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.
Eight practices — two RIBA-chartered, two MCIAT-chartered, one RICS surveyor — spanning six parishes, oldest 1996.
Nine of Guernsey's 75 builders take concreting work — split between four structural outfits and five surface-finish trades.
Ten firms — six in groundworks proper, six in drainage; seven limited companies, the oldest UCF Civil Engineering since 1994.
Eight firms — most blending masonry with general building, plastering, and extensions; only one (Guernsey Granite) leads with lime work.
Eight general-builder firms with extensions as primary identity — six also new-build, six renovate, three hold GBTEA membership.
Four demolition firms, four parishes — one Channel Islands-licensed asbestos specialist, one diamond driller, two general contractors.
Three firms on the island — one pure specialist, one broader builder with cavity-membrane accreditation, one limited company trading as TBS.
Three limited companies — Island Electrics (1985), NE Electrics (2012), Bright Electrical (2020); two NICEIC-registered.
Three project-management practices — PlanB (2005) leading with a Chartered Institute Fellow, Concept 360 (2017), and GY Developments.
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
Architectural design practice — residential, commercial, heritage, leisure
Civil engineering and concrete contracting — formwork, steel fixing, pump hire.
Civil engineering and marine construction — geotechnical, piling, utilities.
Building & renovation: new builds, damp proofing, basement tanking.
Family building company — new builds, renovations, extensions, carpentry.
ACAD Certificate of Excellence holder & ISO 9001/14001 accredited; asbestos surveys & removal
Damp proofing & waterproofing; condensation, mould, rising & penetrating damp
Electrical contractor — installations, EICR, solar, fire, EV charging
Construction company with over 45 staff; building, renovation, landscaping
Diamond drilling and cutting specialists — concrete, stone, metal, granite.
Tagged in Building & Construction but not in one of the specific niches above.