Wood Terms - A Lumber Glossary from A - Z

A complete "Woodipedia" of lumber terms for experts & amateur woodworkers alike.

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Woodipedia Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Wood Terms that Start with "I"
Lumber Glossary Term Definition

A beam whose cross section resembles the letter “I”. One in which the top and bottom flanges (such as 2x4s) are connected by thinner material (such as OSB or plywood).


Incense Cedar

Idle Time

Scheduled non-operating time.

Idler Wheel

In band sawing, it is the unpowered half of the pulley-like system that turns the blade. Its primary purpose is to guide the blade.

  • Yellow-olive heartwood
  • Variegated streaks and stripes
  • Usually straight grain, often wavy or curly
  • Fine and even growth rings
  • Fine to medium texture
  • Moderately stable, fairly hard and heavy
  • Works easy with both hand and machine tools
  • Used for high-class furniture, cabinet making, high-grade flooring, paneling and gunstocks.
Imperfect Manufacture

Includes all defects or blemishes produced in manufacturing.


Wood in which the cell walls have been impregnated with synthetic resin so as to reduce materially its swelling and shrinking.


Inch or inches.

Incipient Decay

An early stage of decay in which hyphae have invaded the cell structure, sometimes discoloring the wood, but have not perceptibly reduced the hardness of the wood.

Incised Wood

Wood with slots cut into the side of the wood so that preservative chemicals can penetrate more deeply during pressure treatment. Western species of wood don’t absorb preservative chemicals as easily as some woods and require incising so that enough of the preservative enters the wood.

Included Sapwood

Areas of light-colored wood, apparently sapwood, found within the portion of stem that has becomes heartwood.

Increment Borer

A tool used to take a small core from the bole of a tree to determine growth rate.



Industrial (IND)

A term for lumber destined for remanufacture such as industrial clears, moulding stock and shop.


One who logs and sells his output on the open market; not associated with a mill or under a company/dealer contract.

Industrial Wood

All round wood products excluding fuel wood.


The direction a work piece is fed into a blade or cutter.


Covers the practice of inletting any one material into another material of different color or composition.

Inorganic-Bonded Composites

Manufactured wood-based composites where an inorganic binder, typically gypsum or magnesia-cement, acts as a continuous matrix and fully encapsulates the wood elements.

Internal Stresses

Stresses that exist within an adhesive joint even in the absence of applied external forces.


In wood bonding, a region of finite thickness as a gradient between the bulk adherent and bulk adhesive in which the adhesive penetrates and alters the adherents properties and in which the presence of the adherent influences the chemical and/or physical properties of the adhesive.


To expand with heat to provide a low-density film; used in reference to certain fire-retardant coatings.


An exotic hardwood of South America; renowned for its attractive color, density and rigidity.

  • Olive-brown heartwood
  • Straight to irregular grain
  • Low to medium luster
  • Very high strength
  • Resistant to wood bending
  • Difficult to work with
  • Ideal for bridge building, naval construction, decking, exterior construction, factory flooring, tool handles, archery bows, walking sticks and fishing rods.

An area of a deck that has been cut out to accommodate landscape elements such as trees.


This process uses separate inlays of wood, ivory, bone, brass, silver, etc., cut to shape, laid on the ground, the outlines traced with a fine point and the appropriate recesses cut in with wood-craving tools.

Integrated Logging

Logging operation that segregates and delivers a variety of products to mills and processors that will use them to their greatest potential.

Intensive Forest Management

Utilization of a wide variety of silvicultural practices, such as planting, thinning, fertilization, harvesting, and genetic improvement to increase the capability of the forest to produce fiber.

Intergrown Knot

One partially or completely Intergrown on one or two faces with the growth rings of the surrounding wood.

Interim Forest

A forest that exists or will exist until conversion to a target forest is complete. An interim forest may develop under intensive forest management and may be excellent stocking, but it does not necessarily represent the forest desired at some future time. This is also known as transition forest.

Interlocking Yarder

Device that allows the main and haul-back drums to be operated together as a single unit to maintain running line tension.

Intermediate Support Spar tree or cable sling located between the head spar and tail spar to which a tree jack is attached to support a multispan skyline.
Intermediate Trees

Trees with small, crowded crowns below, but extending into the general canopy level; these trees receive little light from above and none from the side.

International Log Rule

A formula rule that allows a 1/2 inch taper from each 4 feet of length and allows for 1/16-inch shrinkage for each inch of board thickness. This rule is used by the USDA Forest Service.

International 1/4-inch Scale

A log scale modification of an earlier rule using a 1/8-inch kerf, based on an analysis of the loss of wood fiber incurred in the conversion of saw logs to lumber. This is one of the few rules that incorporates a basis for dealing with log taper.


A tree relatively incapable of developing and growing normally in the shade of, and in competition with, other trees.

  • Golden-orange to brown in color
  • Interlocked grain
  • Rather coarse texture, but even
  • Medium density
  • Medium bending and crushing strength
  • Very low stiffness
  • Resistance to shock loads
  • Works satisfactorily with hand and machine tools
  • Used for ship and boat building, laboratory benches, furniture, and domestic flooring.

Exhibiting the same properties in all directions.


Idaho White Pine

Woodipedia Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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