Construction terms, plainly defined
Clear definitions of the construction, estimating, and building-code terms contractors and homeowners run into — each one short, accurate, and linked to where it matters.
AFCI (arc-fault circuit interrupter)
An arc-fault circuit interrupter (AFCI) is a protective device that detects dangerous electrical arcing and shuts off the circuit to prevent fires.
GFCI (ground-fault circuit interrupter)
A ground-fault circuit interrupter (GFCI) is a device that cuts power within milliseconds when it detects current leaking to ground, protecting people from electric shock.
Egress / EERO (emergency escape and rescue opening)
An emergency escape and rescue opening (EERO) is a window or door large enough to escape through and for a firefighter to enter — required in every sleeping room.
AHJ (authority having jurisdiction)
The authority having jurisdiction (AHJ) is the local agency or official — usually the building department — that adopts, interprets, and enforces the code where you build.
Takeoff (quantity takeoff)
A takeoff is the process of measuring and counting the materials and quantities needed for a project directly from the drawings — the basis of an estimate.
Overhead and profit (O&P)
Overhead and profit (O&P) is the markup added to the direct cost of a job to cover a contractor's business costs (overhead) and earnings (profit).
Basis of estimate (BOE)
A basis of estimate (BOE) is the documented set of assumptions, inclusions, exclusions, and data sources behind an estimate — the 'show your work' for a number.
AACE estimate class
AACE estimate classes (Class 5 to Class 1) describe how mature and accurate an estimate is, based on how complete the project's design is.
RFI (request for information)
A request for information (RFI) is a formal question from the contractor to the design team to clarify or resolve something unclear in the drawings or specifications.
Submittal
A submittal is the documentation a contractor provides — product data, shop drawings, samples — for the design team to review against the specifications before installation.
Change order
A change order is a written, signed agreement that modifies the contract's scope, price, or schedule after work has begun.
Punch list
A punch list is the list of remaining or deficient items a contractor must complete or correct before a project is considered finished.
CPM schedule (critical path method)
A critical path method (CPM) schedule is a project timeline that maps task dependencies to compute the longest chain of work — the 'critical path' that drives the finish date.
Earned value management (EVM)
Earned value management (EVM) is a method that combines scope, schedule, and cost to measure whether a project is ahead or behind and over or under budget — with objective indices.
Lien waiver
A lien waiver is a signed document in which a contractor, subcontractor, or supplier gives up their right to file a mechanic's lien for payment they have received.
Pay application (pay app / draw)
A pay application (or 'draw') is a contractor's formal request for a progress payment, showing the work completed to date against the schedule of values.
R-value
R-value measures how well insulation resists heat flow — the higher the R-value, the better the insulating performance.
Load-bearing wall
A load-bearing wall is a wall that carries structural weight from above — floors, the roof, or other walls — down to the foundation.
Setback (zoning)
A setback is the minimum distance a building must be kept from property lines, streets, or other features, set by local zoning rules.
Certificate of occupancy (CO)
A certificate of occupancy (CO) is the document a building department issues confirming a structure complies with code and is safe to occupy for its intended use.
Joist
A joist is one of a series of parallel horizontal members that support a floor or ceiling, spanning between beams, walls, or foundations.
Rafter
A rafter is a sloped structural roof member that runs from the ridge down to the exterior wall, supporting the roof sheathing and covering.
Header (framing)
A header is a beam placed across the top of a door, window, or other opening to carry the loads from above and transfer them to the framing on each side.
Footing
A footing is the widened base of a foundation that spreads a structure's load over the soil, keeping the building from settling or sinking.
Soffit
A soffit is the finished underside of a roof overhang (the eave) — the horizontal surface that closes off the space beneath the edge of the roof.
Fascia
Fascia is the vertical band that runs along the edge of a roof, capping the ends of the rafters or trusses and creating the surface that gutters attach to.
Flashing
Flashing is thin, water-resistant material — usually metal — installed at joints, transitions, and penetrations to direct water away and keep it out of the building.
Vapor barrier (vapor retarder)
A vapor barrier (more accurately a vapor retarder) is a material that limits how much water vapor diffuses through a wall, floor, or ceiling assembly, helping control condensation.
OSB (oriented strand board)
Oriented strand board (OSB) is an engineered wood panel made of compressed wood strands bonded with adhesive, used widely as sheathing and subfloor.