Specification Guidelines

This information has been designed to aid architects, consultants and builders in specifying Certi-labelTM shakes and shingles. It suggests a standardized terminology and style for ordering in the hope of improving accuracy. It incorporates a general outline of the latest application information. Please note, however, that this is a specification guide only. The information in this manual is not intended to supercede local building codes. Refer to local building codes for more information.

General Specification Data

  1. The contractor shall cover all roof surfaces with (specify one type of the following product) Certi-Split® shakes/Certi-Sawn® shakes/Certigrade shingles bearing the Cedar Shake and Shingle Bureau's official grade marked label.
  2. Shakes/shingles for roofs shall be (specify grade and length).
  3. Shakes/shingles for outer courses shall be (specify grade and length).
  4. Shakes/shingles for undercourses shall be (specify grade and length).
  5. Roof shakes/shingles shall be laid with a weather exposure of (specify in inches).

Roof Application - Sheathing Boards

  1. Certi-Split® shakes/Certi-Sawn® shakes shall be applied over solid sheathing. A solid deck is recommended in seismic activity, hurricane and tornado regions and in areas where wind-driven snow is encountered and under pressure treated shakes and shingles. Please note: the only solid sheet sheathing tested with shakes and shingles is plywood. Check with your local building official for plywood thickness/dimensions. 
    Certi-Split shakes/Certi-Sawn shakes/Certigrade shngles may also be applied over spaced sheathing.
  2. All open sheathing shall be 1 x 4 or 1 x 6 boards (minimum 1 x 4 for both shakes and shingles).
  3. All solid sheathing shall be lumber or structural panels applied according to specifications of the American Plywood Association. Please note: the only solid sheet sheathing tested with shakes and shingles is plywood. Check with your local building official for plywood thickness/dimensions.

Roofing Felt Interlay (for shakes only)

  1. Contractor shall apply a 36" wide strip of No.30 ASTM D226 Type ll or ASTM D4869 Type lV roofing felt at the eave line. An 18" strip of No.30 ASTM D226 Type ll or ASTM D4869 Type lV roofing felt shall be applied over the top portion of the Certi-labelTM shakes and extend onto the sheathing. Bottom edge of felt shall be positioned at a distance above the butt equal to twice the weather exposure. Note: felt interlay between courses is not necessary when straight-split or taper-split shakes are applied in snow-free areas at weather exposures of less than one-third of the total shake length (three-ply roof). Contact the CSSB for more information.

Roofing General Application Data

  1. Certi-labeled shakes/shingles shall be at least doubled at all eaves.
  2. Butts of the Certi-labelTM shakes/shingles in the first course on roofs shall project 1 1/2" from the edge of the roof eaves to ensure proper spill into gutters and approximately 1" at gable and rake edge.
  3. Certigrade shingles shall be spaced apart not less than 1/4", not more than 3/8".
  4. Certi-Split® or Certi-Sawn® shakes shall be spaced apart not less than 3/8", not more than 5/8".
  5. Premium and Number 1 Grade Certi-labelTM shakes/shingles shall be applied with the weather exposures consistent with the following tables:
    Maximum Weather Exposure  
    Shingle Length 3:12 to 4:12 Roof Slope 4:12 and steeper
    16"  3¾"  5"
    18"  4¼"  5½"
    24"  5¾"  7½"
    Shake Length and Exposure
    18"  7½" 
    24"  10" 
    Note exception for resawn shakes: 24" x 3/8" shake= 7 1/2"  
  6. Chimney flashing shall extend up the chimney to a height not less than 3", up the roof slope to a point equal in height to the flashing on the chimney but never less than 1 1/2 times the Certi-label™ shake/shingle exposure. (All metal flashings should be painted.)
    Manufactured step flashing:
    5" x 7" shingle= 2 1/2" wall, 2 1/2" roof
    8" x 12" shake= 4" wall, 4" roof
  7. Apron counter flashing shall extend to within 1" of the surface of the finished roof.