Installation Guide

5
weeks weathers enough to reduce
the adhesion of film-forming
finishes.
Priming or prefinishing the siding
(all sides, edges and cut ends)
after it has reached climatic
balance but before it is installed
can provide extra protection and
often prevent adhesion problems
and/or premature finish failure.
Back-priming the siding eliminates
the leaching of chemical extractives,
which have the potential to degrade
sheathing wraps.
Prefinishing is recommended in all
circumstances. Prefinishing will min-
imize objectionable unfinished lines
where joints open up due to face-
width shrinkage during exceptionally
dry summers.
Make certain the prefinish is com-
patible with the final coat. For
example, clear water repellents
should not be used if a bleaching
oil is to be the final finish. (Refer to
the Finishing section.)
Installation
Natural wood siding should be
installed over a weather-resistive
barrier
regardless of the sheathing
material. A weather-resistive barrier
is a vapor-permeable sheathing
wrap that resists any liquid water
that gets behind the siding, and
acts as a drainage plane. There are
three basic types of sheathing
wrap: asphalt felt, Grade D building
paper and plastic housewrap. In
order to function as a drainage
plane, a sheathing wrap should
have an air gap between the wrap
and the siding. (An appropriate
vapor barrier, on the warm side of
the insulation, should be used to
reduce moisture movement from
inside.) (See Figure A.)
Sometimes referred to as a “rain-
screen” wall, the air space behind
the exterior siding promotes
drainage and ventilation, and allows
the drainage plane surface to shed
water back to the exterior rather
than absorb it. Typically, a 1/8-in. to
1/2-in. air space between the
Figure B: CORNER DETAILS
Figure A: FURRING STRIPS AND
DRAINAGE PLANE
Inside Corner Detail-b
a. HORIZONTAL SIDING
b. BUILDING PAPER
c. METAL FLASHING OR BUILDING PAPER
d. USE CAULK AT INSIDE CORNER OR
OPEN JOINT. PROVIDE METAL FLASHING
BEHIND JOINT IF CAULK IS NOT USED.
e. SHEATHING
a
c
b
e
d
Outside Corner Detail-b
a. PROVIDE ADDITIONAL STUD TO ALLOW
FOR NAILING AT ENDS OF SIDING
b. BUILDING PAPER
c. CAULK
d. CORNER BOARDS
e. SHEATHING
b
b
d
d
a
c
e
a
b
c
b
a. HORIZONTAL SIDING
b. BUILDING PAPER
c. TRIM
d. SHEATHING
e. CAULK
d
e
Inside Corner Detail-a
Outside Corner Detail-a
a. HORIZONTAL SIDING
b. BUILDING PAPER
c. CAULK
d. CORNER BOARDS
e. SHEATHING
a
b
b
d
e
d
c
a. STUD
b. SHEATHING
c. BUILDING PAPER OR HOUSEWRAP
d. PRESSURE-TREATED OR NATURALLY
DURABLE FURRING STRIP
e. HORIZONTAL SIDING
f. DRAINAGE MAT WITH INSECT BARRIER
a
b
c
a
e
f
d
d