Blueprint & Floor Plan Terminology Guide

Why terminology matters

Architectural plans use specialized vocabulary that can feel impenetrable if you are not in the industry. Whether you are reviewing plans for a home purchase, discussing a renovation with a contractor, or studying architecture, understanding these terms helps you participate in the conversation with confidence.

This guide covers the most common terms you will encounter in residential and commercial floor plans, organized by category.

Building structure terms

Bearing wall (load-bearing wall)

A wall that supports weight from above — the roof, upper floors, or both. Bearing walls cannot be removed without structural engineering to redistribute the load. On floor plans, they are often drawn with thicker lines than partition walls.

Partition wall

A non-structural wall that divides interior space. Partition walls can generally be moved, shortened, or removed during renovation without affecting structural integrity.

Footprint

The total ground area covered by a building, measured at the foundation level. A building with a 10m x 12m footprint covers 120 square meters of land.

Setback

The minimum distance a building must be placed from a property line, road, or other boundary. Setback requirements are defined by local zoning regulations and vary by jurisdiction.

Foundation

The structural base of a building that transfers loads to the ground. Common types include slab-on-grade (a flat concrete pad), crawl space (raised with access underneath), and full basement.

Measurement terms

Gross floor area (GFA)

The total floor area measured from the exterior face of exterior walls. This includes wall thickness, stairwells, elevator shafts, and mechanical spaces. Gross area is typically what appears in building permits.

Net floor area

The usable area inside a building, excluding walls, columns, mechanical shafts, and circulation spaces. Net area is what you actually live or work in. It is always smaller than gross floor area.

Ceiling height

The vertical distance from the finished floor to the underside of the ceiling. Standard residential ceiling height is 2.4m (8 feet) in most countries. Higher ceilings (2.7m or 3m) create a more spacious feel.

Clear span

The unobstructed distance between supporting elements (walls, columns, or beams). A room with a 6m clear span has no columns or supports within that 6-meter width.

Drawing types

Floor plan

A horizontal cross-section of a building, typically cut at 1.2m (4 feet) above floor level. Shows walls, doors, windows, fixtures, and room layouts from above. This is the most common architectural drawing type.

Elevation

A vertical view of one face of a building, drawn as if you were standing in front of it. Elevations show exterior materials, window positions, roof lines, and vertical proportions. There is typically one elevation for each side — front, rear, left, and right.

Section

A vertical cut through the building, revealing the interior structure. Sections show floor-to-floor heights, roof construction, foundation depth, and the relationship between different levels. They are like slicing the building in half and looking at the cut face.

Site plan

A bird's-eye view of the entire property showing the building footprint, driveways, landscaping, property boundaries, and setback lines. Site plans are drawn at a larger scale than floor plans (often 1:200 or 1:500).

Reflected ceiling plan (RCP)

A floor plan that shows ceiling features — light fixtures, ceiling fans, air vents, and changes in ceiling height — as if you were looking up at the ceiling through a mirror on the floor.

Door and window terms

Egress

A means of exit from a building. Building codes require bedrooms to have at least one egress window large enough for a person to climb through in an emergency. Egress requirements specify minimum width, height, and sill height.

Fenestration

A technical term for all openings in a building envelope — windows, doors, skylights, and curtain walls. Fenestration ratio describes the percentage of wall area occupied by glazing.

Transom

A horizontal window above a door or another window. Transoms add natural light without sacrificing wall space or privacy.

Mullion

A vertical or horizontal bar that divides a window into separate panes. Mullions can be structural (supporting the glass) or decorative (applied to the surface).

Jamb

The vertical side framing of a door or window opening. Door jambs are the surfaces your hinges and strike plate mount to.

Room and space terms

En suite

A bathroom directly connected to and accessible only from a bedroom. An en suite bathroom is private to the bedroom it serves.

Alcove

A recessed area in a room, often used for a bed, desk, or seating area. Alcoves add architectural interest and help define zones within an open room.

Vestibule

A small enclosed entry area between an exterior door and the main interior space. Vestibules act as an airlock to reduce heat loss and provide a transition space for removing outerwear.

Open plan (open concept)

A layout where two or more traditional rooms (typically kitchen, dining, and living) share a single continuous space without dividing walls. Open plans maximize sight lines and create a sense of spaciousness.

Wet room

Any room with plumbing — kitchens, bathrooms, laundry rooms. The term is used in construction planning because wet rooms require waterproofing, drainage, and plumbing rough-ins that dry rooms do not.

Construction abbreviations

You will frequently see abbreviations on architectural drawings. Here are the most common:

• AFF — Above finished floor (a height measurement reference)
• CLG — Ceiling
• CMU — Concrete masonry unit (cinder block)
• CL or CEN — Centerline
• DF — Drinking fountain
• DW — Dishwasher
• EL or ELEV — Elevation
• FFL — Finished floor level
• GYP — Gypsum (drywall)
• HVAC — Heating, ventilation, and air conditioning
• NIC — Not in contract
• NTS — Not to scale
• OC — On center (spacing measurement for studs or joists)
• REF — Refrigerator
• TYP — Typical (this detail repeats in similar locations)
• WH — Water heater

Putting it together

These terms form the shared vocabulary of architectural communication. When you review a set of plans — whether for a home purchase, a renovation, or a design project — recognizing this terminology lets you ask the right questions and understand the answers.

For a visual introduction to floor plan reading, see our Floor Plan Basics guide. If you want to see how flat plans translate into three-dimensional space, try converting a floor plan to 3D with Ritn3D.