This article discusses best construction practices for wood shingle wall siding installation, including wood shingle types, grades, nailing requirements, application patterns, coatings & stains.
This article series discusses best practices construction details for building exteriors, including water and air barriers, building flashing products & installation, wood siding material choices & installation, vinyl siding, stucco exteriors, building trim, exterior caulks and sealants, exterior building adhesives, and choices and application of exterior finishes on buildings: paints, stains.
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Adapted/paraphrased with permission from Best Practices Guide to Residential Construction. Steven Bliss. [Click to enlarge any image]
This article series discussion includes Wood shingle siding underlayment requirements. Wood shingle siding nailing details. Wood Shingle Single-Coursing Installation Details for Walls. Wood Wall Shingle Double-Coursing Installation Details. Wood Wall Shingle Clearance at Flashings. Wood Wall Shingle Installation. Details for wood shingled Building Corners. Panelized Wood Wall Shingle Installation. Wood Shingle Stains & Finishes, Effects of xterior Finishes on Wood shingle siding: moisture, surface prep, paint choices, solid color stains, paint & stain application details, discoloration, semitransparent penetrating stains, clear & light-tint finishes, bleaching oils
Cedar shingles and shakes are a popular choice for sidewall applications in coastal regions. Eastern white cedar shingles are often left unpainted in New England coastal areas.
Red cedar shakes are often left unpainted on the West Coast. Red cedar shingles are sometimes left natural, but more often are painted or stained.
Our wood shingled home photographs here demonstrate red cedar shingles exposed in two different exposure lengths, an aesthetic choice made by our associate Paul Galow.
Sidewall installation is similar for shakes and shingles with some variation in exposure (see Table 1-5).
Red cedar shingles come in four grades, but most sidewalls use grades No. 1 or No. 2. No. 1 is all heartwood and all edge-grain wood.
Red cedar shingles are available rebutted and rejointed (R&R) where a uniform appearance is desired and machine grooved for a textured surface. Red cedar shakes come either taper-split or untapered and are usually installed in Premium or No. 1 grade (see Table 1-6).
Eastern white cedar shingles are available in four grades. Most sidewall work on building exteriors uses Grade A (Extra), which is all clear heartwood, or Grade B (Clear), which has no knots on the exposed face (see Table 1-7).
The simplest and most common pattern for sidewall shingles and shakes is single coursing. For wider exposures and deeper shadow lines, shingles and shakes can also be installed in double courses. A rustic staggered pattern is also possible.
The Cedar Shake and Shingle Bureau recommends installation over Type 30 asphalt felt underlayment for red cedar shingles and shakes. Install the felt paper with minimum 6-inch overlaps on vertical joints, 2 inches on horizontal laps, and 4 inches wrapped each way at inside and outside corners. Creasing the felt at corners will help achieve a tight fitting corner.
For optimal performance, manufacturers of Eastern white cedar shingles now recommend installation over horizontal furring spaced equal to the shingle exposure or over a ventilating layer such as Benjamin Obdyke’s Home Slicker®. They acknowledge that most sidewall installations still go directly over the wall sheathing covered with felt paper or plastic housewrap.
Field experience suggests that an air space or drainage/ventilation layer is critical for longevity on roofs, but on sidewalls, good quality white cedar shingles perform adequately without these extra steps.
The first course of shakes or shingles is doubled, with the outer course dropped 1/2 inch lower to create a drip edge (see Figure 1-14, at left).
Tack up a length of 1x3 furring as a guide for the next course, moving up the wall with each successive course.
To create a weather-tight exterior, do not exceed the exposures shown in Table 1-5 above.
Red Cedar Wall Shingles: Space No. 1 red cedar shingles 1/8 to 1/4 inch apart to prevent possible buckling.
A 1/4-inch space is recommended for No. 2 R R& R red cedar shingles.
White cedar shingles should be spaced from 1/16to inch apart depending on conditions — a 1/16 -inch gap would be appropriate for green shingles, which are prone to shrinkage, and a 1/4-inch gap for kiln-dried shingles installed in a moist environment.
Also, offset joints in successive shake or shingle courses by at least 1 1/2 inches as shown in Figure 1-15.
Treat knots and other defects like an edge and offset adjacent courses at least 1 1/2 inches.
With white cedar shingles, also make sure that two joints do not align if separated by only one course.
For increased exposures and deeper shadow lines with red cedar shingles or shakes, apply in double courses, as shown (Figure 1-16).
Despite the greater exposures, considerably more material and labor are required.
Installation of wood shingles on a building wall starts at the bottom with a triple layer and succeeding layers are doubled as shown.
Use corrosion-resistant box or casing nails of either stainless steel, hot-dipped galvanized, brass, or aluminum. For concealed nails, hot-dipped galvanized are adequate. For exposed nails at corners and under eaves and windows, stainless steel, brass, or aluminum are less likely to stain the wood.
For red cedar shingles and shakes, nail 2 inches above the butt line and 3/4 inch in from each end. C
edar shingles wider than 10 inches need two additional nails driven 1 inch apart near the center of the shingle. Nails should fully penetrate the sheathing (see Table 1-8below). Aluminum or stainless-steel staples with 7/16-inch to 3/4 -inch crowns are also an option for red cedar shingles if accepted by local codes.
White cedar shingles are nailed 1-1/2 inch above the butt line and 3/4 inch in from each end. Manufacturers recommend a 1-1/4 inch (3d) box or shingle nail for new construction and a 1-3/4 inch (5d) nail when going over another siding material. Drive nails flush with the surface. Do not overdrive and set the nails or leave them projecting from the surface.
Most sources including those we list below specify two nails per wood shingle.
Here is what the USDA says about wood shingle nailing - notice that the spacing from each end is handled differently:
Nail placement for cedar shingles up to 10 in. (254 mm) wide requires two corrosion-resistant nails driven 3/4 in. (19 mm) from each edge and 1 in. (25 mm) above the exposure line. For shingles wider than 10 in. (254 mm), drive two additional nails approximately 1 in. (25 mm) apart near the center.
To decrease the chance of splitting the shake/ shingle, fasteners should be blunted siding nails and should be ring-or twist-shank to improve holding. A ring-shank nail will have adequate holding power if it penetrates ¾ in. (19 mm) into the wood. Corrosion-resistant nails are needed to avoid iron stains caused by extractives in the wood and corrosion by acid rain, salt air, etc. - USDA cited below.
USDA as well as typical manufacturer installation instructions for wood shingles specify two nails per shingle.
Keep all shingle bottoms a minimum of 1/2 inch above the lower leg of any flashings to minimize the wicking of water, which can lead to staining and possible decay.
Our wood shingle photos below show two methods of fitting inside wall corners.
As extra protection, it is a good idea to add a layer of flashing or No. 30 felt paper at inside and outside corners.
If felt is used, crease it at corners for a tighter fit.
A simple, attractive inside corner can be achieved by butting the shingles to a 5/4-inch square cedar strip nailed into the corner (Photo, right).
Below our photographs show two wood shingle details for constructing outside wall corners, also demonstrated in the sketch above.
For fast and simple outside corners, butt the shingles to corner boards made from 1x or 5/4 stock (see Figure 1-17 above and our photo just above).
Another more labor-intensive approach is to “weave” inside and outside corners by alternating two shingles on one side with two on the other (photo, above). On an outside corner shingled this way, the exposed edge alternates every course.
To keep outside corners tight, nail through the butts with a small hot-dipped galvanized finish nail. On woven inside corners, alternating courses keep the joints tight.
To simplify and speed up installation, several manufacturers offer sidewall shingles attached to panels with either staples or adhesive (see Figure 1-18).
The wood shingle panels range from one-course panels 32 inches wide to three-, four-, and five-course panels 2 feet wide by 8 feet long, including panels with decorative patterns.
Some wood siding shingle manufacturers also offer prefabricated inside and outside corners, radiused panels for curved walls, column wraps, and other types of labor-intensive details.
Eastern white cedar shingles are often left unfinished and tend to weather to an attractive silver gray—particularly with exposure to sun and salt air in coastal climates. However, splashback and other uneven weathering conditions can lead to dark streaks or splotches (photo, below left, Hudson Valley, NY).
To accelerate the weathering process and to guarantee uniformity of color, a bleaching oil is recommended. For a pigmented finish, use an oil-based, semitransparent stain. Prefinished white cedar shingles are available with a stained finish or pretreated with bleaching oil.
If left unfinished, red cedar shingles will tend to weather to a dark reddish-brown color. (See our photo above right, Two Harbors MN) To guarantee uniformity of color, red cedar shingles should be finished with an oil-based clear finish, oil-based stain, or bleaching oil.
If a painted finish is desired, use an oil-based primer with a 100% acrylic top coat for best results. Factory finished shingles and shakes are available pre primed or pre stained, ready for a top coat after installation. See more under “Exterior Wood Finishes” (page 42 in Best Practices Guide cited below).
-- Adapted with permission from Best Practices Guide to Residential Construction.
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(Aug 18, 2011) Karl Garson said:
I'm after a 4-inch exposure with 18-inch cedar shingles. But in doing a dry run on a flat horizontal surface my successive double courses keep getting thicker and thicker. What am I doing wrong? The known factor here is that I am doing something wrong.
Karl, I don't think you're doing anything wrong; a 4-inch exposure on an 18-inch single means that you'll have 4 1/2 shingles of exposure going up the roof (or up a wall) before your next shingle is past the head of the very first shingle. That gives a very thick surface indeed. When the whole wall is in place it'll be flat - thick - and probably durable.
(Feb 13, 2012) Alan Dawson said:
I am considering doing shingles on a brick gable end wall would you need to panel it out in 8x4ft sheets ply first allowing you a fix to the wall?
I'd install furring and a housewrap.
Nov 17, 2012) forrest S said:
I'm looking for metal corner guards that fit over WOVEN outside corners with a 13in exposure. Any thoughts?
Woven outside corners, by design, don't use a corner board. If you want to nail top the woven corners you can do so but I'd hold a board up on the corner to look: you may not like how it appears nor the gaps that will show.
(May 27, 2014) Les said:
I am using Certigrade 1 Blue Lable red cedar shingles. Both sides of each shingle appear the same. Does it matter which side of the shingle is faces up?
If these are sawn shingles (not shakes) it should not matter. Check the shingles: if one side shows rough saw kerf marks and the other does not, place the kerf marks facing in towards the building.
(July 19, 2014) Anonymous said:
I'm doing a plywood repair under cedar shake siding ---which was put over lapboard--can I double up with exterior plywood to bring the siding out to flush or do I have to fir strip for backing ?
You can attach plywood to the existing wall - find and nail or screw into the studs.
What construction adhesive works with shingles - Ed.
Ed, I've thought about it and don't have an immediate suggestion that is perfect, but your best bet is to use a quick-setting construction adhesive such as Liquid Nails polyurethane construction adhesive LN-950, or one of the Loctite construction adhesive products with a quick set time, that remains a bit flexible, and is rated for outdoor use.
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