I called it a complexly designed home.
The home design was what the clients needed and wanted. I called it tight. My
clients asked me what that meant. I told them that once the slab-on-grade
cured, they should be at the building site every morning early to make sure that
the master carpenter showed up well slept and sober, or there'd be several homes
built on that slab before he got the one we'd drawn. Before The Architect
INTRODUCTION
This is about house sheathing - roof sheathing, wall sheathing, exterior wall
sheathing and shearwall construction
This is not about foam board
PERSPECTIVE
House sheathing is the last major player in securing a
fine 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
Foundation to earth
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".
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 dream 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 - interiors
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 MOST RECENT ASTM D3498,
"ADHESIVES FOR FIELD-GLUING PLYWOOD TO LUMBER FRAMING FOR FLOOR SYSTEMS
(INCLUDING HUD-FHA USE OF MATERIALS BULLETIN UM60A)
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".
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 - Exteriors
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"
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 - Interiors or Exteriors
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 SCHEDULES SHALL BE NOT LESS
THAN AS ABOVE FOR NON-RESISTANT WALL SHEATHING, EXCEPT FOR SHEAR WALL
APPLICATION AT 3 LINEAR INCHES ON CENTER OVERALL. 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 DESIGN, SHEARWALL CONSTRUCTION
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 dream 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
construction
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 residential 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
SHEAR WALL ADAPTATION
Comment: Recently, BTA was commissioned to design a
dream 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.
DRYWALL OR SHEETROCK WOOD STRUCTURE
Comment: Sheetrock is a/k/a wallboard, gypsum board, gyp
board, rock, etc.
Dry wall 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 –
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.
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.
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.
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.
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.
(If this is your first visit to Before The
Architect, please consider spending a few moments looking over the
Site
Map, in design of a custom home, plans, the home designers, about builders and building.
Before The Architect E-mail:
jrp2h2000@yahoo.com.)
