ARCH 170: Wood & Light Gauge Steel Construction

Vocabulary practice flashcards covering wood anatomy, conversion, light frame and heavy timber construction, mass timber, and light gauge steel framing from the ARCH 170 Midterm Review.

Kalambo Falls Wooden Structure

The oldest known wooden structure discovered on the border of Zambia and Tanzania, dating to approximately $500{,}000\text{ years}$ old and predating modern humans by $125{,}000\text{ years}$.

Primitive Hut

An architectural concept articulated by Marc-Antoine Laugier in $1755$ asserting that architecture derived directly from nature and served as the fundamental inspiration for classical architecture.

Cruck Frame

An early timber framing form evolved from covered pit dwellings that utilizes pairs of large curved timbers (crucks) to transfer roof loads directly to the ground or low foundation.

Balloon Frame

A 19th-century North American light-frame system developed in the $1880\text{s}$ utilizing continuous, slender studs that span uninterrupted from the ground floor sill to the roof, facilitated by industrial sawmills, machine-made nails, and rail transport.

Platform Frame

A post-WWII light wood framing method (also called Western framing) where wall studs are only one story high and each level is built as a complete horizontal platform that supports the story above.

Softwood

Lumber harvested from coniferous (evergreen) trees that is fast-growing with an open, knotty grain, primarily used for structural framing (e.g., pine).

Hardwood

Lumber harvested from deciduous (broadleaf) trees that is slower-growing with a tighter grain, primarily utilized for finished applications, flooring, and cabinetry (e.g., oak).

Cambium

The thin living layer of cells between the bark and wood of a tree responsible for generating new sapwood and inner bark during secondary growth.

Wood Cell Orientation

The vertical alignment of tree cells designed to transport water and sap from roots to leaves, which establishes the direction of the wood grain.

Plainsawn Lumber

Lumber sawn such that annual growth rings run roughly parallel to the wider board face, maximizing yield from the log.

Quartersawn Lumber

Lumber produced by quartering the log and cutting radially so that annual growth rings intersect the board face at approximately perpendicular ($90^\circ$) angles, producing greater dimensional stability.

Nominal vs. Actual Lumber Dimensions

The commercial size designation versus actual dressed size: nominal dimensions from $2\text{ in.}$ through $6\text{ in.}$ lose $1/2\text{ in.}$ (e.g., a nominal $2 \times 4$ is actually $1\frac{1}{2}" \times 3\frac{1}{2}"$), while dimensions above $6\text{ in.}$ lose $3/4\text{ in.}$ (e.g., nominal $2 \times 10$ is actually $1\frac{1}{2}" \times 9\frac{1}{4}"$).

Wood Seasoning

The process of reducing moisture content in lumber via air drying or kiln drying to increase strength, resist biological decay, and control distortion caused by grain shrinkage.

Glulam (Glue-Laminated Timber)

An engineered structural wood product made by bonding individual pieces of solid lumber together with moisture-resistant adhesives, allowing for longer spans, higher load capacity, and curved profiles.

Cross-Laminated Timber (CLT)

An engineered mass timber panel manufactured by stacking and gluing dimensional lumber boards in alternating perpendicular layers, creating high-strength structural wall and floor slabs.

Structural Composite Lumber (SCL)

A family of engineered wood products manufactured by gluing together wood veneers or strands; includes non-structural Oriented Strand Lumber (OSL), Parallel Strand Lumber (PSL), and full-depth Laminated Veneer Lumber (LVL).

Wood I-Joist

An engineered composite framing beam consisting of top and bottom solid lumber or LVL flanges connected by a vertical web made of OSB or plywood, designed for long floor and roof spans.

Oriented Strand Board (OSB)

A structural engineered wood panel made from compressed wood strands aligned in cross-oriented layers and bonded with resin, commonly used for subflooring and exterior sheathing.

Truss Plate

A light-gauge galvanized steel plate with integral punched metal teeth, hydraulically pressed into lumber faces to join members in prefabricated roof and floor trusses.

Framing Module

The standard $4\text{'-}0"$ layout system in platform construction based on $16\text{ in.}$ (3 spaces) or $24\text{ in.}$ (2 spaces) on-center spacing to accommodate standard $4\text{ ft} \times 8\text{ ft}$ panel sheathing.

Advanced Framing

A wood framing technique utilizing $24\text{ in.}$ on-center stud spacing to reduce timber consumption and increase wall cavity volume for insulation while accepting minor structural trade-offs.

Sill Plate (Mud Sill)

The preservative-treated horizontal framing member anchored directly to the foundation wall that forms the base support for floor joists and studs.

Sheathing

Panels (typically OSB or plywood) attached to the exterior faces of wall studs or rafters that act as a structural diaphragm against lateral loads and form part of the building's control layer against air/vapor infiltration.

Framing Plan vs. Floor Plan

A floor plan indicates locations and dimensions of finished walls, partitions, and openings; a framing plan specifically shows the sizes, layouts, and spacing of structural joists and rafters.

Header

A heavy horizontal framing member installed across the top of a door or window rough opening to transfer vertical gravity loads to flanking trimmer studs.

Trimmer Stud (Jack Stud)

A shortened vertical framing member fitted tight beneath each end of a header to carry header loads down to the sole plate.

King Stud

A full-height vertical wall stud fastened directly alongside a trimmer stud, spanning continuously from the bottom plate to the double top plate.

Cripple Stud

A non-full-height framing member placed above a header (top cripple) or below a window sill (bottom cripple) to maintain standard framing spacing.

Roof Hip

The inclined projecting exterior angle formed by the intersection of two adjacent sloping roof planes.

Roof Valley

The internal inclined intersection line formed where two sloping roof surfaces meet, toward which runoff rainwater flows.

Roof Gable

The triangular vertical portion of an exterior end wall enclosed between the eaves and the ridge of a pitched roof.

Dormer

A vertical projecting structure built outward from a sloping roof plane housing a window or ventilation louver.

Eave and Soffit

The eave is the overhanging lower projecting edge of a sloping roof; the soffit is the exposed underside surface beneath that overhanging eave.

Light Gauge Steel (LGS) Framing

A framing system composed of thin, cold-formed sheet steel whose structural dimensions match nominal $2\text{-inch}$ dimensional wood lumber, offering a noncombustible stick-framing alternative.

C-Stud (Light Gauge Steel)

A cold-formed structural steel section with a vertical web, horizontal flanges, and return lips; available in depths from $1\text{-}5/8"$ to $12\text{ in.}$ and metal thicknesses from $0.018\text{ to }0.097\text{ in.}$ ($18\text{ to }97\text{ mils}$).

Track (Light Gauge Steel)

A U-shaped cold-formed channel fastened along the top and bottom of walls or ends of floors to receive and align C-studs or joists, serving as the steel equivalent of wall plates and rim joists.

Punchouts (LGS)

Factory-perforated web openings spaced at regular intervals (typically $2\text{'-}0"$) along C-studs to permit horizontal routing of plumbing, electrical conduits, and cross-bracing without field drilling.

Thermal Bridging

A significant disadvantage of light gauge steel framing wherein steel members rapidly conduct heat across wall cavities, requiring continuous exterior insulation to prevent heat loss.

Char Layer

The carbonized outer crust that develops when heavy timber is exposed to fire; it acts as a low-conductivity protective insulating blanket that decelerates thermal degradation of the inner wood core.

Mortise and Tenon

A traditional timber joinery method consisting of a peg-secured projecting tongue (tenon) carved on one timber that fits precisely into an internal cavity (mortise) cut into another.

End Grain Weather Protection

Protective copper sheet metal covers installed over exposed exterior timber end grain with an intentional air gap to prevent capillary water absorption and fungal decay.

Fire-Cut Beam End

An angular bevel cut at the seating end of a heavy timber beam embedded in a masonry wall, engineered to allow a failing burning beam to tip out of its pocket without levering or collapsing the exterior masonry wall.

Mass Timber vs. Heavy Timber

Heavy Timber denotes a specific historic framing type and building code classification; Mass Timber denotes a contemporary structural category wherein the building's primary loadbearing frame and floors are made of thick solid or engineered wood panels.

Carbon Sequestration (Forests & Timber)

The capture and storage of carbon in timber; temperate managed forests remove approximately $0.7\text{ tons}$ of carbon per acre per year, allowing mass timber structures to function as carbon-negative alternatives to concrete and steel.