welcome to western red cedar lumber grading · slide 2 wrc lumber grading lumber grading items nlga...

Welcome toWestern Red Cedar

Lumber GradingPresented by

Rob Johnson

WRC Lumber Grading Lumber Grading ItemsNLGA Clear Bevel SidingNLGA Clear Finish and PanelingNLGA Knotty Paneling and SidingWRCLA Clear DeckingWRCLA Knotty Decking Inland BoardsAppearance TimbersExam Questions

Coastal Log Grade ZonesClear Zone - Appearance: Clear Bevel Siding, Clear

Finish and Panelling, Clear Decking (most valuable zone)

Factory Zone - Cutting Qualities:

Flitches and Shop Lumber

Construction Zone: Knotty Decking, Knotty

Bevel Siding, Knotty Panelling, Inland Boards

Sections of the Tree

Roots: anchor the tree; absorb moisture and mineral salts. The resulting solution, called sap, passes up the trunk to the crown.

Crown:a system of branches and twigs which bear the needles. They form the crown where the sap from the roots is transformed into tree food.

Trunk:provides mechanical support for the

crown, conducts liquid materials between the roots and the crown, stores reserve food.

Parts of the Trunk

Pith

The trunk consists of five (5) parts The woody part is divided into Pith, Heartwood and Sapwood

sap rising up from the roots is conducted through the sapwood Between the Sapwood and the Outer Bark is the active growth layer of

the tree called the Cambium where all new cells of wood and bark originate (the main purpose of the outer layer of bark is protection)

HeartwoodSapwoodCambium

Bark

Sapwood vs. Heartwood Heartwooddarker in colour, infiltrated materials functions as support lower moisture content

Sapwood lighter in colour functions as a conductor of foodhigher moisture content

Durability of Sapwood vs. Heartwood

Sapwood in a living tree is rarely attacked by fungus

Heartwood in the living tree, however, is more susceptible to attack

Annual Rings the two layers of bands, the springwood and

summerwood, together make up what is called an “annual ring”

one annual ring represents one year’s growth

Springwood the layer of wood cells put on

by the tree during the spring rapid growth forms wood cells

with large cavities and thin walls

appear as lighter coloured bands

Summerwood the layer of wood cells put on by the

tree later in the season slower growth forms wood cells with

small cell cavities and thick cell walls appear as darker

coloured bands

Summerwood vs Springwood

the summerwood cellsare thick-walled and therefore stronger and denser than the thin-walled springwood cells

a guide to strength and density is the amount of summerwood present

Rate of Growth

used to describe the relative width of growth rings

rate of growth requirements are sometimes part of a grading rule

Cell Structure tiny hollow longitudinal cells

running parallel to the length of the trunk

in addition to the longitudinal cells there are cells that run radially from the pith to the bark called “wood rays”

wood rays comprise 7% to 10% of the total volume of wood

Tree and Branch Growth

A tree begins its growth in height by sending up a single shoot, (leader) the end of the growing season small buds are formed at the top of the leader (terminal bud).

Tree and Branch Growth

Year after year the growth in height will be from the terminal budand the length of the branches (twigs) from the buds at the ends.

Knot Formation and Quality

• Sound - show no indication of unsound wood. It may be natural colour or black(not necessarily intergrown.)

• Unsound - contains decay• Tight - so fixed by growth, shape or position that it will retain its place in the

piece.

Knot Quality

Sound - show no indication of unsound wood. It may be natural colour or black (not necessarily intergrown.)Unsound - contains decayTight - so fixed by growth, shape or position that it will retain its place in the piece.

Sound and Tight

Encased

Unsound

Grain the fibres in wood and their direction, size,

arrangement, appearance or quality

Wood GrainWood GrainVertical Grain

Flat Grain

DiagonalGrain

Forms of KnotsForms of KnotsRound Knot

Oval Knot

Spike Knot

Spiral Grain and Slope of GrainSpiral Grain caused when tree fibres

take a spiral course around the trunk

edge of the piece

Slope of Grainin lumber, the deviation of the line of fibres from a straight line parallel to the sides (edges) of the piece

Intended Uses of Grades Clears - graded for their

attractive features (appearance)

Construction lumber is graded for strength and tight construction when sawing for strength

items, lumber should be produced as flat grain

WRC Clear Bevel SidingNLGA Para. 201-201E

Grade Names

Clear V.G. Heart

A

Rustic

Basic Size 6” x 12’ 6” x 12’ 6” x 12’

Faces Graded

Surfaced Face Surfaced Face Rough Face

Knots Not Permitted 1 S&T Knot = 3/4” ave. dia.

4 S&T Knots = 3/4” ave. dia.

Sapwood Not Permitted Any Amount Any Amount

WRC Clear Bevel Siding - Head lap

Plain Bevel – 1” head lap Rabbeted Bevel – ¾” head

lap

Basic Size

6”

Basic size is expressedin surface units (S.U.). and is equal to 72 S.U.

Faces Graded – Smooth Face

NLGA Western Red CedarClear Bevel Siding

Grade names:Clear V.G. HeartARustic – graded from rough

face

Angle of Grain

7½”

55/8”

Clear V.G. Heart

Pieces must present a vertical grain appearancefor ¾ of the actual width measured from the thickedge.

Knot measurement - average diameter of the longest dimension (A) and the narrowest dimension (B).

Knots

Intergrown Knot growth rings are partially or completely intergrown

on one or more faces with the growth rings of the surrounding wood

Loose/Not Firmly Fixed Knot not held tightly in place by growth, shape or position,

cannot be relied upon to retain its place

film of barkencompassing it

Encased Knot surrounded with pitch or bark and is not intergrown

with the growth rings of the surrounding wood

Unsound Knot a knot that contains decay

Star Checked Knot a knot that contains seasoning checks, usually

occurring from the pith to the edge of the knot

Sapwood

Clear V.G. Heart

Sapwood is not permittedanywhere on the exposedwidth.

NLGA WRC Clear Bevel SidingReview Basic Size? Normal “head lap”? Faces graded? Knots are measured? Purpose Intended? Sapwood permitted in

“Clear VG Heart”?

6” x 12’ = 72 S.U. 1” Surfaced face Average Diameter Appearance No

Clear Finish/PanelingNLGA - Para. 200 - 200CGrade Names Clear Heart A B Basic Size 8” x 12’ 8” x 12’ 8” x 12’ Faces Graded Best Face Best Face Best Face Knots - 2 - 3/4” S&T 4 - 1” Sapwood - Permitted Permitted

Cutout - - 3” - 3’ - 12’ lgr

Basic Size

8”Basic size is expressedin surface units (S.U.).

4”

Finish and Panelling Drop Siding and Ceiling

Faces Graded

5” & narrower 6” and wider

Finish

Panelling and Ceiling

Sapwood

sapwood

sapwoodheartwood


Knots

Wane bark or lack of wood from any cause, except eased

edges, on the edge or corner of a piece of lumber

Wane

Basic Wane EquivalentWider

EquivalentLonger

Cut Out

3”

NLGA WRC Clear Finish and Panelling - Review

Basic Size? Knots are measured? Purpose Intended? Sapwood in “Clear Heart”? Faces graded - Panelling? Faces graded - 1”x6” Finish? Faces graded - 1”x4” Finish?

8” x 12’ = 96 S.U. Average Diameter Appearance No Patterned face Best face + 1 edge Best face + both edges

Knotty Paneling/SidingNLGA Rules - Para. 204-204B

Grade Names Select Quality Faces Graded - Panelling Best or patterned face

Faces Graded - Siding Sawn or Textured face

S & T Knots Permitted Permitted

NFF/Unsound Knots Not Permitted 1” - 2 / 12’

Spike Knots 1/2 Actual Width Equivalent

Cutout Not Permitted 3” - 3’- 12’ & longer

NLGA Western Red CedarKnotty Panelling and Siding

Grade names:Select Knotty.Quality Knotty.

Faces Graded:Panelling – Patterned Face.Bevel Siding – Rough Face


Knots

Spike Knots Spike knots are measured between lines parallel to the

edges.

Cut Out

3”

NLGA WRC Knotty Panelling and Siding - Review

Knots are measured? Basic Size? Faces graded - Panelling? Faces graded - Siding? Spike knots - Select Knotty? Cutout in Quality Knotty? Purpose Intended?

Average diameter None Patterned face Rough face 1/2 actual exposed width 3” / 3’ / 12’ & longer Appearance & Weather

resisting qualities

Specifying WRCLA Cedar Decking WRCLA grade categories of decking provide a choice of clear grades

(WRCLA Clear Decking) or rustic knotty grades (WRCLA Knotty Decking) for outdoor decks of any style and budget

WRCLA Clear DeckingGrade Names Architect Clear Custom Clear

Faces Graded Patterned face and corresponding 1/2 edge

Basic Size 8” x 12’ 8” x 12’

Knots Two, 3/4”, S & T (per basic size)

Three, 1” S & T Four, 1/2” NFF or Unsound (per basic size)

WRCLA Clear Decking Thickness classifications:2” and Under thicknesses3” and 4” thicknesses

Grade names:Architect Clear DeckingCustom Clear Decking

Faces Graded All sizes and all grades are graded from the

patterned face and corresponding ½ of edges.

Patterned face½ of edge

½ of edge

Basic Size8”

Basic size is the size of a piece onwhich a specific number ofirregularities are permitted.

A standard basic sized piece is 8” x 12’.

Knot measurement is by average diameter of the longest dimension (A) and the narrowest dimension (B).

Knots

WRCLA Clear Decking Review

Grade names?

Basic size? Knots are measured? Faces graded?

Purpose Intended?

Architect Clear and Custom Clear

8” x 12’ = 96 S.U. Average diameter Best face and corresponding

1/2 edges Appearance

WRCLA Knotty Decking

Grade Names Architect Knotty Custom Knotty

Faces Graded Patterned face and corresponding 1/2 edge

Knots S & T 4” Widths = 11/2” 6” Widths = 2”

4” Widths = 2” 6” Widths = 2-7/8”

Unsound or NFF Knots

Not Permitted 4” Widths = 1” 6” Widths = 11/2”

Slope of Grain 1 in 10 1 in 8

Reverse Face Wane

1/3T, 1/4W, Full Length

1/3T, 1/3W, Full Length

WRCLA Knotty Decking

Grade names:Architect Knotty.Custom Knotty.

Faces Graded All sizes and all grades are graded from the

patterned face and corresponding ½ of edges.

Patterned face½ of edge

½ of edge

Knot measurement is by average diameter of the longest dimension (A) and the narrowest dimension (B).

Knots

WRCLA Knotty Decking Review

Grade names?

Knots are measured? Faces graded?

Purpose Intended?

Architect Knotty and Custom Knotty

Average diameter Best face and corresponding

1/2 edges Strength and Appearance

Inland Boards - WWPA Para. 30.12 – 30.14

Grade Names #2 Common #4 Common

Faces Graded Best Face

Knots - S & T Permitted Permitted

Knots - NFF or Unsound

Not Permitted Approximately 2/3 Actual Width

Spike Knots Equivalent Equivalent

Wane Face: None Allowed Back – 1/2T, 1/6W, 1/3L

On Face: 1/2T, 1/8W, 1/6 L Heavy on Back

WWPA Inland Boards

Grade names:#2 Common#5 Common

Faces Graded Grade is determined from the best face,

regardless of dressing.

Round Knot produced when the limb is cut at approximately

right angles to the length of its axis

found on flat grainsurfaces

Oval Knot produced when the limb is cut at slightly more

than right angles to the length of its axis

found on angledgrain surfaces

Spike Knot produced when the limb is cut either lengthwise

or diagonally to the length of its axis

found on vertical grain surfaces

Knot Measurement in BoardsA

B

A

B

BA

Round or Oval Knot Spike Knot

Irregular Knot Spike Knot

Wane

#2 Common 1” x 8” x 6’

Basic Wane EquivalentWider

EquivalentLonger

WWPA Inland Boards Review

Grade names? Knots are measured? Faces graded? Purpose Intended? Wane allowed on the

face in #2 Common?

#2 Common and #5 Common Average diameter Best face Construction No

Appearance TimbersGrade Names Appearance Builders Grade Faces Graded All Faces All Faces

Slope of Grain 1 in 6 1 in 4

Wane 1” across corner, ¼ Length (max 1-1/2”)

1” across corner F.L. additional 2” for 1/4 Length

S & T Knots 3” 3-1/2”

NFF/Unsound Knots

One 2” per 4’ or equivalent

3-1/2”

Faces Graded Graded from ALL faces and both ends. The worst or most serious characteristic

determines the grade.

Slope of Grain

edge of the piece

Slope of Grain A term used to express the amount of deviation of

the wood fibres from a line parallel to the edges of a piece.

The deviation is expressed as a ratio (i.e. 1 in 10,1 in 8).

Illustration shows slope of grain of 1 in 4

24”

6”

Appearance Timbers

Grade names:Appearance GradeBuilder’s Grade

Round and Oval Knots

Average the size on worst face. The number of knots is not controlled.

Appearance Timbers - Review

Knots are measured? Purpose Intended? Faces graded?

Average diameter Strength All faces plus both ends

Pieces are LabelledThey are Categorized By Team, Number, Item, Size, and Length

B 1Clear Bevel Siding

1" x 6" - 6'Review

A 1Clear Bevel Siding

1" x 6" - 6'Review

welcome to western red cedar lumber grading · slide 2 wrc lumber grading lumber grading items nlga...

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