Building Terms Glossary

Also: first fix nailer, second fix nailer, framing nailer, brad nailer, finish nailer, coil nailer, pneumatic nailer, gas nailer

A pneumatic or gas-powered tool for driving nails rapidly. First fix nail guns fire larger nails for framing and structural work. Second fix nail guns fire smaller brad nails for trim, skirting, and architrave. Saves enormous time compared to hand nailing.

Also: nail set, pin punch

Small steel punch for driving nail heads below the surface of timber

Also: corroded tile nails, ferrous nail corrosion, tile nail corrosion

Also: gas fuel cell, Paslode fuel cell, nail gun gas cartridge, cordless nailer gas cell

The key consumable for gas-powered cordless nail guns (Paslode IM350+, IM65A). A proprietary pressurised gas canister that powers the combustion cycle — not a battery. Each cell provides approximately 1,000–1,100 shots at ~£20–21/cell (2026). Fuel cells are a recurring operational cost. Must be manufacturer-approved — third-party cells cause misfires and void warranty. Must be kept warm in cold weather to maintain consistent gas pressure.

Also: round wire nails, ring shank nails, clout nails, galvanised nails, framing nails, brad nails, strip nails

Steel wire nails in various types: round wire (general purpose), ring shank (superior holding power for sheet materials), clout (large flat head for felt and membrane), and galvanised (external use). Sold in boxes by weight. Ring shank nails are preferred for structural sheet material fixing.

Also: National Association of Professional Inspectors and Testers

The National Association of Professional Inspectors and Testers. A UK certification body for electricians, plumbers, and heating engineers. NAPIT-registered electricians can self-certify electrical work under the competent person scheme.

Also: TG20:21, TG20, NASC TG20:21 Scaffolding Guidance

The industry standard configuration guidance for tube and fitting scaffolding in the UK, published by the National Access and Scaffolding Confederation. A scaffold assembled to TG20 does not require bespoke structural calculations. Referenced by HSE as the definitive reference for residential scaffolding.

Also: Wickes, B&Q

High-street and retail park stores selling building materials, kitchens, bathrooms, and tools to both trade and DIY customers

A statutory designation where permitted development rights are restricted. The National Park Authority acts as the local planning authority and applies tighter planning controls than standard councils.

Also: NPPF, NPPF 2024

The government's national planning policy document that planning decisions and appeals must be consistent with.

Also: neighbour notification

The council's process of notifying and consulting neighbours as part of a planning application. Neighbours can object, and the planning officer must address those objections in the decision report. Objections do not automatically mean refusal.

Also: National House Building Council, nhbc.co.uk, NHBC register, NHBC Standards

National warranty and insurance provider operating a register of builders who have demonstrated financial security and technical competence through commercial and technical assessment.

Also: Buildmark, NHBC warranty, NHBC 10-year warranty, new build warranty

NHBC's structural warranty for new-build homes providing 10-year cover against major structural defects. Frequently confused by homeowners as a substitute for a local authority completion certificate — solicitors and mortgage lenders require both.

Also: NHBC Standards 2025, NHBC technical standards

Technical standards published by the National House Building Council, applied to homes covered by an NHBC warranty. Updated annually. Acts as the de facto baseline for new-build construction quality in the UK and is widely referenced by LABC and Approved Documents. Chapter 6.1 covers external masonry walls, Chapter 6.2 covers timber-framed walls, Chapter 7 covers roofs.

Also: NHBC 6.2.12, NHBC vapour control layer requirement

NHBC standard requiring vapour control layers on the warm side of insulation in externally framed walls. Specifies three compliant options: minimum 125 micron polythene (500 gauge), vapour control plasterboard with metallised film, or proprietary membrane with UKAS third-party certification.

Also: NHBC 3.2.5, NHBC cold weather masonry, NHBC masonry frost protection

Sets the authoritative cold-weather thresholds for masonry: do not lay when temperature is below 3°C and falling; may resume when 1°C and rising if expected to exceed 3°C. Frost-damaged walling must be demolished and rebuilt.

Also: NHBC 4.2, NHBC building near trees

Provides authoritative minimum foundation depth tables based on tree species, soil plasticity index, and distance from building. Applied by structural engineers and building control inspectors.

Also: NHBC 4.3, NHBC strip and trench fill foundations

Governs the design of strip and trench fill foundations on level sites, the two most common foundation types for domestic extensions.

Also: NHBC 5.1, NHBC substructure and ground-bearing floors

Substructure and ground-bearing floors. Governs minimum slab thickness (100mm), fill compaction layer limits (225mm per layer), fill depth limit before suspended floor is required (600mm), DPM lapping requirements (300mm), and sand blinding requirement over sharp hardcore. Building control inspectors reference this at oversite inspection.

Also: NHBC 5.3, NHBC drainage below ground

Drainage below ground. Governs minimum pipe gradients (1:40 for <1 L/sec flows, 1:80 for higher flows), granular surround requirements (100mm below pipe, to 150mm above crown), backfill layer limits (300mm), and mechanical compaction threshold (>450mm above pipe crown). Building control inspectors reference this at drainage inspection.

Also: NHBC 5.4, NHBC damp-proofing standard, NHBC chapter 5.4

NHBC specification for DPC height, continuity, cavity tray requirements, and workmanship standards. NHBC-registered builders must comply with it alongside Approved Document C.

Also: NHBC 6.1.17, NHBC DPCs and cavity trays

Governs DPCs and cavity trays in external masonry walls. Updated January 2024 to require preformed cavity trays at pitched roof abutments, T-junctions, door thresholds, and penetrations. Also specifies weephole positioning.

Also: NHBC 6.1.20, NHBC external masonry cold weather, NHBC masonry weather protection

Specifies that newly laid masonry and cavity insulation must be covered with two layers when work stops: a hessian thermal layer and a waterproof plastic sheet. The companion chapter to 3.2.5 for physical protection of work in progress.

Also: NHBC 6.5, NHBC steelwork standard

The authoritative industry standard for domestic steelwork installation: 100mm minimum bearing onto padstone, 200mm padstone for in-line steels, minimum 10N/mm² padstone compressive strength, padstone depth matching masonry coursing.

Also: NHBC 7-2-19, NHBC chapter 7.2.19, NHBC fixing tiles and slates standard

Also: NHBC 7.2.15, NHBC ventilation vapour control and insulation, NHBC Chapter 7.2.15

Also: NHBC 7.2.17, NHBC battens standard, NHBC Chapter 7.2.17

Also: NHBC 7.2.20, NHBC weathering details, NHBC Chapter 7.2.20

Also: NHBC 7.2.8, NHBC pitched roof restraint

Governs lateral restraint of pitched roofs. Specifies holding-down straps as 30x5mm galvanised steel, minimum 1m long, at maximum 2m centres, with minimum three fixings into blockwork.

Also: NHBC 9.1, NHBC A Consistent Approach to Finishes, NHBC Chapter 9.1

The NHBC standard 'A Consistent Approach to Finishes' that defines acceptable tolerance ranges for residential construction finishes. Key tolerances: walls max 8mm out of plumb in 3m, wall flatness ±3mm in 2m, floor level 3mm per metre, floor flatness ±5mm in 2m, door gaps max 4mm, tiling ±5mm in 250mm.

Also: NHBC 9.1.8, NHBC fitted furniture

NHBC standard specifying fitted furniture must be installed after plastering and decoration is substantially complete.

NHBC technical standard covering internal wall finishes and plastering requirements for new builds and extensions

Also: NHBC 9.3.4, NHBC screed over UFH

NHBC Standards governing screeds over underfloor heating: minimum 25mm pipe cover, bay subdivision (max 40m² / 8m length), expansion joints at doorways, pressure testing before and after screed pour, and as-built pipe drawings on site.

Also: NHBC 9.4.3, NHBC cupboards and fitments

Primary NHBC standard governing kitchen unit installation: circulation space, fixing requirements, worktop sealing, and shelf support standards.

Also: NHBC 9.5, NHBC Painting and Decorating

NHBC chapter governing painting and decorating in new builds and extensions. Sets the 2m natural daylight defect assessment method, minimum two-coat requirement, sealing coat requirement for new plaster and dry lining, and prohibits painting in damp, frost, or sub-2°C conditions.

Also: National Inspection Council for Electrical Installation Contracting

The National Inspection Council for Electrical Installation Contracting. A leading UK certification body for electricians. NICEIC-registered electricians can self-certify electrical work under the competent person scheme, avoiding a separate building control application for Part P compliance.

Also: deemed refusal appeal, failure to determine

A distinct appeal route available when the council fails to decide an application within the statutory determination period.

Also: notch trowel, tile adhesive trowel, square-notch trowel, V-notch trowel, 3x3mm notched trowel, 10mm notched trowel, 12mm notched trowel

Primary tool for spreading tile adhesive to the correct bed thickness. Notch size determines adhesive coverage: 3×3mm for decoupling membrane, 10–12mm square-notch for large-format floor tiles per BS 5385-1:2018.

Also: Part P notifiable work, notifiable work under Part P, Part P registration

Electrical work in dwellings that must either be carried out by a registered competent person scheme electrician or notified to building control before starting. Includes all new circuit installation.