back span: A piece of the cantilever joist or rafter that extends within the supporting wall.

balcony: exterior floor projecting from and supported by a structure without additional independent supports.

ballast: A material similar to aggregate or pavers (smooth river stone, crushed stone, concrete pavers, lightweight concrete pavers, etc.) that is often used as a weight on loose-laid roofing systems to hold the membrane in place.

ballast scouring: A term used to describe the shifting of ballast or loosened pavers on the exposed surface of a roof, usually as the result of wind.

band joist: dimensional lumber used as a perimeter joist of the building framing.

barrel vault: An architectural element that is formed by the extrusion of semi-cylindrical curves. It may appear as a series of arches.

base flashing: The upturned edge of a watertight membrane formed at a roof's termination point by the extension of the felts vertically over the cant strip and up the wall, and secured with mechanical fasteners.

basement: that portion of a building which is partly or completely below grade.

basement wall: a wall of a building that is mostly below grade.

bathroom: a room containing plumbing fixtures, such as a water closet, urinal, bathtub and/or shower.

batten: A general term used to describe a cap or covering. In a singly-ply membrane installation, it’s a narrow bar used to hold the roof membrane and/or base flashing in place.

beam: A horizontally placed primary structural support member (of steel, concrete, lumber, etc.) transversely supporting a load that transfers weight from one location to another. It’s often supported by posts, exterior walls, or foundational elements.

bearing wall: A bearing wall, or a load-bearing wall, is designed to carry the weight of structural components above, through itself, and to the supporting components below.

bedroom: a room used for sleeping purposes.

bidet: a toilet-like plumbing fixture designed to promote posterior hygiene; not a toilet.

billowing: A term used to describe a membrane that is filled or lifted with air and swells outward.

biological contaminants: agents derived from or that are living organisms (e.g., viruses, bacteria, fungi, and mammal and bird antigens) that can be inhaled and can cause many types of health effects including allergic reactions, respiratory disorders, hypersensitivity diseases, and infectious diseases. Also referred to as “microbiologicals” or “microbials.”

bitumen: Any of a variety of mixtures of hydrocarbons occurring naturally or obtained through the distillation of coal or petroleum.

blister: A term used to describe an enclosed raised spot evident on the surface of a roof.

blistering: The process and occurrence of a void or unhindered area between the plies or between the substrate, mainly caused by the expansion of trapped air, water vapor, moisture, or other gases.

blueberry blister: A term used to describe a small raised spot on the roof covering’s surface, which forms when liquid or vapor is trapped in asphalt in a BUR system.

bonding: the permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity, and the capacity to conduct safely any fault current likely to be imposed.

boot: A flexible material or metal that is used as flashing.

branch circuit: the circuit conductors between the final over-current device protecting the circuit and the outlet(s).

breathing zone: area of a room in which occupants breathe as they stand, sit, or lie down.

BRI: Building-Related Illness.

building: the primary building subject of the commercial inspection.

building code: rules and regulations adopted by the governmental authority having jurisdiction over the construction and/or remodeling of the commercial property.

building department: local authority having jurisdiction over the construction, alteration and use of a property.

building envelope: the enclosure that defines the heated/cooled area of a building, namely, the exterior walls and roof.

building-related illness: diagnosable illness whose symptoms can be identified and whose cause can be directly attributed to airborne building pollutants (e.g., Legionnaire’s disease, hypersensitivity pneumonitis).

building systems: components, assemblies and systems that are a part of the overall building and property such as pavement, flatwork, structural components, roofing, exterior walls, plumbing, HVAC, electrical components, fire prevention, etc.

built-in: permanently installed.

built-up roofing (BUR): Also called tar-and-gravel roofing, BUR is a roofing system composed of three to five layers of asphalt felt laminated with coal tar, pitch or asphalt, and finished on top with a smooth surface, crushed slag or gravel.

BUR: built-up roofing

buttress: An architectural element and supporting member that is built against or projecting from a wall, often found in gothic-style buildings and barrel vaults.