Key Takeaway
A garage conversion is one of the quickest ways to add a bedroom, home office or living room to your home — but the timeline from first conversation to usable room involves more stages than most homeowners expect. Here's the complete picture.
The Realistic Garage Conversion Timeline
Homeowners frequently underestimate how long a garage conversion takes from first enquiry to move-in day. The construction phase — typically 4 to 8 weeks — is just one part of a process that starts several months earlier. Understanding the full timeline helps you plan properly, line up the right contractor, and avoid the frustration of unexpected delays.
Here's the complete timeline for a straightforward attached or integral garage conversion in Hampshire in 2026.
Stage 1: Complimentary Consultation and Feasibility (Week 1–2)
The process starts with a conversation about what you want to achieve. We assess the feasibility of your garage conversion — the floor level relative to the house, drainage options, structural implications of removing the garage door, insulation strategy, and whether planning permission is required.
For most integral and attached garages, planning permission is not needed. The change of use to habitable space typically falls within Permitted Development rights, with a few exceptions (conservation areas, Article 4 Direction areas, some new-build estates where a planning condition requires the garage to remain as parking). We confirm your position at this stage.
Stage 2: Design and Drawing Preparation (Weeks 2–5)
Once you instruct us (with a £250+VAT deposit), we visit the property to take accurate measurements. For a garage conversion, the drawing package typically includes:
- Existing and proposed floor plans showing the garage layout, new internal arrangement, window and door positions
- Elevations showing the new front elevation with the garage door replaced by a window and new facing materials
- Construction cross-sections through the walls, floor and ceiling showing the full thermal envelope — wall insulation build-up, floor construction (usually a new insulated concrete slab or insulated overlay), roof or ceiling insulation
- Structural details for the new lintel or opening into the house if the internal door is being widened
- Block plan for the Building Notice submission
This package is typically completed within 3 weeks of the site visit.
Stage 3: Building Regulations Submission (Weeks 5–7)
The Building Notice is submitted to your local council's Building Control team. For a Building Notice (the simpler route), there is no formal wait for approval — the notice takes effect immediately and an inspector visits during construction. You can start on site as soon as the notice is submitted, provided all the technical design work is done.
If you opt for a Full Plans Application, allow 5 weeks for the council to check and approve the drawings before work begins. This route is worth considering if your conversion involves complex structural work or drainage connections to a public sewer.
Stage 4: Finding a Contractor (Weeks 4–8, in parallel)
While drawings are being prepared, you should be getting quotes from contractors. A garage conversion is smaller than a full extension but still requires a builder with experience in conversion work — particularly insulation installation and damp-proofing, which are areas where cutting corners leads to problems. Our Premium Package includes contractor tender management, sending your drawings to vetted firms and producing a comparison report.
Expect to allow 2–4 weeks to receive and compare quotes, make a decision, and agree a start date with your chosen contractor.
Stage 5: Construction (Weeks 8–14)
A straightforward attached garage conversion typically takes 4 to 6 weeks on site. The main phases are:
- Week 1: Strip out — remove garage door, existing finishes, any storage
- Week 1–2: Structural work — new lintel over the former garage door opening, new window frame fitted
- Weeks 2–3: Floor — new insulated concrete slab or raised timber floor with insulation
- Weeks 2–4: Walls and ceiling — internal wall insulation, plasterboard and skim
- Week 4–5: First fix — electrics, any plumbing if a bathroom is being included
- Week 5–6: Second fix and finishes — skirting, doors, decoration
Building control will make 2–3 site visits during construction to inspect foundations, structure, insulation and electrical work.
Stage 6: Completion and Building Control Sign-Off (Week 14–16)
Once construction is complete, the building control inspector makes a final visit and issues a Completion Certificate. This document is proof that the works comply with Building Regulations — your solicitor will ask for it when you come to sell. Keep it safe.
Total Timeline: 3 to 5 Months
From first consultation to usable room, most garage conversions in Hampshire take between 3 and 5 months. The design and planning stages are often the longest part — once drawings are done and a contractor is booked, the build itself moves quickly.
Hampshire Build typically delivers garage conversion drawing packages within 3 weeks of the site visit. Book a complimentary consultation to discuss your project and get a fixed fee for the design work.
