Thermawood Hemlock diagonal and vertical rainscreen-1

Decking, Siding and Dimensional Lumber Sizes

 

 


Decking, Siding and Lumber Sizes



Wood lumber, siding, and deck board sizes can be confusing for many. A “1x6” doesn’t measure 1” x 6”. Here’s a simple way to understand actual lumber sizes and decking sizes and why.

Wood lumber sizes, especially finished lumber, are usually expressed in terms of nominal thickness and nominal width in inches, then the actual board length in feet. For example, a 1x6x10 would be 1 inch (nominal) thickness x 6 inches (nominal) width by 10 feet (actual) length.


Dimensional Lumber Sizing


Nominal sizing is how decking, siding and lumber is bought and sold. When you visit a lumber yard or home improvement store, you will see lumber sizes expressed as 1x4, 2x4, 2x6, 4x4 and more. These measurements refer to the “nominal” thickness and width of boards, dimensional lumber, posts, beams and other common solid sawn lumber products.

The actual lumber sizes are different than the nominal description of the wood. For example, a 2x6 does not actually measure 2” x 6” when it is finished. 2x6 is the actual size of the raw lumber before it is processed. It measures approximately 1.5 inches thick by 5.5 inches wide after it is finished (dressed). The lumber keeps this nominal size name throughout the process. After the logs are harvested and cut into raw lumber boards, the boards are kiln dried or air dried. this changes the sizing a little. Then the dried board is planed and milled until it reaches its industry accepted finish size of 1-1/2” x 5-1/2”. Because of the original size of the lumber, including all the wood fiber in the board, and all the costs of cutting, planing, and drying, the board is still called a 2x6.


Here’s a list of the most common decking, siding and dimensional lumber sizes we carry in stock:

Nominal Size Actual Size (Inches Fractions) Actual Size (Inches Decimal) Actual Size (Metric)
Decking and Board Sizes
1x4 3/4" x 3-1/2" .75″ x 3.5″ 19mm x 90mm
1x6 3/4" x  3-1/2" .75″ x 5.5″ 19mm x 140mm
1x4 Max 13/16" x 3-1/2" .83″ x 3.5″ 21mm x 90mm
1x6 Max 13/16" x 5-1/2" .83″ x 5.5″ 21mm x 140mm
1x8 3/4" x 7-1/4" .75" x 7.25" 19mm x 184mm
1x10 3/4" x  9-1/4" .75" x 9.25" 19mm x 235mm
1x12 3/4" x  11-1/4" .75" x 11.25" 19mm x 286mm
5/4x4 1" x 3-1/2" 1″ x 3.5″ 25mm x 90mm
5/4x6 1" x 5-1/2" 1″ x 5.5″ 25mm x 140mm
5/4x8 1" x 7-1/4" 1″ x 7.25″ 25mm x 184mm
5/4x10 1" x 9-1/4" 1″ x 9.25″ 25mm x 235mm
5/4x12 1" x 11-1/4" 1″ x 11.25″ 25mm x 286mm
Wood Rainscreen Siding Sizes
1x4 11/16" x 3-1/4" .6875" x 3.25" 17mm x 82mm
1x6 11/16" x 5-1/4" .6875" x 5.25" 17mm x 133mm
5/4x4 15/16" x 3-1/4" .9375" x 3.25" 23mm x 82mm
5/4x6 15/16" x 5-1/4" .9375" x 5.25" 23mm x 133mm
Tongue and Groove T&G Siding Sizes
1x6 11/16" x 5" .83" x 5" 21mm x 120mm
Dimensional Lumber Sizes
2x2 1-1/2" x 1-1/2" 1.5″ x 1.5″ 38mm x 38mm
2x4 1-1/2" x 1-1/2" 1.5″ x 3.5″ 38mm x 90mm
2x6 1-1/2" x 1-1/2" 1.5″ x 5.5″ 38mm x 140mm
2x8 1-1/2" x 1-1/2" 1.5″ x 7.25″ 38mm x 184mm
2x10 1-1/2" x 1-1/2" 1.5″ x 9.25″ 38mm x 235mm
2x12 1-1/2" x 1-1/2" 1.5″ x 11.25″ 38mm x 286mm
Heavy Timbers, Posts, and Beam Sizes
3x4 2-1/2" x 3-1/2" 2.5″ x 3.5″ 64mm x 90mm
3x6 2-1/2" x 5-1/2" 2.5″ x 5.5″ 64mm x 140mm
3x8 2-1/2" x 7-1/4" 2.5″ x 7.25″ 64mm x 184mm
3x10 2-1/2" x 9-1/4" 2.5″ x 9.25″ 64mm x 235mm
3x12 2-1/2" x 11-1/4" 2.5″ x 11.25″ 64mm x 286mm
4x4 3-1/2" x 3-1/2" 3.5″ x 3.5″ 90mm x 90mm
4x6 3-1/2" x 5-1/2" 3.5' x 5.5" 90mm x 140mm
4x8 3-1/2" x 7-1/4" 3.5" x 7.25" 90mm x 184mm
4x10 3-1/2" x 9-1/4" 3.5" x 9.25" 90mm x 235mm
4x12 3-1/2" x 11-14" 3.5" x 11.25" 90mm x 286mm
6x6 5-1/2" x 5-1/2" 5.5″ x 5.5″ 140mm x 140mm

 

DOWNLOAD THE LUMBER DIMENSIONS SIZES CHART HERE


Decking, siding and lumber are all sold by the linear feet. For example, a 1x6x10 board would be sold as 10 lineal feet.

Please feel free to contact us with any questions you may have relating to any Mataverde products or an upcoming lumber, decking or siding project requiring our assistance.


Other helpful related information:

Decking and Siding Stock Lists here

Glossary of Lumber, Decking and Siding Terms

Decking Square Footage Calculator