Attachment_1_-_Cedar_Shake_and_Shingle_Bureau_Roof_Manual_2020.pdf

New Roof Construction M A N U A L

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New Roof Construction Manual

Cedar Shake & Shingle Bureau History

This manual is intended for use with Western Red Cedar and Alaskan Yellow Cedar shake and shingle application only. Western Red Cedar and Yellow Cedar products manufactured by CSSB members are labeled with the “Certi” brand name. The species is indicated by either “Yellow” or “Red” Cedar at the top of the label. For ease of reference this

TMmanual refers to “Certi-label Western Cedar” and the term is understood to include both Western Red Cedar and Alaskan Yellow Cedar products manufactured by CSSB members.

Material for this manual has been compiled from various authoritative sources, and many of the construction methods shown herein have been developed by the shake and shingle specialists in both the United States and Canada. The design and application details and methods of construction reflect current good building practice. Other options are possible but ensure that you check with your local code jurisdiction for approval.

The information in this manual is not intended to supercede local building codes.

On June 9, 1915, at a meeting of the Trustees of the West Coast Lumber Manufacturers Association, it was agreed to establish a branch of the association to serve those members who manufactured shingles. Our influence grew, and as we survived both the Great Depression and World War II, manufacturers continued their quality commitment. In 1963 the organization merged with the Handsplit Shake Bureau to become the Red Cedar Shingle & Handsplit Shake Bureau.

Manufacturers’ product lines continued to broaden and, in 1988, the members changed the organization's name to the Cedar Shake & Shingle Bureau. In the late 1980s, mill quality control inspections were subcontracted to independent, third party quality control agencies.

Each year the Cedar Shake & Shingle Bureau’s staff answer thousands of technical questions and product selection queries. Our proud history, quality reputation and dedicated members provide excellent Certi-label™ cedar shake and shingle roofing and siding products.

TMCerti-label Products Cedar shakes and shingles manufactured by members of the Cedar Shake & Shingle Bureau (”CSSB”) are the only products labeled with the ”Certi” brand name.

Certi-label cedar shakes and shingles are made by experienced craftsmen who take pride in their trade and the quality of their product. Despite their varying sizes and sometimes remote locations, member mills are bound together by a rigid quality code.

Unannounced independent inspections conducted by accredited third party agencies ensure that product quality is maintained.

Products are inspected to conform with various local, national and international codes and standards (contact the CSSB for specific details).

Each bundle of product has the mill’s distinctive Certi-label tucked under the bundle strap. Asking for “the blue label” or “number one blue label” is not specific enough: CSSB members' products are the only ones with the Certi brand name on the label.

CSSB

CSSB

Approved Installer Guidelines

Product Warranty

Good workmanship is crucial to the integrity of any roofing system. Installers should read this manual carefully and ensure that they follow proper workmanship practices.

Approved Installers agree to follow the guidelines in this manual, or local code regulations, if stricter than the guidelines contained in this manual.

The administers a product warranty for Certi-label product applications performed by an Approved Installer. Warrantied Certi-label products include ONLY Premium Grade and Number 1 Grade materials.

Note: This manual replaces all previous versions of the "Cedar Shake and Shingle Bureau Design and Application Manual for New Roof Construction.”

INTRODUCTION

CONTENTS

Certi-label Products pages 1-2

General Design & Application Details pages 3-5

Mansard Roof Details page 6

Low Slope Roof Details page 7

Hip & Ridge Details page 7

Roof Juncture Details pages 8-9

Roof Valley Flashing Details pages 9-10

Roof Projection Flashing Details page 11

Roof Fastener Guidelines page 12

Ventilation Details pages 13-14

Specialty Roof Deck Details pages 15-16

Cold Roof System Details pages 17-18

High Humidity Area Details page 19

Coverage & Exposure Tables page 20

Care & Maintenance Overview pages 21-22

Specification Guidelines pages 23-24

How to Read a Certi-label page 25

Cover House Photo:

Architect: Shope Reno Wharton Photo: Robert Benson

Cover Product Photo: John Gordon

CERTI-LABEL PRODUCTS

CERTI-LABEL CEDAR SHAKES

Number 2 Red Label

A good grade for many applications. Not less than 10" clear on 16" shingles, 11" clear on 18" shingles and 16" clear on 24" shingles. Flat grain and limited sapwood are permitted in this grade.

Number 3 Black Label

A utility grade for economy applications and secondary buildings. Not less than 6" clear on 16" and 18" shingles, 10" clear on 24" shingles.

Number 4 Undercoursing

A utility grade for undercoursing of double coursed sidewalls only. Not a roofing material and not to be used as a starter course for roofs.

These shakes are sawn both sides. Premium and Number 1 Grades are the most common. Premium Grade is 100% edge grain, 100% clear and 100% heartwood. Number 1 Grade allows up to 20% flat grain in each bundle.

Number 2 and 3 Grades are also available.

Tapersawn Red Cedar Shakes

CEDAR SHAKE & SHINGLE BUREAU

THE RECOGNIZED AUTHORITY SINCE 1915

SUMAS, WASHINGTON (604) 820-7700

These shakes have split faces and sawn backs. Cedar logs are first cut into desired lengths. Blanks or boards of proper thickness are split and then run diagonally through a bandsaw to produce two tapered shakes from each blank. Available in Premium Grade (100% edge grain) or Number 1 Grade (Up to 20% flat grain allowed in each bundle).

Handsplit Red Cedar Shakes

PREMIUM GRADE

PREMIUM GRADE

CEDAR SHAKE & SHINGLE BUREAU

100% Edge Grain

THE RECOGNIZED AUTHORITY SINCE 1915

SUMAS, WASHINGTON (604) 820-7700

CERTI-SPLIT

Produced by hand, using a sharp bladed steel froe and a mallet. The natural shingle-like taper is achieved by reversing the block, end-for-end, with each split. Premium Grade only. (100% edge grain)Handsplit Red Cedar Shakes

CEDAR SHAKE & SHINGLE BUREAU

PREMIUM GRADE

100% Edge Grain

100% Edge Grain

THE RECOGNIZED AUTHORITY SINCE 1915

SUMAS, WASHINGTON (604) 820-7700

CERTI-SPLIT

Produced by machine or in the same manner as tapersplit shakes except that by splitting from the same end of the block, the shakes acquire the same thickness throughout. Premium Grade only. (100% edge grain)

Certi-Split Straight-Split

Handsplit Red Cedar Shakes

CEDAR SHAKE & SHINGLE BUREAU

THE RECOGNIZED AUTHORITY SINCE 1915

SUMAS, WASHINGTON (604) 820-7700

CERTI-SPLIT

The premium grade of shingles for roofs and sidewalls. These top-grade shingles are 100% heartwood, 100% clear and 100% edge grain. Available in 16" or 18" or 24" lengths.- 100% Edge Grain - 100% All Clear -

- 100% Heartwood -

R IGRADECE T

Red Cedar Shingles

CEDAR SHAKE & SHINGLE BUREAU

THE RECOGNIZED AUTHORITY SINCE 1915

SUMAS, WASHINGTON (604) 820-7700

PREMIUM GRADE

100% Edge Grain

(604) 820-7700

(604) 820-7700

(604) 820-7700

Certi-Split Handsplit Shakes

Certi-Sawn Tapersawn Shakes

Certi-Split Tapersplit

Number 1 Blue Label

CERTIGRADE CEDAR SHINGLES

CERTI-LABEL PRODUCTS

CERTI-GUARD

PRESSURE- FIRE-RETARDANT

CEDAR SHAKE & SHINGLE BUREAU

TREATED SHAKES & SHINGLES

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CERTI-GUARD

PRESSURE- FIRE-RETARDANT

CEDAR SHAKE & SHINGLE BUREAU

TREATED SHAKES & SHINGLES

R Pressure-Impregnated Treated Products

Certi-Guard Fire-Retardant Treated Cedar Shakes and Shingles

Certi-Last Preservative-Treated Cedar Shakes and Shingles

Certi-label products can also be treated. Products are available either fire-retardant-treated OR preservative-treated. Special care must be taken to follow the treatment company’s recommended installation instructions.

Premium and Number 1 Grades of Certi-Split shakes, Certi-Sawn shakes, and Number 1 Grades of Certigrade shingles are available pressure-impregnated with fire retardants. Certi-Guard products may be used for Class A, B and C roof systems. Contact the treatment company for treatment warranty information, accessory product requirements (including recommended fastener types) and application details for treated cedar material. Local code jurisdictions have additional information regarding applications in specific areas.

Premium and Number 1 Grades of Certi-Split shakes, Certi-Sawn shakes, and Number 1 Grades of Certigrade shingles are available preservative-treated by pressure processes. This product is ideal in areas of high humidity. Specify the Certi-Last treating label for this extra protection. Contact the treatment company for treatment warranty information, accessory product requirements (including recommended fastener types) and application details for treated cedar material.

Note: Cedar’s natural color varies as shown in these examples, yet without applying a paint or stain it will all weather to a beautiful gray.

CERTI-LAST

PRESERVATIVE TREATED CEDAR SHAKES & SHINGLES

CEDAR SHAKE & SHINGLE BUREAU

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• Be sure that felt interlay paper on shakes does not extend below a line that is twice the exposure above the butt (i.e. a 24" shake at 10", exposure would have felt applied 20” above the butt).

• Never interlay shingles with felt.

• Keyways must not be aligned and must be a minimum 1 1/2” offset from the course above.

• DO NOT drive nail heads or staple crowns below wood surface.

• Overdriving or underdriving the fasteners can seriously damage the integrity of your roofing system.

Photo: Celia Pearson

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Figure 1: Spaced Sheathing For applications using varied exposures, the center of the sheathing board should be equal to the distance of the exposure.

Figure 3: Spaced Over Solid Combination Sheathing This is the preferred system for shingle application, in areas with high humidity or where additional ventilation is required. When using Certi-Last products, they may be applied directly to the deck.

Rafter

Rafter header Fascia

Gutter

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Spaced sheathing

Eave protection (extend to rake edge)

Certi-label shakes

Solid sheathing

Figure 2: Solid Sheathing

Rafter

Rafter header

Fascia

Gutter

Eave protection (extend to rake edge)

GENERAL DESIGN AND APPLICATION DETAILS

Sheathing

Staggered Butt Applications

Shakes and shingles may be applied over spaced sheathing. Spaced sheathing is usually 1 x 4 or 1 x 6 softwood boards and shall not be less than 1 x 4 boards.

Solid sheathing is recommended for shakes and may be required in seismic regions or under treated shakes and shingles. Solid sheathing is used in areas with wind-driven snow. Please note that the only solid sheet sheathing tested with Certi-label shakes and shingles is plywood. Check with your local building official for plywood thickness/dimensions. Eave protection is used on the edge where 36" felt underlay is used and should extend up at least 24" beyond the exterior wall but it is not meant to cover the entire roof.

Staggered butt applications are made by shortening the exposure less than the greater maximum exposure. No shakes or shingles shall be applied greater than the maximum exposure allowed. Check with local building codes for approval of this installation method.

Note: Do not cover the entire deck with water proofing membrane. This will not allow shingles to breathe. See CSSB technical bulletin “Asphalt-Saturated Organic Felt”

Certi-label shakes

Note: in areas of high humidity, nailing strips or a continuous ventilation product may be used, or Certi-Last treated shakes may be applied directly to the deck.

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Gutter

Certi-label shingles

Eave protection (extend to rake edge)

Solid sheathing

Rafter header

Fascia

Rafter

2 x 4 spacers

1 x 4 or 1 x 6 nailing strips

Solid sheathing at eave

Solid sheathing at eave

Certi-label Shakes A solid deck is recommended in seismic activity, hurricane and tornado regions and in areas where wind-driven snow is encountered. Roofing felt system interlay between the shake courses is required whether the sheathing is spaced or solid. The felt interlay acts as a baffle that prevents wind-driven snow or other foreign material from entering the attic cavity during extreme weather conditions. The felt interlays also increase the roof's insulation value. The felt interlay system forces water to the surface.

If spaced sheathing is used in shake application, the sheathing is usually 1 x 6 boards spaced on centers equal to the weather exposure. (Table 4, Page 20) at which the shakes are to be laid - but never more than 7 ½” for 18” shakes and 10” for 24” shakes on roof installations. When 1 x 4 spaced sheathing is installed at 10” on center, additional 1 x 4 boards must be installed (i.e. maximum allowable spacing is approximately 3 ½” measured from edge to edge between the sheathing boards). Please note that the only solid sheet sheathing tested with Cert-label™ shakes & shingles is plywood. Check with your local building official for plywood thickness/dimensions.

Special care should be taken when installing the felt interlays over spaced sheathing to ensure that an effective baffle is formed (Figure 1). The felt should be applied over the top portion of the shakes and extend on to the spaced sheathing so that the bottom edge of the felt is positioned at a distance above the butt equal to twice the weather exposure.

Certi-label Shake Application Shakes, like shingles, are normally applied in straight, single courses. The following application details (Figure 4) must be observed.

1. The starter course may be one or two layers of cedar shingles or shakes overlaid with the desired shake. A 15" shake is made expressly for starter and finish courses.

2. Butts of first course shakes should project 1 1/2" beyond the fascia and approximately 1" over the gable or rake end.

3. The CSSB recommends using an 18" wide strip of Type 30 ASTM Designation 226 (ASTM D 226) or ASTM Designation 4869 (ASTM D 4869) roofing felt laid over the

Figure 4: Certi-label Shake Application top portion of the shakes and extending on to the sheathing. (Check with your local building official for exact specifications in your area).

The bottom edge of the felt should be positioned above the butt of the shake at a distance equal to twice the weather exposure.

For example, 24" shakes, felt extends up 14" onto the sheathing forcing water to the surface.

4. Spacing between adjacent shakes should be a minimum of 3/8" and a maximum of 5/8”.

5. Shakes shall be laid with a side lap of not less than 1 1/2” between joints in adjacent courses.

Architect: Shope Reno Wharton, Photo: Robert Benson

GENERAL DESIGN AND APPLICATION DETAILS4

Eave protection ( to rake edge)extend

6. Straight-split shakes should be laid with the froe-end (the end from which the shake has been split and which is smoother) towards the ridge.

Notes:

1) See page 19 for high humidity areas.

2) For 3 ply Tapersawn Shake application, please see the CSSB technical bulletin “3 Ply Application”.

Two nails (only) for each shake approximately 3/4" from edge and approximately 1 1/2" above exposure line.

Rafter header Fascia

Gutter

Adjacent course joints should be offset 1 1/2" minimum

Rafter

Product should project 1 1/2" beyond the fascia and approximately 1" over the gable or rake end

Starter course

Exposure

Space shakes 3/8" to 5/8" apart

Plywood sheathing

The bottom edge of the felt should be positioned above the butt of the shake at a distance equal to twice the weather exposure. Never interlay shingles with felt.

Currently the only acceptable solid sheathing product tested for use with Certi-label shakes is plywood.

Figure 5: Certi-label Shingle Application

Figure 5a: Course Alignment

For 4:12 slope and steeper, use Number 1 Grade shingles at 5", 5 1/2" and 7 1/2” exposures for 16", 18" and 24" shingles respectively. For lower roof slopes and lower product grades use reduced exposures (See Page 20)

Centerline of heart

GENERAL DESIGN AND APPLICATION DETAILS

Certi-label Shingles

Certi-label Shingle Application

There are two acceptable methods for application of spaced sheathing: One is to space 1 x 4 boards to coincide with the weather exposure (Table 2, Page 20) of the shingles (Figure 5). Thus, if the shingles are to be laid at 5 1/2" to the weather, the sheathing boards would also be spaced at 5 1/2" on center. In this method of application each shingle is nailed to the center of the 1 x 4 board. With 7 1/2" weather exposures, the center of the sheathing board shall equal the distance of the weather exposure.

Alternatively, although not commonly used, a breather-type underlayment, such as roofing felt, may be applied over either solid or spaced sheathing. Check with your local building official for their preference in your area.

Please note that the only solid sheathing product tested for use with Certi-label shakes and shingles is plywood. Check with your local building official for plywood thickness/dimensions.

Regardless of style, the following basic application details (Figure 5) must be observed.

1. Shingles must be doubled or tripled at all eaves.

2. Butts of first course shingles should project 1 1/2" beyond the fascia and approximately 1" over the gable or rake end.

3.Spacing between adjacent shingles (joints) should be a minimum of 1/4" and a maximum of 3/8".

4. Certi-label shingles shall be laid with a side lap not less than 1 1/2" between joints in adjacent courses, and not more than 10% shall be in direct alignment in alternate courses. Check with your local building official in your area.

5. In lesser grade shingles (Figure 5a) containing both flat and vertical grain, joints should not be aligned with centerline of heart.

6. Flat grain shingles wider than 8" should be split in two before nailing. Knots and similar defects should be treated as the edge of the shingle and the joint in the course above placed 1 1/2" from the edge of the defect.

Architect: Gaylord Grainger, Libby O'Brien-Smith Architects, Photo: Eduardo Calderon

Spaced sheathing should be 1 x 4 or 1 x 6

Rafter header

NEW PIC

Knot or similar defect

1 1/2"

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Fascia

Adjacent course joints should be offset 1 1/2" minimum

Alternate course joints should not align

Gutter

Space shingles 1/4" - 3/8" apart

Two nails (only) for each shingle approximately 3/4" from edge and approximately 1 1/2” above exposure line.

First course doubled or tripled

Solid wood sheathing

Eave protection (extend to rake edge)

Rafter

The mansard is particularly well suited to renovation work on pitched roof houses because the upper story can be enlarged without adding extra height to the structure.

The low downward slope of the mansard roof line acts visually to reduce the scale of a building and helps to eliminate a boxy appearance. This technique is used frequently on large commercial projects, particularly those near residential neighborhoods. It is also a common solution to the problem of avoiding a monotonous appearance on flat-roofed frame apartment buildings.

Properly used, a mansard roof can strengthen the design without substantially increasing construction costs. If raised up above the level of a built-up roof the mansard can screen out roof penetrations or mechanical equipment.

The variety of mansard roofs is practically infinite. One of the most widely used (and misused) roof designs, its proportions and scale are very important and care should be taken to avoid a mansard roof line that is either too skimpy or too generous.

Two of the most widely used roofing materials on the mansard roof are Certi-label cedar shakes and shingles. Cedar shakes, with their heavier texture and solid appearance, are perhaps more frequently specified for mansards although shingles are also used, particularly when a lighter scale is desired.

The light weight and ease of application of Certi-label shakes and shingles contribute substantially to economical construction.

Construction details for typical mansard roofs are shown in Figure 6.

MANSARD ROOF DETAILS

Figure 6: Mansard Roof

Photo: Murray Levin

Eave protection min. 36"

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Certi-label shakes

Two nails (only) for each shake approximately 3/4" from edge and approximately 1 1/2" above exposure line.

Plywood Sheathing

The bottom edge of the felt should be positioned above the butt of the shake at a distance equal to twice the weather exposure.

Never interlay shingles with felt.

Space shakes 3/8" to 5/8" apart

Figure 8: Certi-label Hip and Ridge Application

Figure 7: Certi-label Shake Application to Low Slope Roofs

The minimum roof slope on which Certi-label shakes are recommended is 4:12 and for Certi-label shingles, 3:12. It is possible, however, to apply Certi-label shakes or shingles successfully to solid sheathed roofs of lower slope providing a special method of application is followed (Figure 7). The prescribed method provides a double roof on which the Certi-label shakes or shingles are applied to a lattice-like framework embedded in a bituminous surface coating.

A hot mop or similar approved membrane should be applied over the roof deck. Consult your local building official for approved products in your area. With the final hot-mop application 2 x 4 spacers of Western Red Cedar or preservative treated lumber are embedded in the bituminous coating. These spacers are installed over the rafters and extend from eave to ridge. Check with your local building official for their preference in your area.

Next, 1 x 4 or 1 x 6 nailing strips, spaced according to the weather exposure selected for the Certi-label shakes or shingles, should be nailed across the spacers to form a lattice-like nailing base. For example, if 24" shakes are to be installed at a weather exposure of 10", the nailing strips would also be spaced at 10" on centers. When 1 x 4 spaced sheathing is installed at 10" on center, additional 1 x 4 boards must be installed.

Finally, the Certi-label shakes or shingles are applied in the normal manner with a starter course at the eave and felt interlay between each course of shakes (Figure 7).

Intersecting roof surfaces at hips and ridges should be capped to ensure a weather-tight joint. Site-made or factory-assembled hip and ridge units may be used, but both types must have alternate overlaps and concealed nailing (Figure 8). When ridge cap and field product are the same length and grade, the weather exposure of the ridge cap should be the same exposure as the field product of the roof.

Nails must be longer than those used on the field of the roof and of sufficient length to penetrate 3/4" into or completely through the sheathing. Install a strip of felt, eave protection material or metal over hip or ridge under the ridge or hip cap. If longer or shorter ridge cap is used, adjust exposure accordingly.

Certi-label Hip And Ridge Details

LOW SLOPE ROOF DETAILS, HIP AND RIDGE DETAILS 7

24" Certi-label shakes at 10" exposure

18" felt interlay

2 nails per shake

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

2 x 4 spacers

4" overlap of felt 1 x 4 or 1 x 6 nailing strips

Solid sheathing

Hot mop or similar approved membrane.

Consult your local building official for approved products in your area.

Shake starter course

36" felt underlay

Rafter Rafter header

Fascia

Gutter

Solid sheathing at eave

Double starter course

Notch first piece of starter course

Choose material of uniform width between 4" and 5" (if making units with field material)

Notched

Alternate overlap

Cut back edge of shingles or shakes on a bevel

Join ridge material with type 304 or 316 stainless steel fasteners

See page 12 for fastener details.

Figure 9: Convex Roof Juncture

Double or triple starter course

Metal flashing

Sheathing

Correct construction of roof junctures and slope transitions is vital to ensure the integrity of the roof system. In the following cases, where metal flashing is employed, it should be no less than 26 gauge galvanized steel or acceptable equivalent. Check with your local building official for their preference in your area. It should be painted on both sides with a good metal or bituminous paint. Flashing materials should be painted after bending to maintain the integrity of the coating.

On this type of juncture (Figure 9) metal flashings should be installed to cover the top 4" of the wall and the bottom 8" of the roof slope before the final course of Certi-label shakes or shingles is nailed to the top of the wall. A strip of wood molding can be applied after final wall course is installed. A double or triple starter course is then applied at the eave, with a 1 1/2" overhang over the outside wall trim. The roof can then be completed in the normal manner.

Metal flashings for the concave juncture are similar to those for the convex type. They should be installed to cover the top of the roof slope and the bottom 4" of the wall before the final course of Certi-label shakes or shingles is installed. The final roof course should be installed so that the tips fit as snugly as possible against the wall at the juncture. A double starter course should be applied at the start of the wall surface and the remaining wall courses applied in the recommended manner. If nails are not acceptable through exposed metal, metal clips can be used to hold down the flashing.

Roof transitions (Figure 10) require appropriate flashing, felt and product application. Changes in roof slope should be detailed in a similar manner as concave junctures, to ensure the integrity of the roof system. Solid sheathing is required above and below the change in slope, metal flashing is required across the change in slope, and a 36" strip of starter felt is required on the upper slope, installed in the same fashion as at the eaves.

Convex Juncture

Concave Juncture

Roof Transitions

ROOF JUNCTURE DETAILS

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Wood molding

Metal flashing 6" up - 6" below

Solid sheathing

Interwoven felt for shakes only

36" starter felt

Product should project 1 1/2 beyond the fascia and approximately 1" over the gable or rake end

Double starter course

Steeper slope roof

Lower slope roof

Courtesy: Western Wood Products, Photo: John Spaulding

Figure 10 Low Slope to Steep Slope Roof Transition Detail - Certi-label shakes

(Certigrade shingle application is similar but without felt interlay)

Figure 1 12 Swept or Bell Eave1: Apex Roof Juncture Figure

For excessive sweep shingles may be steam bent

Last course over flashing

Ridge cap

Apex Juncture

Swept or Bell Eave

On this roof juncture (Figure 11) metal flashing should cover the top 8" of the roof and the top 4" of the wall. It should be installed before the final course of Certi-label shakes or shingles is applied to the wall. The recommended sequence of application is to apply Certi-label shakes or shingles first to the wall then to the roof. The overhanging roof material is then trimmed flush with the wall.

Finally, specially prepared ridge units are applied over the wall-roof juncture so that in each matching pair the roof piece overlaps the wall piece each time.

When Certi-label shakes or shingles are to be applied to a swept or bell eave where the curvature is excessive, it may be necessary to soak them for a period (usually overnight) or steam them prior to installation. A double starter course is employed in the usual manner. Exposure is determined by the slope of the roof and the type of Certi-label shake or shingle selected. At lower pitches waterproof eave protection should be used.

ROOF JUNCTURE DETAILS

Double eave protection

Sheathing

Metal flashing

Roof Valley Flashing Detail

Most roof leaks can occur where water is channelled off the roof or where the roof abuts a vertical wall or chimney. At these points, metal valleys and flashings are used to assist the Certi-label shakes and shingles in keeping the structure sound and dry.

Structural members that join a roof should also be flashed at all intersecting angles to prevent leakage. Step flashing should extend under the Certi-label shakes and shingles, up the vertical surface, (one flashing installed on each course concealed under the covering course) and should be covered by a second layer of flashing (counter-flashing).

Flashing should be pre-painted both sides using a good metal or bituminous paint (Figure 13a). Flashing strips which must be bent to sharp angles should be painted after bending. Metal flashing with baked-on enamel coating is available in some areas.

Different flashing metals are available in different areas depending on climatic variations. It is good practice to use metals that have proven their reliability under the specific conditions to be encountered. It is important that metal flashing have the same longevity as Western Red Cedar. Check with your local building official for their preference in your area.

Note: For unusual roof applications contact the Cedar Shake & Shingle Bureau for a list of members who can assist you with specific questions.

Open valley width 4" to 8" depending on water volume.

Mark anticipated water lines (width of open valley) on valley sides with a chalk line.

Use minimum nails to hold metal in place

Roofing felt

Valley metal 8'0" long overlapped 6" at joints/ painted both sides

Eave protection (extend to rake edge)

Metal to extend as far as shakes or shingles

Figure 13a: Valley Metal

W valley metal

Solid sheathing at eave

Eave felt should be lapped over the valley joint to give 3 levels of eave protection.

(valley felt, eave felt and metal)

ROOF VALLEY FLAS SHING DETAIL

Valley felt

W valley metal 1/2" crimp

2 33

Figures 13a-13d: Flashing Details for Shake and Shingle Valleys

Figure 13c: Valley Product Application

Figure 13d:

Roof Valley Flashing Detail

For roofs with slopes of 12:12 or greater, valley flashing should extend not less than 8" on each side of the valley centerline. For roof slopes less than 12:12, flashing should extend not less than 11” each side. Valley flashing should be center-crimped, painted, galvanized steel or aluminum. Valley metal should be underlayed with minimum Type 30 ASTM Designation 226 (ASTM D 226) or ASTM Designation 4869 (ASTM D 4869) roofing felt. Shingles should not be applied with their grain parallel to the valley centerline and those extending into the valley should be cut at the correct angle (Figure 13b).

On shake roofs it is recommended that a strip of Type 30 ASTM Designation 226 (ASTM D

226) or ASTM Designation 4869 (ASTM D 4869) roofing felt be installed over the sheathing and under the metal valley. Metal valleys should be center-crimped, painted, galvanized steel or aluminum and should extend not less than 11" on each side of the valley centerline. In some areas, however, flashing width requirements may differ and local building codes should be consulted.

Shakes should not be applied with their grain parallel to the valley centerline and those extending into the valley should be cut at the correct angle (Figure 13c).

Valleys: Certi-label Shingles

Valleys: Certi-label Shakes

ROOF VALLEY FLASHING DETAILS10

Figure 13b: Typical Saddle Flashing Detail

36" valley felt (left side)

36" valley felt (right side)

1/2" folded back trim

W valley metal

W valley metal lapped at ridge (2" lap)

Order of applying Certi-label shakes or shingles at valley:

1. Stop course line here

2. Place pre-cut valley piece so that cut-angle is positioned on the valley guide chalk line with tip on the course line.

3. Select product of the required width to complete the course of Certi-label shakes or shingles.

Keep nails well away from the center of valley

Hidden felt

Courtesy: Western Wood Products, Photo: John Spaulding

Figures 14a-14e: Flashing Details for Typical Roof Projections

Figure 14a: Skylight Flashing Figure 14b: Skylight Installation

ROOF PROJECTION FLASHING DETAILS

Figure 14d: Typical Projection Flashing

Figure 14c: Typical Projection Flashing

Figure 14e: Typical Projection Flashing

1" minimum clearance around projection

Keep edge of flange minimum 2" from edge of Certi-label shake or shingle joint Counter flashing

Jack Plumbing stack

Certi-label shake or shingle joint

Nails should not penetrate flashing flange underneath

Step flashing 3" laps

Bottom apron flashing

Top, head, saddle, pan or cricket flashing

Bottom or Apron flashing

Head flashing

Step flashing interwoven with each course

Typical chimney flashing requiring soldering

Caulking

Certi-label product

Certi-label product

Step flashing 3" minimum overlap

Horizontal width 4" 2 1/2"

3" 2 1/2"

Shakes Shingles

Recommended step flashing width

Typical chimney flashing not requiring soldering

Solder joints

3" 6"

3" minimum

Caulking

6" minimum

Vertical width

Bottom apron flashing

Counter flashing

ROOF FASTENER GUIDELINES

YES

Correct - flush with surface

NO

Underdriven

NO

Overdriven

Type of Certi-label Nail Type and Shake or Shingle Minimum Length

Certi-Split & Certi-Sawn Shakes Type (in)

18" Straight-Split 5d Box 1 3/4

18" and 24" Handsplit and Resawn 6d Box 2

24" Tapersplit 5d Box 1 3/4

18" and 24" Tapersawn 6d Box 2

Certigrade Shingles Type (in)

16" and 18" Shingles 3d Box 1 1/4

24" Shingles 4d Box 1 1/2

Fasteners

The CSSB does not recommend the use of electro galvanized (EG) fasteners.

Note: Longer fasteners of the same quality may be required for nailing ridge product

Nails

Staples

Each Certi-label shake or shingle shall be applied with two fasteners. Nails must be stainless steel-type 316 in locations within fifteen (15) miles of salt water (Ref. Stainless Steel Industry of North America-Washington, D.C., www.ssina.com). For locations outside the salt water zone - nails must be Type 304 or 316 stainless steel, or hot-dipped zinc coated galvanized conforming to minimum

2standard ASTM A 153 Class D (1.0 oz/ft ) or better. Stainless steel nails, although more expensive, offer the highest degree of corrosion resistance. Some nail manufacturers offer nails specifically for wood shake or shingle roof application. Contact the nail manufacturer for further information to ensure the nail used is correct for your application.

If you choose to use staples they must be stainless steel Type 316 in locations within fifteen (15) miles of salt water. (Ref. Stainless Steel Industry of North America-Washington, D.C., www.ssina.com). For locations outside of the salt water zone - stainless steel staples type 304 or 316 must be used. Each Certi-label shake or shingle shall be applied with two (2) staples. Staples must be 16 gauge with crowns 7/16'' minimum horizontal, maximum 3/4”' horizontal to the Certi-label shake or shingle butt.

Location/Penetration Fasteners, two (2) per shake or shingle, shall be applied approximately 3/4” from the edge and approximately 1 1/2'' above the exposure line. Fasteners shall be long enough to penetrate into the solid wood sheathing at least 3/4” or all the way through. Minimum nail lengths are shown in the fastener chart below. Nails and staples must be driven flush with the surface of the Certi-label shake or shingle. Overdriving the fastener can split and/or distort the Certi-label shake or shingle.

Important Notes:

Overdriving or underdriving any fastener will affect the integrity of the roofing system. Fasteners utilized must be specific for use with wood shakes and shingles to prevent splitting and other weakening factors.

Pressure Impregnated Treated Shakes and Shingles Specification of fasteners to be used with fire-retardant-treated (Certi-Guard) and preservative-treated (Certi-Last) shakes or shingles must be obtained from the treatment company. Some types of fasteners may not be compatible with treated material.

The information above is not intended to supersede local building codes.

Air flow Insulation

Figure 15c: Shed Roof

Figures 15a-15c: Ventilation Details

Certi-label shakes or shingles (applied per specification)

Roof rafter

Air flow

1-2" diameter screened vents each roof rafter space

Figure 15a: Gable Roof With Attic

Figure 15b: Cathedral Ceiling With Partial Attic

The importance of good attic ventilation beneath the roof cannot be overemphasized. Such movement of air will prevent or inhibit condensation of moisture on the undersurface of the Certi-label shakes or shingles, or on the roof decks. Vents should be provided at the soffits (eaves) as well as at gable ends (screened to prevent ingress of insects), on roof by using attic roof ventilation or preferably the ridge lines with cross-ventilation desirable. A rule of thumb for adequate ventilation is that the ratio of total net free ventilation area to the area of the attic should be not less than 1:150, with compensation made for screens over vent apertures. In the case of a balanced system a 1 square foot per 300 square feet of floor area may be adequate ventilation.

Check with your local building department. Attic fans may be beneficial by supplying additional movement of air in attic spaces. Several roof ventilation construction techniques are shown in Figures 15a-15c.

Any modification to the vapor barrier system or addition of a vapor barrier system should only be done after consulting with your local building official or a building envelope specialist. In some areas, building envelope specialists are regulated by government. Please check with local building officials to see if there are professional requirements in your area.

Ventilation Guidelines

VENTILATION DETAILS

Continuous screened vent

Louvered vent at each end of attic

Insulation

Air flow

Roof rafter or truss

Certi-label shakes or shingles (applied per specification)

Air flow

Certi-label shakes or shingles (applied per specification)

Air flow

Roof rafter

Louvered vent at each end of attic

Insulation

Continuous screened vent

Ridge ventilation product

Ridge ventilation product

Figure 16: Ridge Ventilation Detail

Airflow through ridge

Caulking

Roofing felt

Certi-Ridge shake or shingle ridge

Ridge ventilation product installed to manufacturer’s specifications

Felt folded back

Ridge Vents

Low Slope (6:12 or less)

Steep Slope (8:12 or greater)

Severe Climate Areas

The amount of venting depends upon the size of the roof, roof design/structure, (attic present or not, etc.) as well as local climatic conditions.

Check with your local building official for requirements in your area. One rule of thumb for venting the attic area is 1 square foot per 150 square feet of floor area. One half of this (1/2 square foot per 75 square feet of floor area) amount should be in the soffit or eave and one half (75 square feet) in the roof system. In the case of a balanced system 1 square foot per 300 square feet of floor area may be adequate ventilation. Check with your local building official.

The CSSB recommends the installation of ridge ventilation product that allows for installation of pre-manufactured ridge applied over the vent material. There are many manufacturers of this design.

On steep slope roofs, the correct ridge ventilation products can actually facilitate the ease of installation of Certi-label ridge units.

Always follow the manufacturer's installation instructions. The predominant ridge material manufactured today is for a low slope roof.

However, by using a ridge ventilation product that is malleable and at least 8 1/2“ wide, the material can be installed across the minimum 3” of air space at the ridge to create a shallowing of the slope at the ridge. Care must be taken to caulk the ridge ventilation material to the Certi-label shakes or shingles. Proper nailing of the ridge units will create a serviceable application.

In all wind driven snow areas, the proper ridge ventilation product should have a screening effect to prevent snow infiltration (not louvered or baffled).

VENTILATION DETAILS

Architect: Gaylord Granger, Libby O’ Brien-Smith Architects, Photo: Eduardo Calderon

Figure 17: Specialty Roof Deck-Strapping Over Insulation

Figure 18: Specialty Roof Deck-Vented Roof

Wood decks form an ideal base over which to apply Certi-label shakes or shingles, since they can be attached in the conventional manner.

Rigid insulation raises the issue of how to fasten Certi-label shakes or shingles. The use of abnormally long nails driven through the Certigrade shingles, the insulation and into the deck below is generally unsatisfactory.

Horizontal strapping will be required to overcome the fastening difficulties (Figure 17).

When strapping is used, fewer nails penetrate through the insulation to the deck, and greater thermal efficiency is achieved by reducing the number of conductors. In addition, the lengths of the nails may be chosen to prevent the points from protruding through the deck where they may mar the inside face.

If ice-damming is a potential problem or if reverse condensation is likely to occur, such as may be encountered in an ice arena, a cold roof system should be used in conjunction with horizontal strapping, and ventilation must be provided at the eaves and at the peak. In buildings such as ski cabins that may be subjected to heavy snow loads, it is usually necessary to fasten wood members (typically 2 x 4 on edge) from ridge to eave on the roof deck and place the rigid insulation between.

Strapping is then applied across the top of these members, giving a ventilated air space and avoiding compression of insulation (Figure 18). For additional details on cold roof systems please see page 17.

The need for strapping can often be completely eliminated by the use of a false plywood deck, immediately over the insulation, to which the Certi-label shakes or shingles are directly fastened (Figure 19).

Exterior-grade sheathing panels are ideal for this purpose, since they provide a strong, smooth surface. However, under certain conditions of slope and loading, there may be a tendency for the entire roof above the decking to creep downwards, bending the nail fastenings and compressing the insulation, thereby reducing its efficiency. In such cases, it is often desirable to install the vertical members as previously described.

Wood Deck

SPECIALTY ROOF DECK DETAILS

Rigid insulation

Wooden deck

Certi-label shakes or shingles (applied per specification) Boards

Joist

Nails If the Certi-label shakes or shingles are nailed directly through rigid insulation, a number of problems may be encountered. For instance, the longer nails have thicker shanks which tend to split the Certi-label shakes or shingles.

Product movement may cause a reduction in insulation efficiency. For this reason, the use of strapping or a false plywood deck is again recommended.

Vertical lumber member Rigid insulation

Certi-label shakes or shingles (applied as per specification) Boards

Wooden deck

Joist

Air space

Figure 19: Specialty Roof Deck-Panels Over Insulation

SPECIALTY ROOF DECK DETAILS

Rigid Insulation Numerous types of rigid insulation are now in use, and may be made from expanded polystyrene beads, rigid urethane laminate, low density fiberboard, or from fast-setting liquids poured on-site. They vary in thickness up to more than 2" and in length and width depending upon the manufacturer. All these types are efficient insulators and are usually of sufficient density to hold the weight of a normal roofing material without the need for lumber bridging. If you live in an area where snowfall is prevalent, please consult your local building official for snow load requirements.

Exterior panels Rigid insulation

Wooden deck

Certi-label shakes or shingles (applied per specification)

Joist

For more technical information please contact our office at

Tel: (604) 820-7700

Fax: (604) 820-0266 info@cedarbureau.com www.cedarbureau.org

If shingles are applied over insulation and ventilation is required, nailing strips may be applied under shingles (see figure 23b on page

®19) For areas of high humidity Certi-Last preservative treated product is recommended.

Brindisi and Yaroscak Custom Builders, Inc. Architect: George Dumitru

Figures 20 & 21: Cold Roof Systems

Figure 20: Gable Roof

Figure 21: Shed Roof

Double starter course

Screen Rigid insulation

Decking

Vented space

Vented space

Certi-label shakes and shingles are an excellent roofing material for cold weather areas that experience heavy snowfall and severe temperature extremes. Certi-label shakes and shingles offer the advantages of durability, superior wind resistance and good thermal and acoustical properties. As with any other roofing material, however, their best performance depends upon proper design, sound construction practice and correct installation.

In cold weather areas and particularly in mountain regions that experience very heavy snowfall, the cold roof - or vented roof system - is recommended (Figures 20 & 21).

The principle of this system is to allow a constant flow of cold air above the insulation but below the roofing material. With other roofing systems, ice buildup along the eaves can be a problem. Heat escapes from the insulation and melts snow, which runs down the roof to the cold overhangs where it freezes, causing water to back up and sometimes penetrate the roof systems. A properly installed, vented cold roof eliminates this problem. Venting space should be sufficient to allow a free flow of air from eave to ridge.

There are a number of important considerations that influence roof performance in areas of heavy snowfall, particularly mountain regions.

Design, of course, is very important. The steeper the roof the better the performance.

Chimneys should be located at the ridge or gable ends away from possible snow pressure on the slopes. Plumbing pipes should be located on inside walls and should be extended between the rafters and vented at the ridge. If this is not practical then plumbing vent pipes should be galvanized iron, well anchored inside the roof. (Plastic vent pipes extending through the roof may be dislodged by sliding snow.)

COLD ROOF SYSTEM DETAILS

Certi-label shakes or shingles (applied per specification)

Certi-label shakes or shingles (applied per specification)

Ridge vent

Cap

Screen

Trim Spaced sheathing

Rafter

Insulation

Architect: 3D Building, Photo: David Reeves Studio, Inc.

Figure 22: Half Monitor Roof

Vented space

Screen

Insulation

Certi-label shakes or shingles (applied per specification)

Interior finish

COLD ROOF SYSTEM DETAILS

Wide overhangs at the eaves should be avoided as they provide large cold areas for snow and ice build-up. A strip of metal along the eaves helps shed ice quickly. Sliding ice and snow are constant hazards and should be given primary consideration in the total building design.

Outside doors should not be located at the bottom of a roof slope. Entrances and all pedestrian traffic areas are better situated beneath the gable ends of the roof.

Care must be taken in applying the sheathing boards to facilitate proper nailing. Shake or shingle side lap should be increased to 2". The entire roof must be laid with the same precautions as those taken for any other type of wood shake or shingle roof, with eave protection and an interlay felt between shakes.

Care in cold roof design and installation will result in a sound roof system giving many years of service during severe extremes of winter temperatures and snowfall.

Screen

Courtesy Goat Lake Forest Products Ltd. Photo: Kristy McKamey

SOLID DECK APPLICATION/HIGH HUMIDITY AREA DETAILS 19

Figure 23b: Vertical Strips Over Solid Sheathing Application (Option 2 Depicted)

Figure 23c: Continuous Ventilation Product (Option 4 Depicted)

Figures 23a - 23c: High Humidity Area Details

In areas of high humidity where solid sheathing is required:

Following are 4 different suggested methods of application to increase longevity:

1. Apply Certi-Last pressure-impregnated treated shakes or shingles directly to the sheathing. (Figure 23a)

2. Apply vertical strips over the sheathing in alignment with the rafters below, then place horizontal furring strips on top of the vertical boards. (See Figure 23b).

3. Apply horizontal furring strips to the deck, spaced at the exposure of the product.

4. A continuous ventilation product may be used beneath the Certi-label roofing material (See Figure 23c).

Note: Good ventilation is essential.

Ridge and soffit vents are recommended.

4" overlap of felt Continuous ventilation product

24" Certi-label shakes at 10" exposure

18" felt interlay

2 nails per shake 1 x 4 or 1 x 6 nailing strips

4" overlap of felt 2 x 4 spacers

Solid sheathing

Solid sheathing at eave

Shake starter course

36" felt underlay (extend to rake edge)

24" Certi-label shakes at 10" exposure

18" felt interlay

2 nails per shake

Solid sheathing Shake starter course

36" felt underlay (extend to rake edge)

Two nails (only) for each shake approximately 3/4" from edge and approximately 1 1/2" above exposure line.

Rafter header Fascia

Gutter

Adjacent course joints should be offset 1 1/2" minimum

Rafter

Product should project 1 1/2" beyond the fascia and approximately 1" over the gable or rake end

Eave protection (extend to rake edge)

Starter course

Exposure

Space shakes 3/8" to 5/8" apart

Plywood sheathing

The bottom edge of the felt should be positioned above the butt of the shake at a distance equal to twice the weather exposure. Never interlay shingles with felt.

®Figure 23a: Certi-Last shake application (Option 1 depicted)

Note: The above figures are depicting a shake application - Do not interlay shingles with felt.

Formula for calculating material at reduced exposures:

Square footage divided by reduced coverage = total material required e.g. you are estimating a roof that measures 3200 square feet (32 squares). You have decided to put 16" Certigrade shingles (No.1 Blue Label or No.2 Red Label) at 4" exposure.

The above coverage table (Table 1) tells you that a

4-bundle square at 4" exposure covers 80 square feet.

3200 divided by 80 = 40 squares of material

Maximum exposure recommended for roofs

SLOPE LENGTH

18" 24"

4:12 and steeper 7 1/2" 10" (a)

(a) 24" x 3/8" handsplit shakes limited to 7 1/2" maximum weather exposure per UBC and IBC.

(a) 5 bundIes will cover 100 sq. ft, roof area when used as starter-finish course at 10" weather exposure; 7 bundles…