Lumber Grades
Copyright © Texas Education Agency, 2011. All rights reserved.
Lumber Dimensions
What are the dimensions of this board?
“2X4“
Someone measure it for me.
“1½X3½“
Why are there two different sets of numbers?
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Nominal
2x4
1x6
2x8
1x2
Two by Six
1 x 12
One by Four
4x4
6 x 12
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Actual
1½x3½
1½x5½
1½x7½
¾x1½
One and a half by five and a half.
¾ x 11 ¼
¾x3½
3½x3½
5 ½ x 11 ¼
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Nominal VS. Actual
Nominal 2 x 6
Actual 1 ½ x 5 ½
Nominal 2 x 8
Actual 1 ½ x 7 ½
Is there a pattern?
2 X 10 and 2 x 12
Actual 1 ½ x 9 1/4 , 1 ½ x 11 1/4
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Lumber Size Chart
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Grading Terms

Boards – Consists of members up to 1 ½ “
thick and 2 “ and wider

Light Framing – Consists of members 2” to 4”
thick and 2” to 4” wide.
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Grading Terms

Joists – Consists of members 2” to 4” thick
and 6” or wider.

Beams – Consists of members 5” and thicker
by 8” inches and wider
Copyright © Texas Education Agency, 2011. All rights reserved.
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Grading Terms

Posts and Timbers – Consists of members 5”
x 5” and greater, approximately square.
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Grade Stamps
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Grade Stamp

The Grading Agency

This symbol indicates
which agency is
certifying the quality of
the lumber.
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Grading Stamp

The Species of Lumber

Indicates species by
individual species or
species combination.
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Grade Stamp

The Grade

The grade designation:
Grade name, number,
or abbreviation.

Indicates the quality of
the material.
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Grade Stamp

The Mill Identification

Firm name, brand, or
assigned mill number.
Allows the agency to
identify the individual
mill whenever
necessary.
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Grade Stamp

The Moisture Content

Condition of seasoning:
Indicates the condition
of seasoning at the
time of surfacing.
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Grading Chart
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Grading Lumber Class
Construction
Standard
Utility
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Grading Lumber Class
Select Structural
Grade
1
2
3
Stud
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In Summary:




What is the difference between a nominal
and an actual dimension?
At what lumber size does the pattern for
lumber dimensions change?
What are the common similarities between
the 1 x 4 and the 2 x 4?
Give one part of the Grade Stamp.
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