NLGA Grading Rules

The following information in reproduced exactly as it is printed in the book “NLGA (National Lumber Grades Authority) Standard Grading Rules for Canadian Lumber”

 

The text uses terminology that is not commonly used in the UK market, however to maintain the accuracy of the information we have not made any changes.   The term “Finish,” refers to “Trim Boards;” the terms “Panelling” and  “Ceiling,” refer to “Tongue & Groove Cladding” and the term “Drop Siding” refers to “Shiplap Cladding.”  “Siding” is the North American term for “Cladding.”

 

Western Red Cedar 

Western Red Cedar finish, panelling, ceiling & drop siding, K.D.

2” & Thinner, 2” & Wider

 

200.  Western Red Cedar Finish is customarily shipped kiln dried and surfaced four sides.  Grade descriptions for Finish and Panelling are based on a piece 8” wide and 12’ long.  Grade descriptions for Ceiling and Drop Siding are based on a piece 4” wide and 12’ long.  The number of characteristics in larger or smaller pieces may vary in proportion to the size of the piece.

Pieces of finish 5” and narrower are graded from the best face and both edges.  Pieces 6” and wider are graded from the best face and one edge.

Pieces of Panelling, Drop Siding and Ceiling run to pattern may be partially surfaced or hollow or scratched back.

 

“Saw Texture” is available in all grades of Western Red Cedar and, as the name implies, is a rough finish put on the face of a piece to give it a textured finish.  Material supplied with this finish shall in all ways adhere to the grades, sizes and patterns as specified, except that it shall be graded from the textured face.

There are three grades of Western Red Cedar Finish, Panelling and Ceiling:  “Clear Heart,” “A,” and “B.”

If F.G. or V.G. only is desired, it must be so specified.  Otherwise mixed grain (M.G.) may be shipped at shipper’s option.

In occasional pieces of “A and Better” the tongue or lap in panelling or lap in panelling and siding may be 1/16” narrower and Ceiling with a tongue 1/8” or more in width is permissible.

 

200a. “Clear Heart” – Finish, Panelling, Ceiling & Drop Siding

This is the highest grade of Finish, Panelling, Ceiling and Drop Siding produced.  The exposed face shall be all heartwood with many pieces being absolutely clear.  Some pieces may exhibit a few minor characteristics which do not detract from their high appearance and quality.

Characteristics and limiting provisions are:

Cup                                         - very light

Skips                                       - very light on back

Torn or Raised Grain            -very light

Warp                                      - very light

 

200b. “A” – Finish, Panelling, Ceiling & Drop Siding

This grade is only slightly less restrictive than “Clear Heart.”  The “A” grade is ideally suited to applications where finishing requirements are less exacting.

Characteristics and limiting provisions are:

Checks                                    - small

Cup                                         - light

Sapwood                                - not limited

Skips                                       - occasional light on edges and back

Torn or Raised Grain            - light

Warp                                                  - light

Knots                                      - 2 small, sound, tight or their equivalent

 

200c. “B” – Finish, Panelling, Ceiling & Drop Siding

Although the “B” grade permits larger and more numerous characteristics than “Clear Heart” and “A” grades, it is highly serviceable and often yields short lengths of fine appearance from longer stock.  Many pieces have a fine appearance on one side, the reverse side showing larger or more numerous characteristics.

 

Characteristics and limiting provisions are:

Checks                                    - not limited

Cup                                         - medium

Pin Holes                                - limited                     

Sapwood                                - not limited

Skips                                       - hit and miss on either face and grooved edge in pattered stock; approx. 1/8” scant on edge.

Splits                                       - short

Tongue or Lap                       - narrow, must be at least 1/16” in width

Torn or Raised Grain            - not limited

Wane                                      - 1/8 width for ¼ the length and ¼ the thickness, or its equivalent in an occasional piece

Warp                                                  - medium

Knots                                      - 4 approximately 1” or their equivalent

Cutout                                    - a 3” cutout – 3’ or more from either end of pieces 12’ & longer is permissible in the shipment

 

200d. Glued-Up Finish, Panelling, Ceiling & Drop Siding

End-glued, edge-glued or a combination of end and edge-glued Finish, Panelling, Ceiling and Drop Siding is intended to be interchangeable in use value with one-piece stock of the comparable grade.  The characteristics of the grade are the same as for one-piece stock.  Additional requirements for which the producer is responsible are:

 

a)    Exterior glue line equal to heat cured 50-50 melamine urea glue.

b)   Adequate glue line strength for usual handling and fastening.

c)    Appearance shall be suitable for intended finishing of each grade.

 

Bevel Siding, K.D.

201.  Western Red Cedar Bevel Siding is produced by resawing kiln dried surfaced lumber on a bevel to produce two pieces thicker on one edge than the other and is most commonly used as exterior siding, giving a horizontal shadow line effect.  Except for siding intended for rough side use, bevel siding is graded on the surfaced side with characteristics and limiting provisions enumerated in the grades applying to the exposed width.  Grade descriptions are based on a piece 6” wide by 12’ long.  Occasional tolerance in thickness is permitted, approximately 1/32” over or under in any one piece.  The thick edge permits minor characteristics that do not detract from the appearance of the piece in use.

“Saw Texture” is available in all grades of Western Red Cedar Bevel Siding and as the name implies is a rough finish put on the face of a piece to give it a textured finish.  Material supplied with this finish shall in all ways adhere to the grades, sizes and patterns as specified, except that it shall be graded from the textured face.

There are five grades of Western Red Cedar Bevel Siding: “Clear V.G. Heart,” “A,” “B,” “Rustic” and “C.”  Special items, namely ½” x 4” and ½” x 5” sizes, ½” x 6” square edged and ¾” x 6” rabbeted siding, are usually graded “CLEAR V.G. HEART” and “A” combined for the first grade

Normal head lap for regular Bevel Siding is 1”.  This portion of the thin edge may contain characteristics that will be covered when laid and will provide a suitable backing.

In rabbeted siding, depth of rabbet conforms to thickness of thin edge, width of rabbet is ½”.

 

Finished Sizes:

Nominal Sizes                                              Dressed Sizes

Board Measure                                Thick                         Thin

Thickness                 Width                         Edge               Edge               Width

1/2”                            4”                                15/32”           3/16”             3 1/2 

1/2”                            5”                                15/32”           3/16”             4 1/2”

1/2”                            6”                                15/32”           3/16”             5 1/2”

1/2”                            8”                                15/32”           3/16”             7 1/4”

5/8”                            8”                                9/16”             3/16”             7 1/4”

5/8”                            10”                              9/16”             3/16”             9 1/4”

3/4”                            6”                                3/4”                3/16”             5 1/2”

3/4”                            8”                                3/4”                3/16”             7 1/4”

3/4”                            10”                              3/4”                3/16”             9 1/4”

3/4”                            12”                              3/4”                3/16”             11 3/4”

 

Lengths are 3’ and longer in multiples of 1’

 

Nested Bundling (N.B.):

Bundles are 6’ to 16’ or longer.  Bundles 10’ and longer contain specified layers of 3’ to 7’ lengths.

Full Length Bundling (F.L.B.):

All pieces in the bundle conform to the corresponding length of the bundle.  The length assortment is normally 6’ to 16’ or longer but may include a percentage of 3’ to 5’ bundles, as specified by the shipper.

Shorts:

“CLEAR” and “A” Grade –

-       6” & narrower, not more than 20% of the footage may be 6’ & 7’ bundles.

-       8” & wider, not more than 15% of the footage may be 6’ & 7’ bundles

“B” Grade & Rustic

-       Not more than 20% of the footage may be 6’ and 7’ bundles.

“C” Grade –

-       No percentages specified.

 

Bundling Schedule:

                                    F.L.B. & N.B.                         N.B. Only

                                    Layers Per Bundle              Layers Nested in 10’ & Longer

3/4” x 6” to 12”                    6                                              2

1/2” x 5” to 8”                      10                                           3

5/8” x 8” & 10”                     10                                           3

1/2” x 4”                                12                                           4

201a. “Clear V.G. Heart” – Bevel Siding

The exposed width is all heartwood and free from imperfections and presents a vertical grain appearance for 3/4 the width from the thick edge.  The thick edge may contain light torn or raised grain.    

201b. “A” – Bevel Siding

“A” – Bevel Siding may be furnished in mixed grain.

 

Characteristics and limiting provisions are:

Skips                                       - very light on thick edge

Torn or Raised Grain            -very light on face, light on thick edge

Knots                                      - 1 small, sound, tight in occasional piece

 

201c. “B” – Bevel Siding

“B” – Bevel Siding may be furnished in mixed grain.

 

Characteristics and limiting provisions are:

Pin Holes                                - well scattered in occasional piece

Skips                                       - very light, light on thick edge in occasional piece

Torn or Raised Grain            -light, medium on thick edge in occasional piece

Knots                                      - 4 small sound, tight or equivalent smaller in occasional piece

Cutouts                                   - cutouts are permitted which can be removed by cutting out not more than 5% of the length of the piece, not exceeding one cutout in pieces 6’ to 9’ and two cutouts in pieces 10’ & longer.  The minimum length of the piece of each segment after cutting must not be less than 18”.

 

201d. “Rustic” – Bevel Siding

Pieces are graded from the resawn side.  Thick edge may be rough or surfaced.  The grade may include pieces too thin to dress to standard size, but not more than 1/16” scant thickness.

Some pieces may contain:

Holes                           - pin – well scattered

Knots                          - 4 – sound, tight, small

Lengths are random, with percentage as specified by the shipper.

 

201e. “C” Bevel Siding

Although this grade admits larger or more numerous characteristics than “B” grade, it often yields short lengths of fine quality.  This grade may include stock too thin to dress in standard sizes.  Lengths are random with percentages as specified by the shipper.

 

201f. Factory Primed Bevel Siding

Factory primed products shall be identified with a stamp or label by the producer.

 

201g. Glued-Up Bevel Siding

End-glued, edge-glued or a combination of end and edge-glued Bevel Siding is intended to be interchangeable in use value with one-piece stock of a comparable grade.  The characteristics of the grade are the same as for one-piece stock.  Additional requirements for which the producer is responsible are:

a)    Exterior glue line equal to heat cured 50-50 melamine urea glue.

b)   Adequate glue line strength for usual handling and fastening.

c)    Appearance shall be suitable for intended finishing of each grade.