Helping woodworkers online for over 20 years

Lumber Dimensions and terminology

 

mensio

Purchasing material can be confusing, we see terms we are not familiar with, and the material we buy is smaller than we thought, hopefully this page will shed some light on the subject.

Hardwood and Softwood

This has to do with the type of tree the wood came from, not the hardness of the wood, for example balsa is a hardwood. Softwoods come from coniferous trees with needle like leaves, most are evergreen. Hardwoods come from deciduous trees with broad leaves

4/4, 5/4, and 6/4 ?

Material will often be listed like this, it simply means that the thickness of the material is measured in quarter of an inch increments, hence 4/4 is one inch thick, 8/4 is two inches thick. Verbally 4/4, 5/4 or 6/4 would be said, "four quarter, five quarter and six quarter."

S2S

This means material is surfaced on both faces.

S4S

This means that the material is finished on all four sides, for example what what we refer to as a 1 X 4 was a piece of rough sawn material 1" thick and 4" wide and is reduced to 3/4" X 3 1/2" when run through a planer.

Lineal Foot

Lumber priced by the linear foot means that you pay for each running foot of the material, prices will increase proportionately for wider or thicker material.

Board Foot

One board foot equals 144 cubic inches of material, prices are usually given per thousand feet. To calculate board feet multiply the width in inches by the thickness in inches by the length in inches and divide by 144.

The advantage to suppliers is that only one price has to be given for each grade and species of material since length and width are covered in the volume calculation.

The chart below gives the board feet in various lengths and widths of material one inch thick, for thicker material multiply by the thickness of the material.




Common Defects

There will often be defects in the lumber you are selecting, the five most often found are shown below:

Lumber Defects



Twist

A twisted board is when the opposite corners are higher than the other two corners.

Crook

This is when the board is curved looking at it from the top.

Bow

A bowed board curls up from end to end.

Cup

A cupped board is curved along the length of the board.

Kink

A kink in a board is when the board is straight most of the length but then there is a sudden bend toward one side.

 

 

Red Oak

Walnut

Maple

Cherry