Regional exceptions to the standard NHLA grades
The NHLA grades cover the majority of commercial hardwood species growing in the USA. The following is a brief summary of the various species and colour sorting that can be ordered from the American supplier.
Red alder
Grows exclusively in the Pacific Northwest between the vast stands of softwood timber such as Douglas fir and pine and is the most important commercial hardwood in this region. The grading rules for red alder are geared more for specific end uses and appearance. Alder is graded using NHLA 'Pacific Coast Red Alder Rules published in the “NHLA Rules for the Measurement & Inspection of Hardwood and Cypress”. The rules were developed on the West Coast of the USA with those manufacturers and exports in mind.
The key grading points include grading from the better face rather than poor side as in the Standard NHLA Grading Rules; pin knots are regarded as character and no defect. The primary grades include Superior (Select & Better), Cabinet (No. 1 Common) and Frame (No 2. Common) which are similar to the uses as for the standard NHLA grades.
An exceptional cabinet wood typically sold surfaced (planed) and often cut to specific lengths and widths. Consult with your local supplier for a more detailed explanation of the alder grades and products available.
Walnut
Considered the elite of the American hardwoods, walnut is the favourite of the darker woods for fine furniture, interiors and gunstocks. Walnut grows in widely scattered stands throughout the eastern half of the United States, primarily in the Midwest. Historically, the grading rules for FAS walnut have been refined to encourage better use of this valuable species. Because of this, FAS walnut grades allow for smaller boards, both in width and length. Natural characteristics are also admitted to a greater extent than the standard NHLA grade rules for other species. A detailed explanation can be found in the NHLA rules book. Consult with your local supplier for the walnut grades and products available.
Colour sorting
In addition to sorting for grades or selecting specific widths, various species are commercially sold at an added value when colour is also considered. It is important to note, colour in this explanation refers to sapwood and heartwood.
Number 1 and 2 white
A colour selection typically made on hard maple, but can be applied to any species where sapwood clear cuttings are desired, such as ash, birch, and soft maple.
Number 1 white means both faces and edges of the clear cuttings must be all sapwood.
Number 2 white means that one face and both edges of the clear cuttings must be sapwood and not less than 50% sapwood on the reverse face.
Sap and Better
Commercially sold when only one face of the board needs to be sapwood. Usually applied to the same species as Number 1 and 2 White, although just a little less stringent. In Sap and Better every board should have a minimum of one sapwood face in the clear cuttings.
Red one face and Better
Commercially sold when a minimum of one face of the board needs to be heartwood. Usually applied to species such as cherry, oak, walnut, gum, and even birch and maple in certain applications. What the producer is looking for in this specification is that all clear cuttings must have a minimum of one heartwood face.
There is a wide range of additional options open to American hardwood producers in sorting and selecting specific lengths, widths and even grain patterns. If these can be agreed individually between producers and buyers, there can be benefits by making modifications to the standard grades shown in this guide. This may also assist with improving the yield from each log and thus contributing to the sustainability of the forest. It may also reduce costs to both sides or add value to the delivery.
Definition of a Sound Cutting
A cutting free from rot, pith, shake and wane. Texture is not considered. It will admit Sound knots, bird pecks, stain, streaks or their equivalent, season checks not materially impairing the strength of a cutting, pin, shot and spot worm holes. Other holes 1/4" or larger are admitted but shall be limited as follows: one 1/4" in average diameter in each cutting of less than 12 units; two 1/4" or one 1/2" to each 12 units and on one side only of a cutting.
The steps in determining grade
- Determine species.
- Calculate the Surface Measure (SM).
- Determine the poor side of the board.
- From this poor face, calculate the percentage of clear wood available. Note: If Number 1 Common is the grade of the poor face, check the better face to see if it will grade FAS for the F1F or Selects grades to be achieved.
- Once the grade is determined, check for any special features such as sapwood or heartwood cuttings for special colour sorts.
- Sort to bundles according to buyer and seller specifications.
Summary of US hardwood lumber grades
| FAS | FAS 1 FACE | SELECTS | NO 1 COMMON | NO 2A & 2B COMMON | |
|---|---|---|---|---|---|
| Board Size | 6”x8’
|
Same as FAS for species being graded
|
4”x6’
|
3”x4’
|
3”x4’
|
| Minimum Cutting Size |
4”x5’ 3”x7’
|
Best face of board must grade FAS Poor face of board must grade No 1 Common |
Best face of board must grade FAS
Poor face of board must grade No 1 Common |
4”x2’ 3”x3’ |
3”x2’ |
| Minimum Yield |
Surface measure x10 83%
|
Best face of board must grade FAS Poor face of board must grade No 1 Common |
Best face of board must grade FAS Poor face of board must grade No 1 Common |
Surface measure x8
|
Surface measure x6
|
| Formula to determine Number of Clear Cuttings |
Surface measure 4 |
Best face of board must grade FAS Poor face of board must grade No 1 Common |
Best face of board must grade FAS Poor face of board must grade No 1 Common |
Surface measure +1 |
Surface measure |
Lưu ý:
- This chart summarises the main requirements for the standard grades. For complete information, consult the appropriate section of the NHLA Rule Book.
- For kiln dried lumber, 1 ⁄2" shrinkage is permitted for the minimum size board in each grade.
- No. 2A Common requires clear cuttings.
- No. 2B Common is a utility grade requiring cuttings to be Sound.