Eighty-three firms — 46 limited companies, weighted toward main-contractor generalists: renovation (24), extensions (22), new builds (22), project management (20). The oldest, C.A. Duquemin, has been building since 1924 and built the Island War Memorial in 1926; 13 firms are GBTEA members. —
Sixty builders — mostly limited companies, weighted toward renovation and extensions; oldest is C.A. Duquemin, trading since 1924.
Ten firms — six in groundworks proper, six in drainage; seven limited companies, the oldest UCF Civil Engineering since 1994.
Eight practices — two RIBA-chartered, two MCIAT-chartered, one RICS surveyor — spanning six parishes, oldest 1996.
Eight firms — most blending masonry with general building, plastering, and extensions; only one (Guernsey Granite) leads with lime work.
Nine of Guernsey's 75 builders take concreting work — split between four structural outfits and five surface-finish trades.
Eight general-builder firms with extensions as primary identity — six also new-build, six renovate, three hold GBTEA membership.
Three diamond-drilling firms — the oldest since 2002, all limited companies cutting concrete, granite, and bunker walls.
One firm per niche, picked for editorial depth.
Carpentry, joinery, painting, decorating, and construction services
Civil engineering and marine construction — geotechnical, piling, utilities.
Architectural design practice — residential, commercial, heritage, leisure
Building & renovation: new builds, damp proofing, basement tanking.
Civil engineering and concrete contracting — formwork, steel fixing, pump hire.
Family building company — new builds, renovations, extensions, carpentry.
Diamond drilling and cutting specialists — concrete, stone, metal, granite.
Limited company providing building services and damp proofing; also trades as TBS
Residential property developer — specialising in commercial-to-residential conversions since 2015.
Tagged in Building & Construction but not in one of the specific niches above.