House extensions,
built to outlast the mortgage.

Extensions across Greater Manchester

An extension is the biggest single improvement most homeowners will ever make — and the one where builder quality matters most. Structural steels, foundations, damp-proofing and the junction between old and new all get buried behind plasterboard. If they’re wrong, you find out years later.

The Cahill Construction Group has been building extensions across Manchester for over 25 years. We handle the full scope: excavation and foundations, structural openings and steelwork, roofing, glazing, first and second fix, plastering and decoration — with building control inspections passed at every stage.

What we build

• Single storey rear extensions — the classic open-plan kitchen-diner, with roof lanterns, bi-folds or oversized sliders onto the garden.
• Double storey extensions — extra bedroom and bathroom above, living space below. The best cost-per-square-metre of any extension type.
• Side-return and wraparound extensions — reclaiming dead space on period semis and terraces to transform the whole ground floor.
• Garden rooms and garage conversions — habitable, insulated, fully certified spaces, not glorified sheds.

The details that separate our extensions

Matched brickwork sourced properly, not “close enough.” Insulation done to spec so the new room isn’t the cold one. Level thresholds between old and new floors. Rainwater goods and rooflines that look like they were always there. These aren’t extras — they’re the job.

See a recent example: our single storey rear extension in Northwich, documented from foundation to finished patio.

Read our guide on what an extension costs in Manchester before you start collecting quotes.