P15A - Lumber Grading - Rev 23A.pdf

Lumber Grading 1 Lumber Grading • Very specialized trade • • Formal schooling “Inspectors” or “Graders” are certified for Hardwood or Softwood grading Softwood and hardwood have different grading criteria depending on application examples: • http://www.midwesthardwood.com/images/stories/page_...

Lumber Grading 1 Lumber Grading • Very specialized trade • • Formal schooling “Inspectors” or “Graders” are certified for Hardwood or Softwood grading Softwood and hardwood have different grading criteria depending on application examples: • http://www.midwesthardwood.com/images/stories/page_i mages/Midwest/Gallery/Meister/19_Meister_Grading.JPG – Hardwood destined for furniture making – Softwood used in millwork – Softwood destined for the construction industry 2 1 Lumber Grading - General • Every piece of lumber is unique • The lumber grading process sorts/groups pieces of lumber into grade categories or “grades” defined by the applicable Lumber Grading Rules • Purpose of Grading: Ensures pieces of lumber with “equivalent qualities” are assigned the same grade regardless of the log or mill it came from • Lumber Grading Rules: A set of technical and detailed requirements used to assign a grade category to a piece of lumber 3 SOFTWOOD GRADING 4 2 Softwood Lumber Grading Types of Softwood Lumber • Dimensional Lumber Surfaced softwood Nominal 2” – 4” thick 2” or more wide Designed for use as framing members such as joists, planks, rafters, and studs – Strength is the main criteria – – – – • Boards – 1” thick lumber for a variety of uses depending on appearance and to some degree strength 5 Softwood Lumber Grading • Canadian Lumber Standards Accreditation Board (CLS) – controls the identification and certification of softwood lumber to be used in Canada, exported from Canada, or manufactured in accordance with standards approved in Canada. • Each piece of lumber graded is stamped by the agency grading the material • Stamp information http://www.plib.org/services/lumber-grading/ – Registered trademark symbol of the grading agency (1) – Mill or grader identity (2) – Grade of Lumber (3) – Species or combination of species (4) – Moisture content when lumber was surfaced (5) 6 3 Softwood Lumber Grading • Softwood Dimensional Lumber (and Boards) are typically dressed or machined to dimension (example: 2 x 4) • The Canadian Standards (CSA) association allows softwood lumber to be dressed or machined in three different ways – S-Dry or KD – lumber has been dried to a moisture content not exceeding 19% when it is surfaced – MC 15 or KD15 – lumber has been dried to a moisture content not exceeding 15% when it is surfaced – S-GRN – lumber is surfaced or machined to size when the wood has a moisture content higher than 19% 7 Softwood Lumber Grading TYPE Dimensional Lumber CATEGORIES Light Framing For general construction where high strength values are not needed; for example plates. Structural Light Framing Used where higher bending strength ratios are important; for example, roof trusses. Structural Joists and Planks Used where high strength value is needed (similar to SLF, but wider); for example, joists for floors. Studs Used where strength is important such as vertical uses in load bearing walls – cut to stud lengths. GRADE • • • • Construction Standard Utility Economy • Select Structural • No. 1 • No. 2 • No. 3 • Stud 8 4 Softwood Lumber Grading TYPE Boards CATEGORIES Selects For finishing where fine clear appearance and high quality are important. Commons Many uses; from finishing to general construction. GRADE • B & Better – best clear wood in appearance and strength • C Select – Fine clear appearance. • D Select – Fine clear appearance; usually of finish quality on one side only • 2 Common – Fine knotty appearance; for example, used in panelling and shelving • 3 Common – Fine appearance and has strength; for example, used in fencing, sheathing, and lower grade panelling. • 4 Common – For general construction; for example, sheathing, concrete forms and subfloors. • 5 Common – Strength and appearance are not important; for example, bracing and dunnage. 9 HARDWOOD GRADING 10 5 Hardwood Lumber Grading National Hardwood Lumber Association • Founded in 1898 to standardize the grades for hardwood lumber • Creator and keeper of the North American hardwood lumber grading rules • Before the NHLA was created, lumber was graded by mills on an individual basis http://www.nhla.com/ Link to the NHLA Rule Book: http://issuu.com/nhla/docs/2015_rulebook_final/25?e=14506784/10572319 11 Terminology Board Size vs Cutting Size examples Cutting: Rectangular area on a board that is knot and defect free Note: defects that will be removed when the board is dressed can be included in a clear cutting Board Size: 12’ x 8” Cutting Sizes: 4’ x 4” 6’ x 8” Board Size: 12’ x 8” Cutting Sizes: 4’ x 8” 12 6 Hardwood Lumber Grading • Boards are rated based on how usable they are – Large clear cuttings are more usable than small clear cuttings • Factors used to determine Grade: 1. Dimensions of the board in length and width 2. Dimensions of the Clear Cuttings in length and width 3. The number of Clear Cuttings 4. Area of Clear Cuttings as a percentage of Total Board Area (Yield) 13 Standard Hardwood Grades • Firsts & Seconds (FAS) • Select • No. 1 Common • No. 2 Common • No. 3 Common There are other grades that will not be covered: FAS-1-Face, Sound Wormy, etc 14 7 • Firsts & Seconds (FAS) – – – – – Best grade of Hardwood lumber Minimum 8’ long boards Graded from the poorer side of the board 83% yield Use in applications requiring wide long attractive material • Select – – – – – – Minimum 6’ long boards (smaller than FAS) Graded from the best side of board Cutting size requirements are the same as FAS 83% yield Use in applications where only one good face is visible Grade of poor side can not be lower than No 1 Common 15 • No. 1 Common – – – – Graded from the poorer side of the board 67% yield Suitable for projects requiring medium to shorter lengths Commonly referred to as “cabinetmaker’s grade” • No. 2 Common – Graded from the poorer side of the board – 50% yield – Limited usefulness to cabinetmakers because of short lengths of clear cuttings • No. 3 Common – Graded from the poorer side of the board – 25% yield – Seldom used in cabinetmaking 16 8 Hardwood Lumber Grades Number of Clear Cuttings (depends on board and cutting sizes) Grade Side Graded From Minimum Board Size Minimum Cutting Size Firsts & Seconds FAS Worst 6" x 8' 4" x 5' 3" x 7' 1-4 SM x 10 (~83%) Selects Best 4" x 6' 4" x 5' 3" x 7' 1-4 SM x 10 (~83%) No. 1 Common Worst 3" x 4' 3" x 3' 4" x 2' 1-5 SM x 8 (~67%) No. 2 Common Worst 3" x 4' 3" x 2' 1-7 SM x 6 (~50%) No. 3 Common Worst 3" x 4' 3" x 2' unlimited SM x 3 (~25%) % Clear (Minimum) The information in this table has been simplified Refer to the NHLA Grading Rules for full details 17 Red Oak FAS ahec.org/hardwoods/pdfs/illustratedgradingguide.pdf 18 9 Red Oak No. 1 Common ahec.org/hardwoods/pdfs/illustratedgradingguide.pdf 19 Red Oak No. 2 Common ahec.org/hardwoods/pdfs/illustratedgradingguide.pdf 20 10 Terminology Surface Measure (SM) • Area of the board in square feet rounded to the nearest whole number Cutting Units (CU) • An area 1” wide and 1’ long 21 Steps Performed when Grading Lumber 1. Find the Surface Measure of the board 2. Calculate the minimum number of cutting units required for each grade based on the SM (10 x SM, 8 x SM, 6 x SM, 3 x SM) 3. Select the poor face of the board and visualize it into a number of clear cuttings (use the better face for Select) 4. Determine the total number of clear cutting units 5. Compare the clear cutting units to the minimum number required for each grade (calculated in step 2) and determine the potential grade of the board 6. Confirm the other requirements are met (board size, cutting size, number of cuttings) The Grader does all this in about 15 seconds! 22 11 Determining the Grade 𝑆𝑢𝑟𝑓𝑎𝑐𝑒 𝑀𝑒𝑎𝑠𝑢𝑟𝑒 = Worst Side 8 𝑖𝑛𝑐ℎ𝑒𝑠 ×12 𝑓𝑒𝑒𝑡 = 8.0 𝑠𝑞𝑢𝑎𝑟𝑒 𝑓𝑒𝑒𝑡 12 𝑖𝑛𝑐ℎ𝑒𝑠 𝑝𝑒𝑟 𝑓𝑜𝑜𝑡 Round to nearest whole number à SM = 8 GRADE REQUIREMENTS FAS 10 x SM = 80 cu No. 1 Common 8 x SM = 64 cu No. 2 Common 6 x SM = 48 cu No. 3 Common 3 x SM = 24 cu 𝐶𝑙𝑒𝑎𝑟 𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝑈𝑛𝑖𝑡𝑠 = 6” × 4! + (8” × 6′) 𝐶𝑙𝑒𝑎𝑟 𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝑈𝑛𝑖𝑡𝑠 = 24 𝑐𝑢 + 48 𝑐𝑢 𝐶𝑙𝑒𝑎𝑟 𝐶𝑢𝑡𝑡𝑖𝑛𝑔 𝑈𝑛𝑖𝑡𝑠 = 72 𝑐𝑢 Cutting Unit requirement for FAS à not satisfied Cutting Unit requirement for No. 1 Common à satisfied Minimum Board Size requirement for No. 1 Common (3” x 4’) à satisfied Minimum Cutting Size for No. 1 Common (3” x 3’ or 4” x 2’) à satisfied Maximum Number of Cuttings for No. 1 Common ( 1 to 5 depending on board size) à satisfied GRADE is No. 1 Common 23 Lumber Grading Video https://www.youtube.com/watch?v=o92zfsgJW6M (It’s Complicated!) 24 12 DISCUSSION Why not simply buy the highest grade of lumber? Why not simply buy the lowest (cheapest) grade of lumber and just cut around the defects? 25 Ordering Hardwood Lumber Must specify 1. 2. 3. 4. 5. 6. http://www.divinesolution.org/order.jpg Quantity (in BdFt) Thickness (in quarters of an inch) Grade Species Surfacing or Rough Sawn Width/Length requirements if any or RWL 7. Moisture Content Example: 2000 BdFt, 4/4, FAS, Honduran Mahogany, RGH, RWL, KD to 6 – 8% MC 26 13 Receiving Lumber http://www.granitehardwoods.com/images/truck.jpg • Driver is under no obligation to unload • Truck must be unloaded in a timely manner to allow truck to continue • Signed receipt does not indicate acceptance of load • If load is disputed 1. 2. 3. Contact Area Rep If still not satisfied, talk to company management If still not satisfied call NHLA a) b) c) http://www.irionlumber.com/uploads/images/Walnut% 20Page/Walnut%20Pack%20(Large).jpg They will regrade Loser pays for regrading Application for regrading must be filed within time period defined within the applicable grading regulation (typically 10 days) 27 Lumber Storage • Adequate support at regular intervals along its length • Proper stacking • Kept at least 4” off concrete floors • Protected from direct sunlight • Excessively long or short boards stored separately for convenience • RH and Temp conducive of a MC of 6% - 8% 28 14 Questions? 29 15