A quick glossary of the words builders, architects and surveyors use, translated.
- Permitted development (PD)
- Work you can carry out without a full planning application, within set limits.
- Lawful Development Certificate (LDC)
- An official confirmation that work is lawful under permitted development. Useful proof when you sell.
- Building Regulations
- The rules that govern how a building is constructed, for safety and performance. Signed off by building control.
- RIBA stages
- The Royal Institute of British Architects' plan of work, breaking a project into numbered stages from brief to handover.
- Groundworks and substructure
- Everything below ground and up to floor level: foundations, drainage and slabs. The superstructure is everything above.
- First fix and second fix
- First fix is the work hidden in walls and floors (pipes, cables, framing). Second fix is the visible finishing (sockets, doors, skirting).
- Damp proof course (DPC)
- A barrier built into walls to stop moisture rising up from the ground.
- Screed
- A smooth, level layer laid over a floor, often over underfloor heating, ready for the final finish.
- Steel beam (RSJ)
- A steel support used to carry the load when a wall is removed or a large opening is formed.
- U-value
- A measure of how much heat a building element lets through. Lower is better.
- Fabric first
- The principle of insulating and sealing the building well before adding heating and renewable technology.
- MVHR
- Mechanical ventilation with heat recovery: supplies fresh air while recovering heat from the air it removes.
- Provisional sum
- An allowance in the costs for work that is not yet fully defined, adjusted once the detail is known.
- Prime cost (PC) sum
- An allowance for an item you have not yet chosen, such as tiles or a kitchen, to be selected later.
- Contingency
- Money set aside for the unexpected, usually 10 to 15 per cent, especially on older buildings.
- Variation
- A change to the agreed works during the build, priced and recorded so the budget stays clear.
- Snagging
- The list of small fixes and finishing touches identified near the end of a project.
- Practical completion
- The point at which the work is finished and the home can be used, even if minor snags remain.
- Retention
- A small percentage held back for a period after completion, released once any snags are put right.
- Defects liability period
- A set period after completion during which the builder returns to fix any defects that appear.
- Party wall
- A legal process for work that affects a wall or boundary shared with a neighbour.
- JCT contract
- A standard form of building contract from the Joint Contracts Tribunal, widely used to set out terms fairly.
Everyday site language
And here is the language you will actually hear on a building site, from the ground up.
Groundwork & structure
- Footings
- The concrete base that spreads a building's load into the ground.
- Strip foundation
- A continuous strip of concrete beneath a load-bearing wall.
- Trench fill
- A foundation trench filled almost to the top with concrete, quicker than laying blocks below ground.
- Raft foundation
- A single reinforced concrete slab supporting the whole building, used on weaker ground.
- Hardcore / MOT Type 1
- Crushed stone compacted to form a firm base under slabs and driveways.
- Blinding
- A thin layer of sand or weak concrete over hardcore to give a clean, level surface.
- Damp proof membrane (DPM)
- A plastic sheet laid under a floor slab to stop moisture rising.
- Blockwork
- Walls built from concrete blocks, often the inner leaf of a wall.
- Cavity wall
- A wall built as two leaves with an insulated gap, or cavity, between them.
- Wall ties
- Metal ties that hold the two leaves of a cavity wall together.
- Lintel
- A beam over a door or window opening that carries the load above.
- Padstone
- A strong block that spreads the load where a beam bears onto a wall.
- Wall plate
- A timber along the top of a wall that the roof or joists sit on.
- Acrow prop
- An adjustable steel prop that temporarily supports a structure during works.
Roof & carpentry
- Joists
- The horizontal timbers or steels that carry a floor or ceiling.
- Noggins
- Short timbers fixed between joists or studs to stiffen them.
- Rafters
- The sloping timbers that form a pitched roof.
- Purlin
- A horizontal beam that supports the rafters part-way up their span.
- Roof trusses
- Factory-made triangular frames that form the roof structure.
- Battens
- Thin timber strips fixed across the rafters to carry tiles or slates.
- Ridge
- The horizontal line along the very top of a pitched roof.
- Hip and valley
- A hip is an external roof angle; a valley is the internal gutter where two slopes meet.
- Eaves
- The lowest edge of a roof, where it meets the wall.
- Verge
- The edge of a roof at a gable end.
- Soffit and fascia
- The fascia is the board along the eaves that the gutter fixes to; the soffit is the underside board behind it.
- Flashing
- Metal, usually lead, that weatherproofs the joint where a roof meets a wall or chimney.
- Studwork (stud wall)
- A non-load-bearing internal wall built from a timber frame and plasterboard.
Walls & finishes
- Render
- A cement or lime coat applied to external walls.
- Scratch coat
- The first, keyed coat of render or plaster that the top coat sticks to.
- Dot and dab
- Fixing plasterboard to a wall with dabs of adhesive.
- Skim
- The thin, smooth finishing coat of plaster.
- Self-levelling compound
- A liquid screed that flows out flat to level a floor.
- Beading
- Metal or plastic strips that form neat, straight edges and corners in plaster.
- Chasing out
- Cutting channels into a wall to run cables or pipes.
- Boxing in
- Building a neat casing to hide pipes, wires or beams.
- Making good
- Repairing and finishing the surrounding surfaces after work is done.
- Reveal
- The side face of a window or door opening.
- Cill (sill)
- The bottom ledge of a window opening.
- Architrave
- The moulding around a door or window frame.
- Skirting
- The board along the bottom of a wall where it meets the floor.
People, plant & paperwork
- Site manager (foreman)
- The person running the day-to-day work on site.
- Subcontractor
- A specialist firm brought in for part of the work, such as roofing or electrics.
- Wet and dry trades
- Wet trades use water-based materials (bricklaying, plastering, screeding); dry trades do not (carpentry, dry lining).
- Trade nicknames
- A chippy is a carpenter, a sparky an electrician, a brickie a bricklayer.
- Setting out
- Marking the exact positions of walls and features before building begins.
- Datum
- A fixed reference point that every level on site is measured from.
- Plumb, level and square
- Truly vertical, truly horizontal, and at a true right angle. The basics of good building.
- Muck away
- Removing spoil and waste from site.
- Back-fill
- Replacing soil around new foundations or drainage once the work is done.
- Toolbox talk
- A short on-site safety briefing before work starts.
- RAMS
- Risk Assessment and Method Statement: the health-and-safety paperwork for a task.
- Day works
- Work charged by time and materials rather than at a fixed price.
- Programme
- The project schedule. The critical path is the chain of tasks that sets the finish date.