Installation Manual - CertainTeed

CertainTeed WeatherBoards Fiber Cement Siding Installation Manual
Butt and End Joint Application
There are three ways to fasten butt and end joints:
1. Into solid framing
2. Into structural sheathing
3. With an off-stud joiner
Butt End/Joints Fastened into Solid Framing
or Structural Sheathing
Butt end/joints should be installed with factory-sealed
or factory-prefinished ends butted together in moderate
contact. We recommend that butt end/joints be fastened
into a stud or framing member. If no stud or framing
member is available, butt end/joints may be fastened into
structural-rated sheathing.
When installing WeatherBoards lap siding, you must
install butt joints using either backflashing, joint covers,
or H-covers. Consult local code for butt joint treatment
requirements in your area. Backflashing should be
constructed of a durable, non-corrosive material that is
compatible with fiber cement. Do not attempt to flash
behind end or butt joints with housewrap—housewrap
will not direct water away from the wall. Flashing size
should be a minimum of 6" wide (3" to the left and right
of the joint) and extend at least 1" over the top of the
previous course. Examples of butt end/joint flashing
materials include:
X X#15
felt
XXTrim coil (painted or PVC coated)
XXBear Skin Joint Flashing
Joint
flashing
extends
3" to left
and right
of joint and
overlaps
the previous
course by 1"
Butt End/Joint Application: Fastening to structural sheathing
36
Structural sheathing
Overlap
flashing 1"
Overlap boards
1- 1/4"
Nail 1" from
board top;
nail 1" from
butt edge
and 3" from
butt edge
Some flashing manufacturers, including Simplicity Tool
and ProTrim, make joint flashing products that do not
extend 1" over the top of the siding. They rest on top of
the lap. These products are also acceptable.
If you choose to use a non-factory end at a butt joint, the
side edges must be re-sealed with 100% acrylic latex
paint or primer prior to installation.
NOTE: Fiber cement siding should be fastened to
framing. If no stud is available, place two fasteners
2" apart into structural rated sheathing (7/16" OSB
or 1/2" plywood).
Fastening to Stud or Framing Member: Place one
fastener 1" below the top of the board and no closer than
3/8" from the butt edge into the stud.
Fastening to Structural Sheathing: Place one fastener
1" below the top of the board and 1" from the butt edge.
Place another fastener 3" from the butt edge.
Butt End/Joint Application
Studs 16"– 24"
o.c. max
Joint
flashing
extends
3" above
board and
3" to left
and right
of joint
Overlap
flashing 1"
Overlap
boards 1- 1/4"
Fastening to stud or framing member
NOTE: It is never acceptable to leave a gap of any
size at a butt end/joint.
Nail 1"
from
board
top