Lumber grading - the very basics GUESS THE GRADE

[jeff...]

Hardwood Lumber Grading - the very basics

1) Calculate Board Feet (BF). Measure lumber width, thickness and length. One BF is a piece of lumber that is 1” thick 12” wide and 1 foot long or its equivalent. The formula to figure board feet is as follows:

Thickness * Width * Length
---------------------------- = BF
12
It’s best to round your measurements for simplicity sake. For example you find a piece of Oak lumber that measures 2 1/8” thick, 7 3/4“ wide and 8’ 3” long. Round down the thickness to the nearest 1/4”, width to nearest whole inch and length to the nearest whole foot. In our example we’ll make this piece of oak lumber a thickness of 2 inches, a width of 7 inches and a length of 8 foot, by rounding all three measurements down as specified above.

Thickness (2) * Width (7) * Length (8 )
--------------------------------------- = 9.3 BF
12

2) Calculate Surface Measure (SM). SM is nothing more than the surface measurement of one of the two faces of a piece of lumber. It’s calculated by measuring the width and length of the lumber and dividing the resultant by 12. If the SM calculated winds up to be a fraction, round the fraction to the nearest whole number, (.5 and above up, .49 and below down). Take note that thickness is not taken into account when determining SM.

Width * Length
--------------- = SM (rounded)
12

Again it’s best to round down width to nearest whole inch and length to the nearest whole foot. For our example piece of oak lumber, it measures an actual of 7 3/4” wide and 8’ 3” long. Again for calculation simplicity, we’ll round the width down to 7” and length to 8’

Width (7) * Length (8 )
----------------------- = 4.67 SM (round up) = 5 SM
12

3) Calculate Cutting Units (CU). A Cutting Unit is one inch by one foot or its equivalent. Again note, lumber thickness does not play a role in calculating CU. The formula for CU is merely the multiplication of the width and the length of a piece of lumber. The result is the number of cutting units contained within that piece of lumber. As we’ll see later SM and CU are vital in determining the grade of the piece of lumber.

Width * Length = CU

Similar to SM and for simplicity sake, it’s best to round down the lumber width to it’s nearest whole inch and it’s length to the nearest whole foot. So we’ll multiply 7 x 8 and arrive at 56 cutting units.

Width (7) * Length (8 ) = 56 CU

First a word about defect, for the purpose of my understanding the very basics of hardwood lumber grading, we’ll consider any knot, check, split, dote, hole, wane, worm holes, etc… a defect. What we are after is clear cuttings out of a piece of lumber. The grade rules cover defect and what’s allowed and what’s not per grade and species. Remember when reading this, that it’s my intent to cover grading rules details. Details regarding hardwood grading rules can be found in the latest release of the National Hardwood Lumber Association Hardwood Grade Book. http://www.natlhardwood.org/pdf/2007_Rules.pdf

4) Understand the basics of FAS grade requirements.

* FAS minimum board size is 6” wide by 8’ long. Any board irregardless of how clear it’s faces may be can not meet a FAS grade unless it meets or exceeds the minimum board size.
* A FAS clear cutting can be no smaller than 4 inches wide by 5 foot long or 3” wide and 7’ long. A cutting can be larger, but must be at least be these sizes.
* FAS number of allowable cuts is SM divided by four with a maximum of 4 cuts. The result is rounded down to the nearest whole number (drop any fractions)

SM
---- = FAS allowable cuts (Max 4)
4
* FAS CU Yield is SM times ten. This is the minimum allowable clear wood form the piece of lumber. For a board to make FAS ten twelve’s of it’s wood must be clear and be contained within the minimum FAS Clear cutting size and be cut in the FAS number of allowable cuts


5) example. The example below represents a piece of lumber that is 1 1/8” thick at it’s thinnest section. The black areas represent it’s poorest defective face and the dashed line is where the board would be cut to yield it’s greatest number of clear cutting units. Does it qualify for a FAS grade?

5-1) flip board to it’s poorest side, All hardwood is graded according to it’s most defect ridden face. Except for F1F and Select grades which I'll cover later, if I don't fall asleep first.

5-2) First calculate Board Foot (BF)

Thickness 1 * Width 10 * Length 8
---------------------------------- = 6.67 BF
12

5-3) Calculate the surface measure (SM)

Width 10 * Length 8
--------------------- = 6.67 SM (7 rounded)
12

5-4) Calculate the number of cutting units contained in the example

Width 10 * Length 8 = 80 CU


5-5) Calculate number of allowable FAS cutting to make grade

SM (7)
----- = 1.75 FAS allowable cuts (1 fraction dropped)
4

5-6) Calculate FAS CU Yield required

SM (7) * 10 = 70 FAS cutting units required


5-7) calculate CU of clear cutting, Width 9 * Length 8 = 72 Clear Cutting units​

In this example with one allowable cut the board has made the FAS Grade – this is assuming both sides of the board are clear and contained in the clear cutting units made by the single allowable cut. Also note if both edges were clear and there was defect within one foot of the end of the example board, it would also make FAS grade with a width of 10 and a length of 7 resulting in 70 clear cutting units and matching the minimum FAS CU required.

 

[DaveO]

Re: Lumber grading - the very basics

Thanks Jeff, that is excellent infomation to know, and you explained it well.
Dave

 

[Bas]

Re: Lumber grading - the very basics

Jeff, thanks for the info. Really helpful having this all together in one place. Readable post too! I usually I get lost right after the author states "we'll keep it simple" :SLEEP::SLEEP:

 

[jeff...]

Re: Lumber grading - the very basics

You guys ever read the rule book - it makes my head spin... And I'm used to reading some pretty technical garb. What I'm trying to do is pull out the very basics and cobble it together in some readable format that I can understand.
It's by no means meant to cover the grade rules in detail, it's more how I understand the basics after reading the rule book. So anyone please feel free to correct me if I'm wrong, I could be way off base...

 

[sapwood]

Re: Lumber grading - the very basics

Nice Jeff!
:eusa_thin How about submitting that as a PDF file for the Download Library?
'Cause I'll probably forget it by this evening :drunken_s

Thanks,
Roger

 

[FredP]

Re: Lumber grading - the very basics

Nice Jeff!
:eusa_thin How about submitting that as a PDF file for the Download Library?
'Cause I'll probably forget it by this evening :drunken_s

Thanks,
Roger

forget what?????????????? oh yeh! I forgot... must reread so i can forget again!:rolf: thanks for the reminder to forgeter jeff:slap:. good info buddy!:icon_thum

 

[McRabbet]

Re: Lumber grading - the very basics

Nice Jeff!
:eusa_thin How about submitting that as a PDF file for the Download Library?
'Cause I'll probably forget it by this evening :drunken_s

Thanks,
Roger

I completely agree with you Roger! Or, perhaps it should be extracted from here and added as a new entry in the FAQ Forum.

 

[Ray Martin]

Re: Lumber grading - the very basics

Nice Jeff!
:eusa_thin How about submitting that as a PDF file for the Download Library?
'Cause I'll probably forget it by this evening :drunken_s

Thanks,
Roger

Jeff,

This is a terrific reference. I agree with Roger. This should be in the library. Thanks for posting this.

Ray

 

[Kyle]

Re: Lumber grading - the very basics

Jeff,

Under #1.. Hardwood grading rounds up as well for width the thought process being that some will be over and some will be under average over volume is the median. I have found that commercial product purchased for resell is pretty spot on and uses this methodology.

EX. 7.75 is greater than 7.5 and rounds up to 8" . 7.4 would round down to 7"

another way to do it with a calculator is by inches..
2" x 8" x 8' or

2" x 8" x 96" = 1536 inches then divide by 144 = 10.67 bf

The wholesalers and high volume guys measure this way. We small sawmill guys are generous.

Under #3

A board that say is 12" wide and 1' thick and 9 feet long may have a defect (knot or hole) on an edge and still be considered FAS due to the cutting units.

I always advertise as SELECT due to the stringent FAS criteria.

Also Walnut and cherry sap are NOT considered defects.

Determination of Grade is not easy and the graders go to school for certification for the short course or whole enchilada.

A new grade that seem to be arising more often is FAS 1F (1 clear face)

 

[bonewood]

Re: Lumber grading - the very basics

Answer my PMs on that other site:slap:

 

[Grgramps]

Re: Lumber grading - the very basics

Jeff, I think we all benefit by understanding how board feet are calculated. (It's not like buying 5 lbs of potatoes.)

Is there a difference when calculating board feet of green wood and wood that has been dried? The reason for asking is because when I bought from Gennetts in Asheville they made the calculation to account for the shrinkage of the kiln dried lumber.

I haven't experienced this elsewhere so I wonder if this is just their policy? It has probably been a couple of years since buying from them after finding other lumber sellers did not follow that method. I can't say how they presently calculate.

Roy

 

[jeff...]

Re: Lumber grading - the very basics

Jeff,

Under #1.. Hardwood grading rounds up as well for width the thought process being that some will be over and some will be under average over volume is the median. I have found that commercial product purchased for resell is pretty spot on and uses this methodology.

EX. 7.75 is greater than 7.5 and rounds up to 8" . 7.4 would round down to 7"

another way to do it with a calculator is by inches..
2" x 8" x 8' or

2" x 8" x 96" = 1536 inches then divide by 144 = 10.67 bf

The wholesalers and high volume guys measure this way. We small sawmill guys are generous.

Under #3

A board that say is 12" wide and 1' thick and 9 feet long may have a defect (knot or hole) on an edge and still be considered FAS due to the cutting units.

I always advertise as SELECT due to the stringent FAS criteria.

Also Walnut and cherry sap are NOT considered defects.

Determination of Grade is not easy and the graders go to school for certification for the short course or whole enchilada.

A new grade that seem to be arising more often is FAS 1F (1 clear face)

Kyle I hoped you and some of the sawyers would chime in here... You make some good points... although I'm not quite done with this yet still need to do 1F1, Select, #1 and #2 grade basics. I'm trying my best to stay away from species specific grading only because the NHLA are very clear about species allowances and defect.

I inquired NHLA about certification - believe it or not they told me their is no "certification" for hardwood grading but there is for softwood. Because of structural safety concerns.

Your right on target when you say "The wholesalers and high volume guys measure this way. We small sawmill guys are generous." Us small guys need to keep things simple cause we do most everything ourself.

I'm not an "official" grader, grading was always kind of a mystery to me. Now that I have figured out the basics. It's no longer a mystery - actually it's very definable and mathematical driven. There's really no smoke or mirrors only some simple to understand math formulas.

I ordered a grade stick to grade dry lumber, I'm going to figure out how to use it.

Thanks

 

[jeff...]

Re: Lumber grading - the very basics

Jeff, I think we all benefit by understanding how board feet are calculated. (It's not like buying 5 lbs of potatoes.)

Is there a difference when calculating board feet of green wood and wood that has been dried? The reason for asking is because when I bought from Gennetts in Asheville they made the calculation to account for the shrinkage of the kiln dried lumber.

I haven't experienced this elsewhere so I wonder if this is just their policy? It has probably been a couple of years since buying from them after finding other lumber sellers did not follow that method. I can't say how they presently calculate.

Roy

Roy - NHLA Rule #4 states:

"4. Lumber shall be inspected and measured as the inspector finds it,
of full length, width and thickness. No allowance shall be made
for the purpose of raising the grade, except that in rough stock,
wane, and other defects which can be removed by surfacing to
standard rough thickness shall not be considered. Nothing herein
shall be construed as prohibiting the shipper from improving the
grade or appearance of the lumber at time of or prior to shipment.
The surface grade as determined by the cutting yield shall first be
established by the inspector, after which the thickness shall be
determined. Thickness does not determine grade.
After grade and thickness have been determined, special features,
such as the amount of forty-five degree radial grain for
classification as quarter sawn lumber and the amount of figure as
specified for figured woods and some quartered woods, shall be
considered.

see (page 7 rule 5). ---> http://www.natlhardwood.org/pdf/2007_Rules.pdf

Also see page 7 Rule 8
8. Lumber should be properlymanufactured of good, averagewidth
and lengths. It should be edged and trimmed carefully to produce
the best possible appearancewhile conserving the usable product
of the log. Shipments of rough lumberwill admit 25%of surfaced
lumber when it is of the specified rough thickness. Contracts for
green lumber should specify dimensions required to provide for
shrinkage in drying.

Also see Standard Kiln Dried Rule and Kiln Drying of Hardwood Lumber page 59

Thanks

 

[Turtlewood]

Re: Lumber grading - the very basics

So is it fair to say that the prices Wall Lumber and The Hardwood Store list on the webpage without grading are "select" as well and not FAS?

I always kinda wondered about that, as they don't say on the pricing page.

-Kevin

 

[Kyle]

Re: Lumber grading - the very basics

"I inquired NHLA about certification - believe it or not they told me their is no "certification" for hardwood grading but there is for softwood. Because of structural safety concerns."

http://www.natlhardwood.org/school.asp?userid=
http://www.natlhardwood.org/school-tuition.asp?userid=
thats the 14 week course in memphis..

there is also a short course..(3-4 days) depending upon where its taught..lost in VA.
http://www.natlhardwood.org/events.asp

There is a short course being taught in Raleigh in May
Event Details : 3-Day Lumber Grading Short Course

Event Date: May 13, 2008 to May 15, 2008
Time: 8:00 a.m.
Place: Raleigh, NC

This course is designed for anyone wanting to become familiar with NHLA Lumber Grading Rules. It provides yardmen, sawyers, edgermen, sales and office staff with management personnel with an introduction to lumber inspection. Students should bring a notebook and grading stick if they have one.

Registration fees:

Location:

North Carolina State University
Raleigh, NC

Contact: Patti Woodbury

Phone: 919-515-5637
Fax: 919-515-8739

Click here to download printable registration form

Instructors: Joe Denig/Mark Horne

» Contact patti_woodbury@ncsu.edu

 

[lottathought]

Re: Lumber grading - the very basics

Threads like this are gold to many of us newer WWr's.
Frankly, this is one of the few places we can go and have faith that the info is accurate.

 

[Ivey]

Re: Lumber grading - the very basics

Kyle, thanks for posting this information. I am going to try to make the Raleigh short course.
Jeff, looks like you're getting a handle on this grading thing. I wish that I had the softwood certification so that I could stamp some of this nice looking pine and cypress that I'm sawing. It would nice to see a house built from it along with all of the horse barns...

 

[jeff...]

Re: Lumber grading - the very basics

Kyle, thanks for posting this information. I am going to try to make the Raleigh short course.
Jeff, looks like you're getting a handle on this grading thing. I wish that I had the softwood certification so that I could stamp some of this nice looking pine and cypress that I'm sawing. It would nice to see a house built from it along with all of the horse barns...

Ivery check the hardwood grade book - http://www.natlhardwood.org/pdf/2007_Rules.pdf
It's got rules for Cypress but not for pine. I haven't looked at the Cypress rules in detail, but it would give you a very good idea what's coming off your mill.

I was going to attend one of those 3 day classes, seems like they pop up just about everywhere, till I found out from NHLA there is no certification required to be a hardwood inspector / grader. So I ordered the Grade book and decided I would try and figure it out for myself instead.

Thanks

 

[jeff...]

Re: Lumber grading - the very basics

6) To understand FAS1Face (F1F) and Select grades, first an understanding of #1 common basic requirements is needed. Both F1F and Selects must contain #1 grade on their poorest face and FAS on their better face. There are specific grade which rule allowances for minimum board size, wane and other characteristics for both FAS and Select grades which I’ll cover later. If there is money to be made cutting lumber it’s in the #1 common grade, a company that can produce a lot of #1 common can be in a good financial situation. A saw mill company that can maintain a steady stream of 14” diameter and larger logs and be able to turn the logs frequently during sawing in order to get the best grade possible can produce quite a bit of #1 common. The grade rules for #1 common are not near as stiff as they are for the upper grades.

Width - Lumber must be at least 3 inches or wider.

Length – Boards must be no less than 4 foot long or no greater than 16 foot long.

Size of cuttings - A #1 common clear cutting can be no smaller than 4 inches wide by 2 foot long or 3” wide and 3’ long. A cutting can be larger, but must be at least be these sizes.

Number of allowable cuts - is SM +1 divided by three with a maximum of 5 cuts. The result is rounded down to the nearest whole number (drop any fractions).
SM + 1
--------- = #1 common allowable cuts (Max 5).
3

#1 Common cutting unit (CU) Yield - is surface measurement (SM) times eight. This is the minimum allowable clear wood form the piece of lumber. For a board to make #1 Common eight twelve’s of it’s wood must be in clear cuttings and be contained within the minimum #1 common clear cutting size and be cut in the #1 Common number of allowable cuts

Pith - The amount of pith allowed for #1 common is no more that one half the length of the board.

7) #1 Common example - The example below represents a piece of lumber that is 8 3/4" wide, 2 1/8” thick and 8' 2" long. The black areas represent it’s poorest defective face. The shaded area is considered waste because of defect and the dashed line are where the board would be cut to yield it’s greatest number of clear cutting units. Does it qualify for a #1 common grade?

7-1) First calculate Board Foot (BF) Remember to round width and length down

Thickness 2 * Width 8 * Length 8
---------------------------------- = 10.67 BF
12

7-2) Calculate the surface measure (SM) Remember to round width, length down and the resultant down

Width 8 * Length 8
--------------------- = 5.3 SM (5 rounded)
12

7-3) Calculate the number of cutting units contained in the example, ) Remember to round width and length down

Width 8 * Length 8 = 64 CU


7-4) Calculate number of allowable #1 common cuttings to make grade. Remember to drop the fraction

SM (5) +1
------------- = 2 #1 common allowable cuts
3

7-5) Calculate #1 common CU Yield required

SM (5) * 8 = 40 #1 common cutting units required

7-6) Calculate amount of clear Cutting Units, In this example there are two, one is 3” wide by 8’ long which is 24 cutting units and the other is 5” wide by 4’ long to equal 20 cutting units. The sum of both cuttings equal 44 which exceeds the allowable #1 common grade by 4 cutting units.

Also we fall into our maximum of 2 cuts allowed one is a rip cut and the other is a cross cut. Our narrowest board is 3” and our shortest board is 4’ - Yep this example makes the #1 common grade.

I think the easiest way to determine if a board meets the #1 common grade, is look at its poorest face and say to yourself (is two thirds of this board clear)? If the answer is yes, chances are pretty high it’s #1. I also think a lot of grading in the industry is done by sight, graders have seen so many boards they just know what grade it’ll be, But you could always do the math and find out for sure…

When I get some time, I’ll try and tackle F1F, then Select – stay tuned… If I made any errors please feel free to correct me I'm trying to learn and it might be very possible I'm all wet here. Any comments welcome...

Thanks

 

[jeff...]

Re: Lumber grading - the very basics

Wondering if I bored everyone or if folks are just uninterested in this topic?

Should I continue with the other grades (F1F / Select and #2)? Then maybe finish it off with a species and drill down into the specifics of that particular species.

I don't see a need to continue if there is not any interest.

Thanks