Attachment_6_-_Roof_Manual_2020_0003.pdf

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2020 Edition

New Roof Construction M A N U A L

UPDATED

EDITION

Cover House Photos:

Top: Courtesy: Robert A. Cardello Architects. Photo Courtesy: Dennis Carbo Photography Bottom left: Courtesy of BCI Bottom right: Photo Courtesy: Tony Bonura

New Roof Construction Manual 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 Cedar Shake & Shingle Bureau® (”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 manual 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 building code official for approval.

Certi-label® Products Cedar shakes and shingles manufactured by Cedar Shake & Shingle Bureau® (”CSSB”) members 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.

INTRODUCTION

High Humidity Area Details pages 20-21

Roof Valley Flashing Details page 11

Specialty Roof Deck Details pages 17-18

CONTENTS

Low Slope Roof Details page 7

Certi-label® Products pages 1-2

Mansard Roof Details page 6

Roof Juncture Details pages 9-10

Care & Maintenance Overview pages 22-23

Cold Roof System Details pages 18-19

Coverage & Exposure Tables page 24

Roof Fastener Guidelines pages 13-14

Ventilation Details pages 15-16

Hip & Ridge Details page 8

Roof Projection Flashing Details page 12

How to Read a page 27 Certi-label®

CSSB History pages 28

Specification Guidelines pages 25-26

General Design & Application Details pages 3-5

Note:

• ONLY experienced professionals who follow proper safety and workmanship practices should implement the information contained herein.

• Different climates have different code requirements. Ensure the right products and installation methods are used per the building code official in your area.

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

• Confirm labels required for warranty registration BEFORE purchasing product.

Ensure warranty registration details are listed on purchase order.

• Refer to www.cedarbureau.org for project inspiration and photo portfolio.

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

Check with building code official for local jurisdiction requirements

This manual presents best practices developed over more than a century of Cedar Shake and Shingle Bureau® (“CSSB”) history. Please contact CSSB technical staff with Certi-label® product or installation questions. The contents of this manual are not intended to supersede local jurisdiction requirements or building code. ALWAYS check with your local code jurisdiction for approval of any installation modifications, including accessory building materials.

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

Certi-Sawn Tapersawn ®

Certi-Split Tapersplit®

Number 1 Blue Label®

CERTIGRADE® CEDAR SHINGLES

Check with building code official for local jurisdiction requirements

CERTI-L ® PRODUCTSABEL

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

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CERTI-LAST

PRESERVATIVE TREATED CEDAR SHAKES & SHINGLES

CEDAR SHAKE & SHINGLE BUREAU

R

T I P S

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

• Once Western Cedar shingles and shakes are pressure-impregnated treated you must contact the treatment company to determine if a finish, such as paint or stain or cleaning solution/agent, is allowable.

Note:

• Confirm product labels required for warranty registration BEFORE purchasing product. Ensure warranty registration details are listed on purchase order.

• Never interlay shingles with felt.

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

• 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).

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

Check with building code official for local jurisdiction requirements

Certi-Guard® Fire-Retardant 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.

Certi-Last® Preservative-Treated Cedar Shakes and Shingles 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-impregnation process. 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.

Pressure-Impregnated Treated Products

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.

Note:

• Always use a permeable underlayment. There is no performance data available for cedar shake and shingle products over synthetic underlayment (over 80 different synthetic underlayments exist). If you elect to use a synthetic underlayment, and have local building code official approval, be sure that it is permeable and resistant to clogging from fine particles, dust and resins.

• Recommended felt types are No. 30 ASTM D226 Type II or No. 30 ASTM D4869 Type IV roofing felt. It is important that felts are asphalt-saturated - certain code approvals can be misleading regarding felt content, so check with your supplier.

• Different climates have different code requirements. Ensure the right products and installation methods are used per the building code official in your area.

• Type of fastener used is critically important. DO NOT use electrogalvanized fasteners. Ring shank nails are used for better withdrawal resistance and in designated high wind zone areas.

Read this manual for further details.

• Confirm product labels required for warranty registration BEFORE purchasing product.

Ensure warranty registration details are listed on purchase order.

• Once Western Cedar shakes and shingles are pressure-impregnated treated you must contact the treatment company to determine if a finish, such as paint or stain or cleaning solution/agent, is allowable.

Figure 1: Spaced Sheathing

Figure 3: Spaced Over Solid Combination Sheathing

Rafter

Rafter header

Fascia

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

Product should project 1 1/2 beyond the fascia and

Spaced sheathing

Felt interlay

Eave protection (extend to rake edge)

Certi-label shakes®

Solid sheathing

Figure 2: Solid Sheathing

Rafter

Rafter header

Rafter header

Fascia

Eave protection (extend to rake edge)

GENERAL DESIGN AND APPLICATION DETAILS

Certi-label shakes®

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

Fascia

Rafter

2 x 4 spacers

1 x 4 or 1 x 6 nailing strips

Solid sheathing at eave

Solid sheathing at eave

Gutter

Gutter

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.

Rafter fascia

Rafter fascia

Felt interlay

This is the preferred system for shake and 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. Note: Figure 3 shows shingle application, shakes require felt interlay.

For applications using varied exposures, the center of the sheathing board should be equal to the distance of the exposure.

Check with building code official for local jurisdiction requirements

Solid sheathing is recommended for shakes and may be required in seismic regions or beneath 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 24" beyond the exterior wall but it is not meant to cover the entire roof.

Sheathing 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.

Recommended felt types are No. 30 ASTM D226 Type II or No. 30 ASTM D4869 Type IV roofing felt. It is important that felts are asphalt-saturated - certain code approvals can be misleading regarding felt content, so check with your supplier.

Staggered Butt Applications 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 non-permeable barrier (including non-permeable underlayment). See CSSB technical bulletin “Asphalt-Saturated Organic Felt”.

The CSSB recommends installing over plywood panel or dimensional lumber sheathing. If other sheathing materials are approved for use by your local building code official, the holding power of the fasteners should also be considered carefully. Contact local building code official for substrate (plywood) attachment fastener detail.

GENERAL DESIGN AND APPLICATION DETAILS

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, 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 1/2" measured from edge to edge between the sheathing boards). Please note that the only solid sheet sheathing tested with Certi-label® shakes & shingles is plywood.

Check with your local building official for plywood thickness/dimensions.

Certi-label® Shakes

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.

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

3. The CSSB recommends using an 18" wide strip of No. 30 ASTM D226 Type II or No. 30 ASTM D4869 Type IV roofing felt laid over the top portion of shakes and extending on to the sheathing. (Check with your local building code official for exact specifications in your area). The bottom

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.

Certi-label® Shake Application

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

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

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.

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

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.

Figure 4: Certi-label® Shake Application

Starter course

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

Rafter header Fascia

Gutter Rafter

Exposure

Plywood sheathing

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

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.

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

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

Eave protection (extend to rake edge)

• See pages 20-21 for high humidity area details

Notes:

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

Rafter fascia

Figure 5: Certi-label® Shingle Application

Figure 5a: Course Alignment

Centerline of heart

GENERAL DESIGN AND APPLICATION DETAILS

Knot or similar defect

1 1/2"

Certi-label® Shingles

Alternatively, although not commonly used, a permeable underlayment (i.e. breathable), such as roofing felt, may be applied over either solid or spaced sheathing.

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 24) 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.

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

Note: The only solid sheathing product tested for use with Certi-label® shakes and shingles is plywood. Check with your local building code official for plywood thickness/dimensions.

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

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

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

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 code official in your area.

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

Certi-label® Shingle Application

Rafter header

Fascia

Rafter fascia

Gutter

First course doubled or tripled

Solid wood sheathing

Eave protection (extend to rake edge)

Rafter

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.

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

Spaced sheathing should be 1 x 4 or 1 x 6

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

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

Alternate course joints should not align

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

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.

MANSARD ROOF DETAILS

Figure 6: Mansard Roof

Photo: Murray Levin

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 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.

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

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.

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 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.

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

Eave protection min. 36"

Certi-label shakes® Plywood Sheathing

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

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

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

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

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

LOW SLOPE ROOF DETAILS7

Rafter

Fascia

1 x 4 or 1 x 6 nailing strips

24" Certi-label® shakes at 10" exposure

18" felt interlay

2 nails per shake

2 x 4 spacers4" overlap of felt

Solid sheathing

Shake starter course

36" felt underlay

Rafter header

Gutter

Solid sheathing at eave

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

Hot mop or similar approved membrane.

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

Check with building code official for local jurisdiction requirements

• When utilizing a non-permeable barrier (including non-permeable underlayment) over the entire roof deck/sheathing system, consult a Building Envelope Specialist.

Note:

• If installing shakes < 4:12 slope or shingles < 3:12 slope, check with your local building code official for approval to make sure the application complies with jurisdictional requirements.

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).

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 to solid sheathed roofs of low slope between 3:12 and 4:12. Certi-Last® pressure-impregnated preservative-treated shakes or shingles are recommended in low slope installations. Shingles must be applied at a reduced exposure. Never interlay shingles with felt. 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.

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.

A hot mop or similar approved membrane should be applied over the roof deck. Consult your local building code 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 code official for their preference in your area.

Figure 8: Certi-label® Hip and Ridge Application

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. Position fasteners approximately 2” above exposure line. 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

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

Position fasteners approximately 2” above exposure line

8HIP AND RIDGE DETAILS

T I P S

Join ridge material with type 304 or 316 stainless steel fasteners See fastener details in this manual.

Cut back edge of shingle or shakes on bevel.

Check with building code official for local jurisdiction requirements

• Face nailing is not aesthetically pleasing nor is it good for the roof system integrity.

Note:

• Ensure ridge is properly ventilated to comply with local building code requirements (check this manual for more details).

• If making hip and ridge in the field, check warranty paperwork submission requirements.

• 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.

Figure 9: Convex Roof Juncture

Double or triple starter course

Metal flashing

Sheathing

Roof Transitions

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, check with your local building code official for minimum gauge/thickness requirement. 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.

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.

Concave Juncture

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.

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.

Convex Juncture

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)

ROOF JUNCTURE DETAILS9

Figure 11: Apex Roof Juncture

ROOF JUNCTURE DETAILS

Double eave protection

Roofing felt

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

ROOF VALLEY FLAS SHING DETAIL

Valley felt

Last course over flashing

Ridge cap

Sheathing

Metal 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.

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).

Roof Valley Flashing Detail

Swept or Bell Eave 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.

Figure 12: Swept or Bell Eave

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 code official for their preference in your area. When using a pressure-impregnated treated product, contact the treatment company for metal specifications.

Eave felt should be lapped over the valley joint to give 3 levels of eave protection. (valley felt, eave felt and metal)

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

Use minimum nails to hold metal in place

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.

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

Apex Juncture 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.

For excessive sweep shingles may be steam bent

2 33

Figure 13c: Valley Product Application

ROOF VALLEY FLASHING DETAILS11

Figure 13b: Typical Saddle Flashing Detail

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.

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 metal should be underlayed with No. 30 ASTM D226 Type II or No. 30 ASTM D4869 Type IV 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).

Valleys: Certi-label® Shingles

On shake roofs, it is recommended that a strip of No. 30 ASTM D226 Type II or No. 30 ASTM D4869 Type lV 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® Shakes

Note: Check with your local building code official for minimum gauge/thickness requirement.

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

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)

Keep nails well away from the center of valley

Hidden felt

W valley metal 1/2" crimp

Figure 13d:

Roof Valley Flashing Detail

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

Counter flashing Jack

Plumbing stack

Certi-label® shake or shingle joint

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

Note: Check with your local building code official for minimum gauge/thickness requirement and step-flashing height.

1" minimum clearance around projection

Nails should not penetrate flashing flange underneath

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

ROOF FASTENER GUIDELINES

18" and 24" Tapersawn 6d Box 2

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

Certigrade® Shingles Type (in)

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

24" Shingles 4d Box 1 1/2

Fasteners

The Cedar Shake & Shingle Bureau prefers ® the use of nails, however if you choose to use staples they must be stainless steel Type 316 in locations within fifteen (15) miles of salt water. For locations outside of the salt water zone stainless steel Type 304 or Type 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.

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. For locations outside the salt water zone - nails must be stainless steel, Type 304, Type 316, or hot-dipped galvanized with a coating weight of

ASTM A 153 Class D (1.0 oz/ft ). Stainless steel nails offer the highest degree of corrosion resistance. Ring shank nails are used for better withdrawal resistance and in designated high wind zone areas. Some nail manufacturers offer nails specifically for wood shake or shingle roof application.

Contact the nail manufacturer for further information to ensure the fasteners used comply with listed requirements and are correct for your application.

Pressure Impregnated Treated Shakes and Shingles

Fasteners used with fire-retardant-treated (Certi-Guard®) and preservative-treated (Certi-Last®) shakes or shingles must be stainless steel Type 316. For specifics on installation, accessory building materials (flashing, etc), finishes and maintenance please contact the treatment company directly.

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

Check with building code official for local jurisdiction requirements

Nails must be stainless steel ype 316 in T locations within fifteen (15) miles of salt water. For locations outside the salt water zone - nails must be stainless steel Type , 304 Type 316, or hot-dipped galvanized , with a coating weight of ASTM A 153

Class D (1.0 oz/ ).

ft

Important Notes:

Check fastener requirements for your location (ie. salt water proximity or not.)

Underdriving or overdriving 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. Do not use electrogalvanized (EG) fasteners. Ensure the fasteners used comply with listed requirements.

Do not be fooled by “Number” 304 or 316 fasteners. The proper specification will include “Type” 304 or 316 – there is a content difference. Longer fasteners of the same quality are required for nailing hip and ridge product.

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 sheathing at least 3/4" or all the way through. Minimum nail lengths are shown in the fastener chart. 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.®

YES

Correct - flush with surface

NO

Underdriven

NO

Overdriven

Do not use electrogalvanized (EG) fasteners.

ROOF FASTENER GUIDELINES

Important Notes:

Underdriving or overdriving 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. Do not use electrogalvanized fasteners. Ensure the (EG) fasteners used comply with listed requirements.

Pressure Impregnated Treated Shakes and Shingles

Fasteners used with fire-retardant-treated (Certi-Guard®) and preservative-treated (Certi-Last®) shakes or shingles must be stainless steel Type 316. For specifics on installation, accessory building materials (flashing, etc), finishes and maintenance please contact the treatment company directly.

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

Check with building code official for local jurisdiction requirements

Example of a severely corroded electrogalvanized fastener. Ensure the correct fasteners are used. Corroded fasteners lead to serious roof system failures as well as unsightly staining.

Air flow Insulation

Figure 15c: Shed Roof

Figures 15a-15c: Ventilation Details

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

Roof rafter

Air flow

Figure 15a: Gable Roof With Attic

Figure 15b: Cathedral Ceiling With Partial Attic

If spray foam or foam boards are required to be applied to the bottom of the solid plywood sheathing (not spaced sheathing), it is strongly recommended to consult a building envelope specialist for potential issues of condensation and ultimate biodegradation of the solid plywood sheathing.

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, for normal installation. However if a barrier system of any type is used above the roof deck the attic ventilation shall be a minimum of 1:150.

Any modification to the vapor barrier system or addition of a vapor barrier system should only be done after consulting with your local building code official and a building envelope specialist. In some areas, building envelope specialists are regulated by government.

Check with your local building code official.

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.

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

1-2" diameter screened vents each roof rafter space

Check with building code official for local jurisdiction requirements

The CSSB recommends installing over plywood panel or dimensional lumber sheathing. If other sheathing materials are approved for use by your local building code official, the holding power of the fasteners should also be considered carefully. Contact local building code official for substrate (plywood) attachment fastener detail.

Note: Do not cover the entire deck with non-permeable barrier (including non-permeable underlayment). See CSSB technical bulletin “Asphalt-Saturated Organic Felt”.

Figure 16: Ridge Ventilation Detail

Airflow through ridge

Caulking

Roofing felt Felt folded back

VENTILATION DETAILS

Steep Slope (8:12 or greater) 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.

Severe Climate Areas

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.

Ridge Vents 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 code official.

Low Slope (6:12 or less)

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

Ridge ventilation product installed to manufacturer’s specifications

Certi-Ridge® shake or shingle ridge

Check with building code official for local jurisdiction requirements

Check fastener requirement for your location (i.e. salt water proximity or not.) Nails must be stainless steel ype 316 in locations within fifteen (15) T miles of salt water. For locations outside the salt water zone - nails must be stainless steel Type 304 Type 316, or hot-dipped galvanized , , with a

2coating weight of ASTM A 153 Class D (1.0 oz/ft ).

Cedar needs to breathe. If spray foam or foam boards are required to be applied to the bottom of the solid plywood sheathing (not spaced sheathing), it is strongly recommended to consult a building envelope specialist for potential issues of condensation and ultimate biodegradation of the solid plywood sheathing.

TIPS

Figure 17: Specialty Roof Deck-Vented Roof

SPECIALTY ROOF DECK DETAILS

Rigid insulation

Horizontal boards minimum 1 x 4

Vertical boards minimum 2 x 4

Wooden deck

Joist

Air space

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. 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.

Wood Deck

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.

A false plywood deck over insulation (not shown) can be a good choice. Space the false deck over the insulation by installing 2 x 4 or greater vertical members that are securely fastened through the insulation into the rafters. Attach the plywood to the vertical members and install the cedar roof over standard underlayment.

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

For vertical runs greater than 25 feet, contact a building envelope specialist for adequate ventilation requirements.

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

Check with building code official for local jurisdiction requirements

• 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.

• Cedar needs to breathe. If spray foam or foam boards are required to be applied to the bottom of the solid plywood sheathing (not spaced sheathing), it is strongly recommended to consult a building envelope specialist for potential issues of condensation and ultimate biodegradation of the solid plywood sheathing.

• For direct to deck application, consider using Certi-Last® products and also refer to high humidity details in this manual.

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

TIPS

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", as well as 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

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