Two carpenters lifting a roof truss onto a new detached double garage

garage · provisional

Detached garage: how it is priced

A detached garage is a simple building with an honest price: slab, walls, roof, door. The decisions that move it are the door, whether it is insulated and whether there is power.

FICTIONAL WORKED EXAMPLE · 6m × 3.5m (external) · 15.7 m² internal · finish: complete

£44,671.20

inc. VAT at 20% · £37,226.00 before VAT · about £2,377.14/m² · roughly 4 weeks on site

Materials (48 lines, catalogue allowances dated 2026-09-24)£13,079.80Labour (416 person-hours at a blended £30/hr)£12,473.10Provisional allowances (3)£2,005.00Plant£590.00Overheads 10% + contingency 5%£4,222.19Profit (15% markup)£4,855.51

WHERE THE MONEY GOES (AT COST)

External walls£7,877.90Roof£6,274.75Excavation & foundations£2,865.85Windows & external doors£2,430.00Floors£2,032.40Waste removal£1,840.00Drainage£1,130.00Fees & approvals£900.00

Open the full line-by-line example →

Default answers, a blended £30/hr labour rate and dated catalogue allowances. Your job, your rates and your merchant prices will differ — that is the point of the tool. Templates marked provisional are being validated against measured projects; every estimate says so.

What the wizard asks

Attached or detached — Is the garage attached to the house?
Dimensions — Are these internal or external measurements?, Length — length, Width — width (m) — 3–3.5m single, 5.5–6m double, Wall height to eaves
Roof — Roof type, Pitch, Covering, Rooflights
Walls — Wall construction, Outside finish
Ground and foundations — Foundation type, Foundation depth, Ground, Floor construction…
Windows and doors — Openings
Site — Anything to take down first?, Drainage, Access for deliveries and plant
Electrics — Sockets and switches, Light fittings
Inclusions, exclusions and notes — Exclusions, Notes for the estimate

Assumptions this example carries

Garage floor: 150mm concrete slab, power-floated, uninsulated.
Foundations: trench fill 600mm wide × 1.0m deep in GEN1 concrete under all new external walls.
Ground floor: 150mm concrete slab on 150mm compacted hardcore.
External walls: facing brick outer skin, 100mm full-fill insulated cavity, 100mm block inner skin.
Gable roof at 30° on manufacturer-designed trusses, covered in concrete interlocking tile. Truss price is an allowance until the manufacturer quotes.
Rainwater to a new soakaway at least 5m from the building; a percolation test may be required by building control.
The existing consumer unit has spare capacity for the new circuits; if not, a new unit is extra.

Priced work packages

Preliminaries & site setup · Demolition & clearance · Excavation & foundations · Floors · External walls · Roof · Windows & external doors · Drainage · Electrical · Scaffold & access · Plant hire · Waste removal · Deliveries · Testing & certification · Fees & approvals