Facade

• Air barrier

  A continuous layer of materials, tapes, and sealed joints that stops uncontrolled air from leaking into or out of a building.

• Base course

  A base course is the lowest horizontal row of masonry, such as stone, brick, or concrete blocks, located at the foundation level of a building's exterior wall. It serves both functional and aesthetic purposes by providing a sturdy, level starting point for the rest of the wall construction and often acting as a visual transition between the ground and the upper structure. Depending on the design, the base course may be thickened or reinforced to help distribute the structural load and protect the building from ground-level moisture and physical wear.

• Belt course

  A belt course, also known as a string course, is a continuous horizontal band of masonry or other material that projects from or is set into the exterior wall of a building. Typically used to visually mark the division between different stories or to align with architectural features like window sills or headers, it serves to break up the vertical expanse of a facade and provide rhythmic definition to the structure's design. Beyond its decorative role in defining a building's scale and proportion, a belt course can also function as a water table to help shed rainwater away from the wall surface below.

• Cladding

  Cladding is a non-loadbearing architectural element applied as an exterior skin or layer over a building's primary structure to provide protection, insulation, and aesthetic enhancement. Functioning as the building's first line of defense, it shields the underlying frame from environmental elements such as rain, wind, UV radiation, and temperature fluctuations, while often incorporating thermal and acoustic insulation to improve energy efficiency and interior comfort. Available in a diverse range of materials—including timber, stone, brick, metal, glass, fiber cement, and composites—cladding allows architects to define a structure's visual identity through various textures, colors, and patterns without adding significant structural weight. Depending on the design, systems like rainscreens can be utilized to manage moisture infiltration and airflow, ensuring the long-term durability and integrity of the building envelope.

• Clerestory

  An upper wall containing a band of windows above adjacent roofs or above eye level, bringing daylight deep into an interior.

• Control joint

  A control joint is a continuous groove or planned break integrated into an exterior wall or cladding system to manage the effects of material expansion and contraction. By providing a predetermined path for movement caused by temperature fluctuations or moisture changes, these joints encourage cracking to occur in a neat, controlled line rather than randomly across the facade. This intentional structural detail helps maintain the aesthetic and functional integrity of the building envelope, preventing unsightly damage and potential water infiltration.

• Cornice

  A projecting horizontal moulding that crowns a wall, building, or architectural composition. In the classical entablature, the cornice is the uppermost of its three principal divisions.

• Curtain wall

  A lightweight outer wall, usually of glass and aluminum, hung from the building’s structural frame. It carries only its own weight and wind pressure while keeping weather out.

• Expansion joint

  An expansion joint is a critical structural gap designed to safely absorb the heat-induced expansion and contraction of various construction materials, as well as to accommodate vibration and allow for soil settlement or seismic movement. By providing a dedicated space for these inevitable shifts, it prevents the buildup of internal stress that could otherwise lead to cracking, buckling, or structural failure in walls, floors, and facades. These joints are typically filled with flexible, weather-resistant sealants or specialized assemblies to maintain the integrity of the building envelope while ensuring the long-term durability of the assembly.

• Exterior insulation

  Exterior insulation is a non-structural layer of thermal material applied to the outer surface of a building's envelope to improve energy efficiency and thermal performance. By placing the insulation outside the structural walls, it creates a continuous thermal barrier that minimizes thermal bridging and protects the building's structure from extreme temperature fluctuations. This system is typically integrated with a weather-resistant barrier and finished with cladding or a decorative coating, such as an exterior insulation and finish system (EIFS), to provide both protection from the elements and a finished aesthetic appearance.

• Facade

  A facade is the exterior face or wall of a building, typically the one facing a street or open space, that defines its architectural character and aesthetic identity. It serves both functional and decorative purposes, acting as a protective skin against environmental elements while incorporating features such as windows, doors, and ornamentation to communicate the building's style and relationship to its surroundings.

• Mullion

  A vertical element that divides adjacent window units or panes. Its horizontal counterpart is the transom.

• Parapet

  A low wall extending above the edge of a roof, terrace, balcony, or bridge, serving as a barrier and as the termination of the facade.

• Pier

  A pier is a solid, upright structural element used to support vertical loads from arches, vaults, or bridge spans. Unlike a column, it is typically more massive and square or rectangular in cross-section, though it can also be thickened sections of a wall designed to provide additional strength at points of concentrated stress. Piers are essential in traditional masonry construction, where they function as heavy-duty vertical supports that transfer the weight of the structure to the ground.

• Pilaster

  A shallow rectangular projection from a wall, detailed like a flattened column with a base, shaft, and capital. Pilasters articulate a facade and often follow the proportions of a classical order.

• Quoin

  The external angle of a wall, or one of the large, often emphasized blocks forming that corner in masonry construction.

• Rainscreen

  A wall assembly in which an outer cladding sheds most rain, backed by a ventilated air gap and a weather barrier that drains away any water that gets past.

• Reveal

  A reveal is a recessed or set-back portion of a wall surface, often used as a decorative feature to create visual depth and shadow lines on a building's facade. In architectural detailing, it frequently refers to the side of an opening for a window or door that is not covered by the frame, or a continuous groove used to articulate the transition between different materials or planes. These elements serve to define architectural edges, hide joints, and provide a clean, modern aesthetic by emphasizing the geometry and layered composition of the building envelope.

• Rustication

  A treatment of masonry with deeply recessed joints and often roughened faces, commonly used on lower storeys to give an impression of weight and strength.

• Sheathing

  Sheathing refers to the protective outer layer of boards or panels, typically made of engineered wood like plywood or oriented strand board (OSB), that is fastened to the structural framing of a building's walls, floors, or roof. It serves as a vital structural component by tying framing members together to increase shear strength and provide a stable, uniform nailing base for exterior finishes such as siding, shingles, or masonry veneer. Beyond its structural role, sheathing acts as a secondary barrier against the elements, helping to insulate the structure and protect the interior framework from moisture and wind infiltration. Depending on the application and material used, sheathing can be classified as structural, providing rigidity and load distribution, or non-structural, primarily offering thermal insulation and weather resistance.

• Siding

  Siding is the protective exterior cladding or covering attached to the walls of a house or building, serving as the first line of defense against environmental elements like sun, rain, snow, and extreme temperatures. It functions both practically to prevent heat loss and moisture infiltration and aesthetically to define a structure's architectural character and curb appeal. Typically composed of smaller, weather-resistant units like shingles, boards, or panels to allow for thermal expansion, siding is available in various materials including wood, vinyl, metal, fiber cement, and masonry.

• Sill

  The horizontal member at the base of a window or door opening, shaped to shed water away from the wall below.

• Soffit

  The finished underside of an architectural element, such as an arch, beam, balcony, stair, or roof overhang.

• String course

  A string course is a continuous horizontal band, typically made of brick or stone, that projects from the exterior wall of a building. It serves both decorative and functional purposes, often used to visually divide different stories of a structure or to delineate changes in materials and architectural features. Beyond its aesthetic contribution to the facade's rhythm and scale, a string course can also act as a weather-shielding element, helping to deflect rainwater away from the wall surface below.

• Thermal break

  A low-conductivity material placed inside an assembly, such as a window frame or balcony connection, to stop heat flowing straight through between inside and outside.

• Transom

  A horizontal bar dividing a window into tiers or separating a door from a window above; also the window above the door itself.

• Vapor barrier

  A layer that slows water vapor from passing through walls, roofs, and floors, rated by its permeance.

• Water table

  A water table is a horizontal architectural projection or offset near the base of an exterior wall, designed to direct rainwater away from the building's foundation. Frequently constructed of masonry, stone, or sloped wood, it serves the functional purpose of preventing moisture from seeping into the lower structure while also providing a visual transition between the foundation and the upper wall. This feature often marks a change in material or thickness, enhancing the building's aesthetic by defining its base with a distinct, protective ledge.

• Weather barrier

  A weather barrier is a system of materials designed to prevent the infiltration of liquid water and wind into a building's structural components. Typically installed behind the exterior cladding, it serves as a secondary line of defense that protects the sheathing and framing from moisture damage, rot, and mold. By effectively managing water drainage and reducing air leakage, weather barriers enhance the overall durability and energy efficiency of the building envelope.