Installation FAQ

Number four grade shingles are a utility grade for undercoursing of double coursed sidewalls only. They are not a roofing material and they are not to be used as a starter course on roofs.

Cut a board the same width as your shingle exposure and a length where you can lay out shingles. Tack it in place being careful not to damage the underlying roof shingles, then lay out and nail a course. Move it up and tack it in place again. Lay out and nail into shingles and repeat five to six courses. Move along, and chalk line every five or six courses, being careful not to damage the underlying roof shingles.

Waste factor will vary, depending upon quality of product, roofing contractor’s experience, and aesthetic look desired. Contact your Member Contractor/Installer for more details about your particular job; unfortunately this is not a question that the CSSB can answer for you as it is project-specific.

CSSB does not recommend using spray foam underneath the plywood before installing cedar shakes or shingles on top of it. Spray foam tends to create an air barrier and a non-ventilated base. This can lead to premature deterioration of the internal side of cedar shakes and shingles which can cause cup and curling issues. An adequately ventilated base is required to ensure the long life of the cedar roof.

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 shakes and shingles is plywood. Check with your local building official for plywood thickness/ dimensions. See the CSSB’s New Roof Construction Manual.

The two words are used interchangeably in the roofing industry.

“Strapping” is another term for nailing strips. It is also called “open lathe application”, “spaced sheathing” or “skip sheathing”. See the CSSB’s New Roof Construction Manual.

The CSSB recommends using an 18″ wide strip of No.30 ASTM D226 Type ll or ASTM D4869 Type lV roofing felt laid over the 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. Note: Building officials MAY approve eliminating felt interlayment between shake courses when tapersawn or tapersplit shakes are applied in snow-free areas at weather exposures of less than one-third the total shake length (3-ply roof). ALWAYS check with your local Building Official for project approval PRIOR to deviating from standard application guidelines.

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 interlay also increases the roof’s insulating value. The felt interlay system forces water to the surface, thus assisting the proper water shedding in your roof.

Yes. Different regions of the country use different words to describe the same thing.

Yes. Cedar shake application is a system of shakes with interwoven felt.

Yes. Cedar shake application is a system of shakes with interwoven felt.

The CSSB recommends ASTM D226 Type II or ASTM D4869 Type IV roofing felt. House wrap typically allows moisture to flow behind the shingles, where these ASTM standard roofing felts will not.

A strip of felt, metal and/or rubber flashing should be laid under the hip and ridge product. See the CSSB’s New Roof Construction Manual for more details.

The untreated shingles will last longer and the roof system will work better if you have an airspace directly below the shingles to allow them to breathe and dry out. It will also allow summer condensation to run out from under the shingles. Shingles directly on eave protection will not dry out very readily and will not last as long as the rest of the roof shingles. A continuous ventilation product may be installed only over the eave protection, under the shingles, to maximize ventilation.

Fastener-sealing eave protection is very helpful at the eaves and the valleys. If No.30 ASTM Type ll or No.30 ASTM Type lV roofing felt is installed on the remainder of the roof with a continuous ventilation product on top of the felt and eave protection you will have a great roof. If using a Certi-Last® or shake felt system product you only need the felt and eave protection.

No. 30 ASTM D226 Type ll or ASTM D4869 Type lV roofing felt.

Copper flashing can be used with a cedar roof in most areas, with the exception of areas that are exposed to acid rain areas east of the great lakes.

Heating stacks require 1″ space. Walls, skylights and windows that are flashed with metal should be closed. Check with your local Building Official regarding this particular application question.

It is unlikely that the cedar is causing the deterioration of the flashings: any metal will rust if exposed to certain elements in the air. Many tropical areas do not allow any kind of galvanized sheet metal on any type of construction.

Yes, you can nail through the copper.

Please refer to the CSSB’s New Roof Construction Manual and Exterior and Interior Wall Manual for specific details.

Your project is experiencing what is called “fishmouthing”. The bowing or curving of the shingles is due to inadequate joint or keyway spacing. When the shingles naturally expand and contract with moisture content due to weather conditions, proper joint or keyway spacing provides the room that allows them to remain flat. Contact your Member Contractor/Installer for more assistance.

You can use a nail gun to install cedar shingles and shakes. However, the nail heads must not be overdriven into the surface of the shingles. See the CSSB’s New Roof Construction Manual for more details.

You should never see staples or nails in the joints or keyways between shakes or shingles. If you do, it means that fastener was installed incorrectly. It could also indicate other unseen incorrect installation. Contact your local Member Contractor/Installer for details.

You can nail the woven corners together, but the CSSB suggests using hot-dipped galvanized nails and pre-drilling the holes to prevent splitting.

Read the CSSB Fastener Chart and Nailing Diagram, Exterior and Interior Wall Manual.

Nails and staples MUST be stainless steel Type 316 in locations within fifteen (15) miles of salt water. Please refer to the CSSB’s New Roof Construction Manual and Exterior and Interior Wall Manual for specific details.

Certi-label shakes and shingles have only been tested on plywood decking. Make sure you use a very good quality hot dipped galvanized or stainless nails that are ring shanked to hold the roof to the OSB and check with your local Building Official to see if this type of application is permitted.

Check with your local Building Official for requirements in your area.

No. You should remove all existing ridge caps, then apply a water proof strip of felt, metal, fastener-sealing eave protection to ensure that the ridges or hips are water tight. Finally, install the new ridge caps.

Assuming local Building Official approval for this type of installation is obtained, you should use the length of nail recommended for that specific material. Add the thickness of the existing roof and this gives you the nail length required for the fastener to penetrate ¾” or more into the sheathing. Refer to the CSSB’s New Roof Construction Manual.

Assuming local Building Official approval for this type of installation is obtained, you should use the length of nail recommended for that specific material. Add the thickness of the existing insulation and this gives you the nail length required for the fastener to penetrate ¾” or more into the sheathing. Refer to the CSSB’s Exterior and Interior Wall Manual.

As long as the shingles are dry when stained it doesn’t seem to matter whether they are painted on all 4 sides or just on the front side. A local, professional painting expert may be able to provide you with further guidance.

Yes, but most times you need to install additional window and door trim to ensure that the product lies flush with windows and doors. Sometimes this additional trim requirement makes it less expensive to tear off the old siding and start from scratch. Look at the diagram in the CSSB’s Exterior and Interior Wall Manual for more details.

Put the bottom step flashing on the starter course, then bend the bottom of the step flashing out about 1″ to 1 ½” away from the wall. The top of the step flashing is still under the siding or plaster. You do have to trim the top starter course shingle with a triangle shaped cut to allow this. This does leave a triangular shaped void between the bottom of the step flashing, the wall, and the shingle, that can be filled with caulk. This will divert the water away from the lower wall so the water does not run down the wall.

You can install grooved shingles this way, but it is a rather expensive installation. You have paid more for the grooves put on the face of the shingle, and they are manufactured with the intent of having the grooves facing out, to the weather.

Slope is defined as the change in height (rise) as compared to the distance up the roof area (run) and is measured in inches. For example, a slope of 4:12 means 4 inches of rise for every 12 inches in run. Some people call slope “pitch”, but the technically correct term is “slope”.

Any slope of 3:12 or more is fine for cedar shingle application.

No they do not. Standard shingles tend not to last as long on unvented sheathing; ventilation should be provided on solid sheathing for the best results. Please consult the CSSB’s New Roof Construction Manual for more information.

If you have an area between the roof and the sheathing ridge and no other ventilation had been provided, ridge vents are a good idea.

Good ventilation is essential and can be achieved in a variety of ways; check with your Member Contractor/Installer to see if nailing strips (spaced sheathing) or a continuous ventilation product is the best choice for your roofing project. Both choices are effective, however the nailing strips (spaced sheathing) are typically ¾” thick and the ventilation product is usually ¼” thick: if the rafters are very long the nailing strips (spaced sheathing) will provide more air circulation.

On steep slope roofs, the correct ridge vent 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 medium slope roof. However, by using a ridge vent that is pliable and at least 8 ½” 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 vent material to the Certi-label® shakes or shingles. Proper nailing of the ridge units will create a serviceable application.

Please contact the manufacturer of the ventilation product for warranty details. The CSSB does not administer warranties for any type of ventilation product.

Your installer should take care to ensure a high enough moisture content to avoid splitting the product due to brittleness.