. FASTENERS SHALL BE APPLIED AFTER NOT LESS THAN ½ LINEAR INCH DIAMETER CONTINUOUS 2 BEADS OF CONSTRUCTION ADHESIVE HAVE BEEN APPLIED TO EACH SUBORDINATE FRAMING MEMBER'S FACE TO WHICH SHEATHING IS TO BE APPLIED.  FASTENERS SHALL BE APPLIED COMPLETELY OVERALL TO EACH GIVEN SHEET BEFORE PROCEEDING WITH APPLICATION AND FASTENING OF ANOTHER SHEET.  ADHESIVE SHALL CONFORM TO NOT LESS THAN AMERICAN SOCIETY FOR TESTING AND MATERIALS ASTM D3498, "ADHESIVES FOR FIELD-GLUING PLYWOOD TO LUMBER FRAMING FOR FLOOR SYSTEMS" (INCLUDING HUD-FHA USE OF MATERIALS BULLETIN UM60A) AND AMERICAN PLYWOOD ASSOCIATION AFG-01 "ADHESIVES FOR FIELD-GLUING PLYWOOD TO WOOD FRAMING"  
2. Wood Structural Panels (Plywood), lapping panels to band butts not less than 2"x joist spacing and lapping panels from field and onto plates. Nailing Pattern: 4" on center along panel edges over continuous members (including on center to each of the double top plates) and double nailed at edges with crossing members and 6" on center in field, and rows of not less than 3 on row not greater than 6" on center to band joists: 1 Nail: 2.50"x 0.131" (8d common); 2.50"x 0.131" deformed shank; 2.50"x 0.120" deformed shank; 3"x 0.120" deformed shank; 3"x 0.128" (10d box); 3"x 0.131"; 3.25"x 0.131".

For Lateral Resistance - Interior or Exterior  

1. FASTENERS SHALL BE APPLIED AFTER NOT LESS THAN ½ LINEAR INCH DIAMETER CONTINUOUS 2 BEADS OF CONSTRUCTION ADHESIVE HAS BEEN APPLIED TO SUBORDINATE FRAMING MEMBER FACES TO WHICH SHEATHING IS TO BE APPLIED.  NAILING SHECDULES SHALL BE NOT LESS THAN AS ABOVE FOR NON-RESISTANT WALL SHEATHING, EXCEPT FOR SHEAR WALL APPLICATION AT 3 LINEAR INCHES ON CENTER OVERLAL.  FASTENERS SHALL BE APPLIED COMPLETELY OVERALL TO EACH GIVEN SHEET BEFORE PROCEEDING WITH APPLICATION AND FASTENING OF ANOTHER SHEET.  ADHESIVE SHALL CONFORM TO NOT LESS THAN AMERICAN SOCIETY FOR TESTING AND MATERIALS ASTM D3498, "ADHESIVES FOR FIELD-GLUING PLYWOOD TO LUMBER FRAMING FOR FLOOR SYSTEMS" (INCLUDING HUD-FHA USE OF MATERIALS BULLETIN UM60A) AND AMERICAN PLYWOOD ASSOCIATION AFG-01 "ADHESIVES FOR FIELD-GLUING PLYWOOD TO WOOD FRAMING"  

SHEAR WALL TO FRAME

• When acting as shear wall
  • Shear wall sheathing shall be
    • Not less than 5/8 linear inch, Structural 1 plywood
    • Applied in a vertical orientation only  

Comment:  This prescript on verticality seems parochial to this custom home designer so long as seams, or joints, are full-depth, solid-blocked and appropriately fastened; however, this designer has yet to observe a shear wall presentation done by others that had a sheet orientation other than axially vertical.

• Shearwall
  • Shall be fastened
    • At 3 linear inches on-center to each top plate
    • At 3 linear inches on-center to each king stud and jack stud, or jamb stud, or trimmer stud
    • At 3 linear inches on center in rows to the header
    • On not greater than 4 linear inch centers
    • At not less than ½ linear inch in from sheathing perimeters
    • Without application of construction adhesive at joints with members
    • At joints to other sheathing
      • With galvanized wood screws, not nails
        • Driven only perpendicular (i.e., only straight) to a shear wall plane
        • Not overdriven
    • Only after approval of fastener materials and methods by engineer, inspector, and contractor
    • For inspection before wrapping the house
  • Shall have adjoining, narrow-end butts aligned not more closely than 2 studs between   

• Shear wall shall be sheathed
  • Separated with framing clips
  • Fastened
    • Directly to a member
    • Firmly and without bending and gapping to a member
    • With the full complement of nails or screws prescribed by the manufacturer
  • Applied in lieu of toed nails in fastening blocks and end and head joists, or rim boards, to subordinate structure
  • At plates, whereat nails shall be applied one size above that specified for nonshear wall application  

Comment: For a lot more on shear walls, notably including framing, anchoring, and bracing, please see hereunder "Shear Wall Details - Home Design and Construction Details" at http://searchwarp.com/swa323083.htm
 

SHEAR WALL ADAPTATION

Comment:  Recently, BTA was commissioned to design a home in seismic zone 2A, close to 2B, in turn, close to the New Madrid Fault.  Some local building codes were noticeably written to allay some concerns about structural viability in seismicity – bracing open web, metal plate-connected wood truss floor in certain aspects, for example.  The clients requested that interior walls most subject to bearing at L0 (of a 3 level structure) be shear walled as well.  BTA applied the same materials and methods to the LI bearing walls as on would have been for exterior shear walls; thereafter, finish cladding with ½ linear inch gypsum board or 5/8 line inch Type-X as needed.  BTA prepared a separate plan view of L0 to highlight applications, with cross-reference to Floor Plan, L0.

SHEETROCK TO WOOD STRUCTURE

Comment:  Sheetrock is a/k/a wallboard, gypsum board, gyp board, rock, etc.

• Wallboard fastened to ceiling
  • Where the ceiling structure is of roof truss or floor truss bottom chords and
    • Especially in colder climes and
    • Without regard as to whether the attic above is vented or unvented
  • Shall be
    • Fastened to the bottom chords to within 18 linear inches of space perimeters
    • Not fastened to the bottom chords within 18 linear inches of space perimeters
    • Supported at its perimeters by clips
  • May require cornice trim to conceal ceiling creep evidenced at the perimeters by expanding and contracting joints between the seasons  

• Guidelines follow for fastening gypsum board to frame walls –   

1. FASTENERS SHALL BE APPLIED AFTER NOT LESS THAN ½ LINEAR INCH DIAMETER CONTINUOUS 2 BEADS OF CONSTRUCTION ADHESIVE HAS BEEN APPLIED TO SUBORDINATE FRAMING MEMBER FACES TO WHICH SHEATHING IS TO BE APPLIED.  FASTENERS SHALL BE APPLIED COMPLETELY OVERALL TO EACH GIVEN SHEET BEFORE PROCEEDING WITH APPLICATION AND FASTENING OF ANOTHER SHEET.  ADHESIVE SHALL CONFORM TO NOT LESS THAN AMERICAN SOCIETY FOR TESTING AND MATERIALS ASTM C557, "ADHESIVES FOR FASTENING GYPSUM WALLBOARD TO WOOD FRAMING" OR  ASTM D6464, "EXPANDABLE FOAM ADHESIVES FOR FASTENING GYPSUM WALLBOARD TO WOOD FRAMING".  NOTE WELL THAT ADHESIVE SHALL NOT BE APPLIED TO FASTEN WALLBOARD TO FRAMING IN SEISMIC ZONES 2B AND UP. 
2. APPLIED ONLY WHEN ABSOLUTELY NECESSARY: Sheetrock nails (10d, minimum 10 diameters penetration into structure):  To a wall with adhesive applied as fastener), 12" on center at perimeter and 12" on center in field; To a wall without adhesive applied as fastener, 6" on center overall. 
3. APPLIED ONLY WHEN ABSOLUTELY NECESSARY: Sheetrock nails (10d, minimum 10 diameters penetration into structure): To a ceiling with adhesive applied as fastener, 12" on center at perimeter and 12" on center in the field; To ceilings without adhesive applies as fastener, 6" on center overall. 
4. Sheetrock Screws (not less than 5/8" penetration into structure): To walls of 16" on center framing with or without adhesive applied as fastener, 16" on center overall; To walls of (prohibited) 24" on center framing with adhesive applied as fastener, 12" on center overall. 
5. Sheetrock Screws (not less than 5/8" penetration into structure): To ceilings of 16" on center framing or (prohibited) 24" on center framing with or without adhesive applied as fastener, 12" on center overall.