The short answer
A straightforward single garage conversion typically takes around 2–6 weeks on site, with simpler dry rooms at the shorter end and conversions involving plumbing, structural changes or a difficult floor taking longer. On top of the build, allow time beforehand for design, building control and any drying-out of plaster. The exact timescale depends on the garage, the room and the contractor’s schedule, so treat these as typical illustrations rather than a promise.
Most homeowners want a realistic idea of how long the disruption will last. A garage conversion is one of the quicker ways to add a room because the shell already exists, but the timescale varies with the scope. This guide sets out typical durations and what pushes them up or down. These are general pointers, not a programme for your specific job. For what the work covers, see what is involved in a garage conversion; for cost, see the main cost guide.
Timescales at a glance
- Typical build ~2–6 weeks on site
- Simple dry room Shorter end
- Kitchen or bathroom Longer
- Before site Design & building control
- Adds time Plumbing, structural work
- Also allow Plaster drying, finishing
Typical timescales
For a single attached garage being turned into a dry room such as a bedroom, office or living room, the on-site work is commonly in the region of 2–6 weeks. A simple conversion with minimal services sits at the lower end; one that needs plumbing, significant structural change or extensive floor work sits higher. Before the build begins, allow time for design and arranging building control, and after the main work, plaster needs to dry before final decoration. These are typical illustrations — your contractor will give a programme for your job.
What affects the timescale
Several things move the timescale. Adding plumbing for a kitchen or bathroom takes longer than a dry room. A garage floor that needs raising and damp-proofing, or walls that need structural attention, adds days. The condition of the existing garage, the room you want, the weather, material lead times and the contractor’s availability all play a part. A clear, agreed scope at the outset is the best way to keep the job on schedule.
| Type of conversion | Typical on-site time |
|---|---|
| Simple dry room (office, bedroom) | Around 2–3 weeks |
| Living room with some services | Around 3–4 weeks |
| Kitchen, utility or bathroom | Around 4–6 weeks or more |
| Plus structural or floor work | Adds time |
Planning your timeline
To plan realistically, add the lead time for design and building control before the on-site weeks, and a short period afterwards for plaster to dry and final finishing. Most conversions do not need planning permission, which keeps the timeline shorter than an extension; check the planning permission guide to be sure. This is general information; your timescale depends on the garage, the room and the contractor, so seek a programme from a garage conversion specialist who handles building control.
Compare garage conversion quotes
A good contractor gives you a price and a realistic timeline. Compare itemised quotes from FMB-registered or building-control-approved specialists in your area.
Frequently asked questions
How long does a garage conversion take?
For a single garage, the on-site work is commonly around 2–6 weeks — simpler dry rooms at the shorter end, and conversions with plumbing, structural work or a difficult floor taking longer. Allow extra time for design, building control and plaster drying.
What makes a conversion take longer?
Adding plumbing for a kitchen or bathroom, raising and damp-proofing the floor, structural changes, awkward access, poor weather and material lead times all add time. A clear, agreed scope and an experienced contractor help keep the job to schedule.
Do I need to allow time before the build starts?
Yes. Allow time to design the room and arrange building control before work begins, and a short period afterwards for plaster to dry and final decoration. Most conversions avoid planning permission, which keeps the overall timeline shorter than an extension.
Sources & further reading
- Federation of Master Builders (FMB) — garage conversion timescales and registered builders
- Planning Portal — permitted development for garage conversions
- GOV.UK / Building Regulations Approved Documents — standards for habitable rooms
- Local authority Building Control — inspections during the work
This is general information, not a programme or advice for your specific job. Timescales depend on your garage, the room and the contractor, so seek a programme from your specialist. The work should be carried out by an FMB-registered or building-control-approved garage conversion specialist. We are an independent information and introduction service, not a builder.