If you’re planning an extension, loft conversion or renovation, you’ll soon hear plenty of technical terms. Here’s a simple guide to the most common ones.
Planning & Project Team
Architect – Registered with the Architects Registration Board (ARB).
Planning consultant – Planning specialist for complex applications.
Planning – Council permission for some developments.
Permitted Development (PD) – Work that may not require planning permission; we usually recommend obtaining a Lawful Development Certificate (LDC).
Conservation area – Protected area where planning controls are stricter and PD rights may be restricted.
Party wall – Shared wall or boundary that may require notice to adjoining neighbours.
Building Regulations (Building Regs) – Standards covering safety, structure, insulation, drainage and energy efficiency.
SAP calculations – Energy assessment required for Building Regulations compliance.
Structural engineer – Designs structural elements such as beams and foundations.
Quantity surveyor – Estimates and manages construction costs.
Principal designer – Oversees health and safety during the design stage under CDM Regulations.
Builder / Principal Contractor – Usually the same person on domestic projects; builds and manages the construction phase safely.
Building inspector – Checks the work complies with Building Regulations.
Reading Drawings
Plan – A view from above.
Elevation – An outside view of the building.
Section – A cut-through drawing showing the building’s construction.
Roofs & Extensions
Hipped roof – Roof sloping on all sides.
Gable – Triangular wall at the end of a pitched roof.
Dual pitch – Roof with two sloping sides.
Monopitch – Roof with one continuous slope.
Dormer – Roof projection with a window that increases loft headroom.
Flat roof – Nearly level roof designed with a slight fall for drainage.
Parapet – Wall extending above the edge of a roof.
Ridge – Highest point where roof slopes meet.
Eaves – Lower edge of a roof where rainwater drains into the gutter.
Lantern – Raised glazed roof structure that brings daylight into a room.
Rooflight – Window built into the roof.
Green roof – Roof covered with planting to improve biodiversity and insulation.
Brise soleil – External architectural shading that reduces overheating.
Construction & Services
Soil vent pipe – Vertical pipe that vents the foul drainage system.
Soakaway – Underground drainage system that allows rainwater to soak into the ground.
DPC (Damp-proof course) – Layer that prevents rising damp in walls.
Trickle vents – Small vents built into window frames to provide background ventilation.
Escape windows – Windows large enough to provide an emergency escape route.
Radon – Naturally occurring ground gas that requires protective measures in some parts of the UK.
Stairs
Kite winder – Tapered stair used to turn a staircase.
Riser – Vertical height of a stair.
Going – Horizontal depth of a stair tread.
Understanding these terms will help you communicate more confidently with your architect, builder and the rest of your project team. Good design isn’t just about drawings—it’s also about making sure you understand every stage of the journey.
