Wall Construction

WRCLA Cedar Siding

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. Maximum spacing for furring strips is 16 inches on center. Spacing for furring strips should match the spacing of the studs.

Vertical siding applications require horizontal nailers, blocking or other wood framing members spaced no more than 24 inches on center. Check your building code to verify requirements in your area.

Lumber Size and Spacing for Blocking and Furring¹
	Nominal Size (inches)	Actual Size (inches)	Preferred Spacing (inches)	Maximum Spacing (inches)
Blocking	2x2	1-1/2 x 1-1/2	16	24
Furring over plywood/OSB sheathing²	1x2	3/4x1-1/2	16	24
Furring over masonry walls	2x2	1-1/2x1-1/2	16	24

1. Furring must be securely fastened to studs.
2. Can be used in moist and severe climates to form an air space between siding and sheathing (ie. rainscreen).

Rainscreen Construction

The basic rainscreen wall configuration, incorporating two layers, or wythes, separated by an air space, has variations that provide different levels of rain protection effectiveness. A distinction should be made between the drained cavity wall, the simple or open rain screen, and the pressure-equalized rain screen wall. What is usually meant by a “rain screen wall” is generally the latter: an exterior cladding, a cavity behind the cladding, drained and vented to the outside; an inner wall plane incorporating an air barrier; and a set of compartment seals limiting the cavity size. The outer “screen” layer of cladding deflects the kinetic force of the rain, while the inner wythe remains protected. The vented cavity uses gravity and flashings to drain water that penetrates the outer wall, away from vulnerable surfaces and joints. The cavity is sufficiently wide that surface tension and capillary action are not able to move water across the cavity.

Step by step construction tips for basic rainscreen construction (check with local building codes for the appropriate techniques in your area):

Drill hoes (approximately 1") in the exterior wall sheathing (if plywood or OSB sheating is used) to permit residual moisture to escape.
Install gas permeable housewrap (such as DuPont Tyvek’s Drainwrap) or building paper.
Install vertical furring strips. Ensure they are lined up with the studs.
Install screen materials under the ends of the furring strips. Fold the screen material over the furring strips and staple to the front of the furring strips.
Install Western Red Cedar siding over the furring strips.

More information about rainscreen construction techniques is available from Canada Mortgage and Housing Corporation.

Masonry Walls

Masonry walls require furring strips for horizontal and vertical siding installation. Furring strips must be thick enough to allow for nail penetration of 1¼ inches into solid wood.

Structural Insulated Panels (S.I.P.)

Structural Insulated Panels require furring strips for horizontal and vertical siding installation. Furring strips must be thick enough to allow for nail penetration of 1¼ inches into solid wood. Typical Structural Insulated Panels have nominal ½ inch sheathing. To ensure the appropriate nailing base, furring strips a minimum of ¾ inch thick should be installed on the outside of the sheathing at a maximum of 16 inches on center.

Insulated Concrete Forms (I.C.F.)

These systems have no wood component and the foam has no nail holding capacity. As a result, Insulated Concrete Forms require framing of a minimum of 1¼ inches thick spaced 16 inches on center on the outside of the foam. Note these will need to be securely fastened to the concrete.

Rigid Foam Sheathing

Rigid foam sheathing has an insulation value superior to that of traditional lumber and plywood sheathings. However, it has no nail holding power and using rigid foam sheathing as a nailing base for cedar siding is not recommended. Follow the nailing recommendations given in this publication as to nail type, positioning, penetration and spacing.

Foam sheathing panels vary in moisture permeability but are generally considered as good moisture barriers. They should be used with a continuous film vapor retarder on the inside wall under the interior finish. Rigid foam sheathing can cause moisture to accumulate on the back of siding and cause staining, buckling and damage to finish coats. As a result, it is recommended that furring strips are used to create an air space between the sheathing and siding (follow the rainscreen construction method).

Other recommendations that should be followed to minimize potential problems:

Thick, narrow siding is more stable than thinner, wider patterns and better able to resist dimensional changes.
Use kiln-dried siding over rigid foam sheathing. This is the most stable cedar siding.
Proper prefinishing is essential.
Use light color finish coats to maximize heat reflection and reduce dimensional movement.
In all cases it is strongly recommended that gas permeable house wrap, such as DuPont Tyvek DrainWrap, be applied over the foam sheathing.

Installing & Finishing

Cedar Siding

Quotes

For optimum performance, the WRCLA recommends that Western Red Cedar is preprimed or pre-finished prior to job site delivery.
Western Red Cedar produces fewer greenhouse gases, generates less water and air pollution, requires less energy to produce than alternatives and comes from a renewable and sustainable resource.
Western Red Cedar from WRCLA members is independently certified as legal and sustainable.
• Western Red Cedar requires significantly less energy to produce than fibre cement or wood composite materials.
Unlike man-made alternatives, Western Red Cedar is biodegradeable.
Western Red Ce¬dar has the lowest environmental impact when compared with other materials such as brick and fibre cement.
The Western Red Cedar Lumber Association (WRCLA) is non profit association representing Western Red Cedar producers, distributors and retailers throughout North America.
Western Red Cedar is one of the most durable coniferous species and can be counted on to give long and trouble free service under most conditions.
Western Red Cedar is light weight, easily worked and ideal for almost all types of finishes.
Western Red Cedar has centuries of proven performance which cannot be said of new man made products.
The Life Cycle Assessment (LCA) of Western Red Cedar siding and decking shows it has the lowest overall environmental impact when compared with brick, vinyl and fibre cement siding.
Western Red Cedar is free of pitch and resin which makes it an excellent base for protective coatings.
Western Red Cedar has 400 times better insulation (R) value than steel, 2000 times that of aluminum, 8 times that of concrete.

For wood decking information visit www.cedar-decking.org|For wood fence, fencing, gazebo and arbor info visit www.cedar-outdoor.org