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Supported projects → Garage with self-contained flat above
A merchant lorry craning a pallet of bricks onto the pavement outside a terraced house
garage · provisional

Garage with self-contained flat above: how it is priced

A flat over a garage is a dwelling, not a garage priced twice: it needs fire separation, its own kitchen and bathroom, separate services and its own building regulations approval.

FICTIONAL WORKED EXAMPLE · 6.5m × 6m (external) · 63.7 m² internal · finish: complete
£149,949.60
inc. VAT at 20% · £124,958.00 before VAT · about £1,961.05/m² · roughly 11 weeks on site
Materials (70 lines, catalogue allowances dated 2026-09-24)£32,432.20Labour (1236 person-hours at a blended £30/hr)£37,083.30Provisional allowances (10)£23,900.00Plant£1,070.00Overheads 10% + contingency 5%£14,172.83Profit (15% markup)£16,298.75
WHERE THE MONEY GOES (AT COST)
External walls£20,313.75Roof£10,430.05Kitchen & bathroom£10,160.00Structural elements£9,361.00Windows & external doors£7,060.00Internal finishes£5,492.40Insulation & internal linings£5,220.25Plumbing & heating£5,045.00

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

  1. Dimensions — Are these internal or external measurements?, Length — length, Width — width, Wall height per storey
  2. Roof — Roof type, Pitch, Covering, Rooflights
  3. Walls — Wall construction, Outside finish
  4. Ground and foundations — Foundation type, Foundation depth, Ground, Floor construction…
  5. Garage windows and doors — Openings
  6. The flat above — Bedrooms, Kitchen, Bathroom, Heating…
  7. Site — Anything to take down first?, Drainage, Access for deliveries and plant
  8. How far do you take it? — Stage of completion, Specification level
  9. Garage electrics — Garage sockets and switches, Garage light fittings
  10. Inside finishes — Plastering, Flooring, Decoration, Internal doors…
  11. Inclusions, exclusions and notes — Exclusions, Notes for the estimate

Assumptions this example carries

  • A separate flat almost always needs planning permission; none is included and the design must show fire separation, sound insulation and its own escape route.
  • 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.
  • Openings over 2.7m wide may need an engineer-specified lintel or steel; a heavy-duty catalogue lintel has been allowed.
  • External walls: facing brick outer skin, 100mm full-fill insulated cavity, 100mm block inner skin.
  • The existing consumer unit has spare capacity for the new circuits; if not, a new unit is extra.
  • External walls: facing brick outer skin, 100mm full-fill insulated cavity, 100mm block inner skin.

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 · Structural elements · Insulation & internal linings · Internal finishes · Plumbing & heating · Kitchen & bathroom

Provisional sums

  • Roof trusses (pitched roofs)
  • Building control fees
  • Ground conditions
  • External staircase
  • First-floor structure design where spans exceed 4.5m
  • Fire separation and protected escape
  • Separate utility connections
  • Kitchen and bathroom supply

Not included

  • Planning application, drawings and party wall matters
  • Furniture, appliances and loose fittings
  • Landscaping and reinstatement beyond the working area
  • Anything found on opening up that could not be seen at survey
  • Driveway, hardstanding and dropped kerb
  • Planning permission for a separate dwelling
  • Council tax and utility account set-up
Related build types
Two carpenters lifting a roof truss onto a new detached double garage

Detached garage

Single or double garage standing on its own.

A bricklayer laying facing bricks on a new cavity wall, string line and spirit level in place

Attached garage

Single or double garage built against the house.

A two-storey side extension under scaffolding, bricklayer on the lift and a labourer loading blocks

Garage with office above

Double garage with a home office or studio on the first floor.

Price your own garage with self-contained flat above

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