Building Terms Glossary

Also: JCT HO/O, JCT Building Contract for a Homeowner/Occupier, JCT domestic building contract

A standard building contract published by the Joint Contracts Tribunal, designed specifically for homeowners hiring a builder. It’s plain English, fair to both sides, and far safer than using a builder’s own terms.

Also: jig saw, bayonet saw

A versatile power saw for making curved and intricate cuts in timber, sheet materials, and laminate. Useful for cutting worktop holes for sinks and hobs, and shaping timber where a straight cut won't do.

Also: anti-splinter insert, jigsaw splinter guard, no-splinter insert, jigsaw baseplate insert

A £3–5 plastic baseplate insert that closes the gap around the jigsaw blade, preventing laminate from flexing and chipping. Part of the three-item anti-chip system for worktop cutting (guard + downcut blade + masking tape).

Also: joist hanger brackets

Galvanised steel brackets that support the end of a timber joist where it meets a wall or beam. Available in various sizes to match common joist dimensions. Must be fully nailed with the correct number of fixings as specified by the manufacturer; building control will check this.

Also: impact energy, J rating, joules per blow

The primary specification for comparing breaker power — measures impact energy per blow in joules. Used to match breakers to tasks: 2–5J for tiles/thin screed, 10–20J for brick and lightweight concrete, 30J+ for thick reinforced concrete. A higher J figure means more impact energy per blow. Community research confirms confusion about this metric: spec on paper doesn't always reflect real-world performance between tool quality tiers.