Garage Conversion Cost Guide for Brighton & Hove Homes

Realistic budgets, hidden extras and money-saving tips for coastal properties.

Why Garage Conversion Costs Vary So Widely

Brighton & Hove garages range from 1930s brick boxes to Victorian coach houses made of bungaroosh. Key drivers that push budgets up or down include:

  • Structural upgrades – steel goal-posts, underpinning shallow footings, hot-lime pinning for bungaroosh

  • Services – plumbing for en-suites, new consumer unit, data cabling, MVHR ventilation

  • Finishes – engineered oak and bespoke joinery versus sheet vinyl and off-the-shelf cabinets

  • Compliance fees – Building Control, structural engineer, SAP assessor, air-pressure test

  • Planning – full application and heritage reports if the façade faces a conservation street

Typical Spend Bands (Spring 2025)

Lean home office spec

  • Basic single garage, no bathroom, entry-level electrics

  • Expect £28 000 – £34 000 plus VAT

Mid-spec guest room with WC

  • New soil pipe or macerator, better insulation, two rooflights

  • Budget £38 000 – £45 000 plus VAT

High-spec annexe or gym

  • Double garage, en-suite shower, UFH, bespoke storage, acoustic floor

  • Range £55 000 – £70 000 plus VAT

Prices assume standard brick construction; bungaroosh remediation adds roughly 10–15 percent.

Cost Breakdown – Where the Money Goes

Design and approvals

  • Measured survey and concept drawings

  • Planning or lawful-development fee

  • Structural calculations

Structural and shell

  • Garage-door removal and goal-post frame

  • New cavity-wall infill or glazed screen

  • Floor slab insulation and screed

Envelope upgrades

  • Wall insulation, battening and lime or gypsum plaster

  • Roof insulation under deck or rafters

  • External lime render or brick-slip cladding (if required)

First-fix services

  • New ring main on RCBOs

  • Plumbing runs for radiators or UFH manifold

  • MVHR or humidity-sensing extract ducting

Second-fix and finishes

  • Flooring, skirting, architraves

  • Socket plates, switchgear, light fittings

  • Decoration and snagging

Professional and statutory

  • Building Control plan check and inspections

  • SAP calc and U-value report

  • Air-pressure test (optional but future-proofs EPC)

Hidden Extras Brighton Homeowners Encounter

  • Replacing corroded steel lintels in sea-air zones

  • Upgrading fuse board if spare capacity is lacking

  • Lime-render patches where bungaroosh walls crumble under old cement

  • Cycle storage or transport statements requested by planners

  • Unforeseen drainage reroutes when sewers run beneath the slab

Keep a 10–15 percent contingency for surprises—especially on period property conversions.

Value Boost and Payback

  • A heated, fully insulated office or bedroom in Brighton can add £40 000–£60 000 to market value, often covering the build cost.

  • EPC uplift by one band reduces energy bills, improving lender and buyer appeal.

  • Self-contained annexes generate £70 – £120 per night on Airbnb once council licensing is in place.

Financing Options

  • Further-advance mortgage at 4–5 percent APR over the existing term

  • Home-improvement loan from local credit union (typical 6.9 percent APR)

  • Green-energy grants where external-wall insulation is included

  • 0 percent VAT on certain energy-saving measures until 2027

Cost-Saving Tips That Don’t Compromise Quality

  • Retain part of the original slab if depth and damp levels allow—saves screed pour.

  • Choose factory-finished roof lights; onsite frame painting adds labour.

  • Run heating off existing boiler circuit instead of installing a standalone electric system.

  • Opt for mineral-wool insulation in timber studs: cheaper than PIR and breathable for bungaroosh.

  • Stage the project: shell out and first fix in phase one, finishes later when budget allows.

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