Installation Guide
Vapor barrier
Stud
Insulation
Strapping
Sheathing
House Wrap
(eg. Tyvek®
DrainWrap™)
Real Cedar
Siding
Flashing
Real Cedar
Bandboard
7. CONTROLLING MOISTURE: VAPOR BARRIERS AND BUILDING PAPER
High humidity output from washers, dryers, showers, kitchens and other sources, combined with today’s
energy-efcient construction, can result in a build-up of interior moisture vapor. This vapor migrates through
the fabric of a building from the warm interior to the cold exterior, and when it condenses to water can cause
structural damage and damage to sidings and nishes. Vapor barriers installed on the warm side of the wall
largely prevent the migration of moisture vapor but they are not perfect. Residual vapor must be allowed
to escape to the outside. Housewrap installed on the outside face of the sheathing helps prevent rain and
snow from penetrating the walls but allows the escape of moisture vapor. The WRCLA recommends the use
of rainscreen wall construction (see diagram and related section later in this publication) especially when installing
over rigid foam.
Proper wall construction includes the use of breathable or gas permeable housewrap (such as DuPont™ Tyvek®
DrainWrap™) or building paper and interior vapor barriers. These are extremely effective in helping to prevent
moisture problems.
8. WALL CONSTRUCTION
Stud Walls
Like all siding materials, Western Red Cedar performs best when installed properly on a suitable frame. Cedar
siding should be securely nailed to framing members, furring members or to blocking between framing members.
Standard stud walls generally require no special preparation for horizontal siding installation. Siding should be
nailed into studs or blocking at maximum of 24 inches on center when applied over wood based sheathing and
16 inches on center when siding is installed without sheathing. In instances where an air space between siding
and sheathing is desired (see rain screen wall construction), nail siding to furring strips, sheathing and framing.
Maximum spacing for furring strips is 16 inches on center. Spacing for furring strips should match the spacing of
the studs.
BEFORE YOU START
WESTERN RED CEDAR
SIDING
6
Minimum 6” Clearance
From Ground Level