Wood and Metal Construction: From Raw Materials to Structural Systems

Comprehensive vocabulary flashcards covering wood anatomy, sustainable logging practices, light wood framing, mass timber systems, metallurgy, steel manufacturing, and structural steel erection.

Tree Trunk Growth Layers

The concentric biological sections of a tree trunk: the protective outer bark, the cambium (active layer producing new cell growth), the sapwood (living outer rings where nutrients and water are stored and transported to leaves), the heartwood (dead, hardened inner sapwood providing primary structural support), and the central pith.

Wood Warping Defects

Distortions resulting from uneven shrinkage as moisture evaporates during drying, classified into five standard forms: bow (curvature along the wide face), crook (curvature along the narrow edge), kink (a localized angular bend along the edge), cup (transverse curving across the width), and twist (spiral rotational distortion across corners).

Birdsmouth Cut

An angled notch cut into the underside of an inclined rafter to create a flat, horizontal bearing seat that transfers gravity roof loads directly onto the wall's double top plate.

Castellated Beam

A structural steel beam made by flame-cutting the web of a hot-rolled wide-flange section in a continuous zig-zag or hexagonal pattern, separating the two halves, and re-welding them crest-to-crest to increase the overall beam depth and bending strength without adding weight.

Feller Buncher

A mechanized logging vehicle that cuts, trims, and bundles trees on-site; it requires clear-cutting for equipment access and often harvests younger trees before maturity, resulting in weaker lumber.

Selective Logging

A sustainable harvesting method that removes older or dying trees while leaving healthy younger trees, seedlings, and root networks intact to preserve habitat and forest biodiversity.

Rapidly Renewable Materials

Agricultural and plant-derived building materials that grow and replenish within a harvest cycle of $10$ years or less, such as bamboo, cork, wool, and linoleum.

Agri-fiber Boards

Bio-based composite panels and boards manufactured from compressed agricultural crop wastes such as wheat, straw, rice husks, and coconut husks.

Design for Disassembly

An architectural detailing strategy that employs standard member sizes and mechanical fasteners (such as bolts and screws) instead of chemical adhesives, enabling structural elements to be salvaged and reused intact after building demolition.

Plain-Sawn Lumber

A lumber milling method cutting tangentially across growth rings that yields the maximum quantity of usable boards with minimal waste, but produces wide grain patterns prone to warping and cupping; commonly used for light framing.

Quarter-Sawn Lumber

A lumber conversion pattern cut roughly perpendicular to growth rings, generating straight, uniform vertical grain with reduced shrinkage and distortion at the expense of greater milling waste; favored for finish work and cabinetry.

Bookmatching

A woodworking technique where consecutively cut quarter-sawn boards or veneers are arranged edge-to-edge so their adjacent mirror-image grain figures match like an open book.

Nominal vs. Actual Lumber Dimensions

The standard reduction in lumber dimensions caused by planing and seasoning shrinkage: a nominal member loses $1/2''$ off dimensions up to $6''$ (e.g., a $2 \times 4$ measures $1\frac{1}{2}'' \times 3\frac{1}{2}''$) and $3/4''$ off dimensions greater than $6''$ (e.g., a $2 \times 8$ measures $1\frac{1}{2}'' \times 7\frac{1}{4}''$).

Lumber Seasoning

The controlled process of drying freshly sawn green lumber to a moisture content of less than $19\%$ using outdoor air stacking or heated kilns to minimize future shrinkage, checking, and fungal decay.

Softwood

Lumber harvested from coniferous evergreen trees with needles (such as pine, spruce, fir, and cedar); characterized by fast growth, lower density, and straight grains, making it the primary wood for structural light framing.

Hardwood

Lumber harvested from deciduous broad-leafed trees (such as oak, maple, birch, ash, and walnut) that shed their leaves annually; denser, slower-growing, and stronger, making it ideal for interior finishes and furniture.

Pressure-Treated Wood

Softwood lumber impregnated with copper-based chemical preservatives under elevated pressure to protect against insect attacks and fungal rot in exterior, ground-contact, or exposed environments.

Thermally Modified Wood

Wood baked at high temperatures within an oxygen-deprived atmosphere to chemically transform cell-wall sugars and structure, eliminating nutrients for fungi and significantly improving moisture stability for exterior applications.

Balloon Framing

An early nineteenth-century framing system using continuous, multi-story wall studs that extend uninterrupted from the foundation sill to the roof rafters, with intermediate floor platforms suspended from interior ribbon boards.

Platform Framing

A light wood construction method where each story's wall studs rest directly on a subfloor platform erected on top of the story below, inherently providing horizontal fire stops between floor levels.

Chimney Effect

A severe fire hazard associated with balloon framing, in which continuous, hollow wall cavities between studs act as vertical flues that draw fire, heated gases, and smoke upward from floor to floor.

Sill Plate

A horizontal, pressure-treated framing member bolted directly to the top of a concrete or masonry foundation wall using cast-in anchor bolts, providing a level base for floor joists and studs.

Bridging

Diagonal cross-bracing or solid wood blocking installed at mid-span between floor joists to hold them vertical, prevent torsional buckling, and distribute concentrated floor loads across adjacent joists.

Double Top Plate

Two continuous horizontal framing members nailed to the tops of wall studs that overlap at wall corners and intersections, tying the structure together and distributing loads from rafters or joists located off-stud.

Jack Stud (Trimmer)

A shortened vertical framing member fastened against a king stud on either side of a window or door opening to provide direct vertical bearing for the header.

King Stud

A full-length vertical stud extending from sole plate to top plate placed adjacent to a jack stud to brace an opening and secure the ends of the header.

Cripple Stud

Short, non-continuous vertical framing members placed on standard $16''$ or $24''$ centers above a window or door header, or below a window rough sill.

Advanced Framing

An engineered light wood framing technique (also called Optimum Value Engineering) that spaces studs and joists at $24''\text{ o.c.}$ and uses two-stud corners and single top plates to reduce lumber consumption while maximizing thermal cavity insulation.

Collar Tie

A horizontal framing member installed in the upper third of opposing roof rafters to resist wind-induced suction and uplift forces that pull rafters away from the ridge board.

Rafter Tie

A horizontal framing member (often doubling as a ceiling joist) installed in the lower third of a roof structure to tie bottom rafter feet together and counteract outward horizontal thrust under gravity loads.

Structural Sheathing

Plywood or oriented strand board (OSB) panels fastened across wall studs, floor joists, or roof rafters to impart lateral diaphragm and shear-wall rigidity against wind and seismic loads.

Wattle and Daub

A traditional historic wall infill material consisting of a woven wooden lattice of thin branches or split laths (wattle) packed and coated with an adhesive composite plaster of clay, wet soil, and straw (daub).

Char Layer

A dense, low-conductivity layer of carbonized wood that forms at an predictable rate on the exterior of heavy timber or mass timber members during a fire, insulating the interior unburnt core so it maintains load-bearing capacity.

Laminated Veneer Lumber (LVL)

An engineered wood beam manufactured by bonding multiple thin, peeled wood veneers together under heat and pressure with water-resistant adhesives, oriented with their grain running parallel in the longitudinal direction.

Wood I-Joist

An engineered flexural member featuring solid sawn or LVL top and bottom flanges bonded to a thin vertical web of oriented strand board (OSB) or plywood, providing high bending efficiency over longer spans.

Flitch Beam

A composite structural beam built by bolting a vertical structural steel plate between two dimensional lumber or engineered wood members to provide high bending strength within a compact cross-section that accepts nails.

Glue-Laminated Timber (Glulam)

A mass timber product created by stacking and face-bonding individual pieces of dimensional lumber with high-strength synthetic adhesives, capable of being produced in straight, arched, or curved configurations.

Nail-Laminated Timber (NLT)

A solid mass timber panel constructed by placing dimensional lumber boards on edge side-by-side and fastening them together with repetitive rows of nails, functioning primarily in one-way flexural spans.

Cross-Laminated Timber (CLT)

A prefabricated mass timber panel composed of multiple odd-numbered layers of solid-sawn boards glued together at right angles ($90^\circ$), yielding dimensional stability and two-way structural load-bearing capacity for floors, walls, and roofs.

Spline Connection

A joint detail used to connect adjacent CLT floor or roof panels consisting of a continuous strip of plywood or structural composite lumber set into machined edge grooves and secured with long self-tapping screws.

Free Plan

An architectural principle pioneered through skeleton steel framing, where columns replace load-bearing exterior and interior walls to liberate floor space and enable flexible partitions and open spatial layouts.

Ferrous Metals

Metals containing iron as their primary constituent (such as structural steel, cast iron, and wrought iron); notable for high tensile and compressive strength, magnetic behavior, and susceptibility to rust upon oxidation.

Non-Ferrous Metals

Metals that do not contain iron (including aluminum, copper, zinc, brass, bronze, and lead); non-magnetic, relatively malleable, and naturally corrosion-resistant, but typically possessing higher material costs.

Galvanic Corrosion

An electrochemical degradation that occurs when two dissimilar metals are joined in physical contact in the presence of an electrolyte (moisture), causing the more anodic metal to corrode preferentially.

Anode

The more chemically active metal in a galvanic couple (such as zinc or aluminum) that oxidizes and deteriorates while releasing electrons to protect the more cathodic metal.

Cathode

The more noble or passive metal in a galvanic couple (such as copper or stainless steel) that attracts electrical current through an electrolyte and resists corrosion at the expense of the anode.

Smelting

The thermal metallurgical extraction process that heats raw mined ore with reducing agents inside a blast furnace to melt and separate purified metal from gangue and impurities (slag).

Bessemer Process

A historic industrial method for mass-producing steel by blowing air through molten pig iron in an open converter to rapidly burn out impurities such as carbon, silicon, and manganese via oxidation.

Hot-Rolled Steel

Structural steel shapes formed by heating blooms above their recrystallization temperature and feeding them through high-pressure roller stands into profiles like wide-flange I-beams, channels, and angles.

Cold-Formed Steel

Structural steel framing members and decking manufactured by feeding cold, thin sheets of galvanized steel through roll-forming dies at ambient temperatures.

Extrusion

A manufacturing method where a heated billet of ductile metal (most commonly aluminum) is forced by a mechanical ram through a hardened die opening matching the desired cross-sectional profile.

Drawing

A metal-forming process where metal stock is pulled in tension through tapered dies to reduce its diameter and increase its length, producing wires, rods, and seamless tubing.

Intumescent Coating

A specialized thin-film fireproofing paint applied to exposed structural steel that expands under high temperatures into a thick, multicellular insulating char barrier, maintaining fire ratings without concealing the steel shape.

Primary Structure

The principal skeletal framework in a multi-tier structural system, comprised of major vertical columns and horizontal girders typically configured on $25'$ to $35'$ bay spacings.

Secondary Structure

Intermediate structural framing elements (such as open-web bar joists, beams, or purlins) spaced at $3'$ to $6'\text{ o.c.}$ to span between primary girders and support surface decking.

Tertiary Structure

The continuous planar deck layer (such as corrugated metal roof or floor decking) that spans across secondary joists to support live and dead floor or roof loads.

Base Plate

A thick, square or rectangular steel plate shop-welded to the bottom of a steel column to distribute heavy, concentrated vertical column loads over a larger area of concrete footing and receive foundation anchor bolts.

Web Stiffener

A vertical steel plate welded between the flanges of an I-beam or plate girder to reinforce the thin web against crippling and shear buckling directly beneath heavy point loads or over column supports.

Plate Girder

A large, custom I-shaped structural beam constructed by shop-welding individual thick steel plates for the top flange, bottom flange, and vertical web to span distances exceeding standard rolled sections.

Open-Web Steel Joist (Bar Joist)

A lightweight, prefabricated shop-manufactured steel truss built of angle-iron top and bottom chords separated by a zig-zagging bent steel bar web, featuring an open web profile that accommodates MEP utilities.

Purlin

A secondary cold-formed channel, Z-section, or small beam spanning horizontally across primary roof rafters or trusses to directly support roof decking panels.

Composite Metal Decking

Corrugated sheet steel decking detailed with embossed indentations or rib patterns that mechanically interlocks with a cast-in-place concrete topping slab, combining steel tension strength with concrete compressive resistance.

Shear Connector (Shear Stud)

A headed round steel rod welded through corrugated metal decking directly onto the top flange of a steel beam, creating mechanical shear transfer between the cured concrete floor slab and the supporting steel member.

Topping Out

A traditional structural ironworking ceremony tracing back to an ancient Scandinavian rite of placing a small evergreen tree atop the highest structural member of a newly framed building to appease displaced woodland spirits.

Light-Gauge Steel Framing

A cold-formed structural assembly made from thin galvanized sheet steel bent into C-shaped studs and joists that slide into horizontal U-shaped runner tracks, secured together with self-tapping screws.