A single loft room costs £27,500 to £32,500 as a Velux (rooflight) conversion and £36,500 to £43,000 with a rear dormer at standard spec and West Midlands rates, including VAT, drawings, a structural engineer, Building Regulations and a party wall surveyor. In inner London the same Velux room runs £36,500 to £46,000; in Northern Ireland, £24,500 to £29,500. All figures come from Quoteio’s calculator, and four things decide where your room lands.
- Velux / rooflight: £27,500 to £32,500
- Rear dormer: £36,500 to £43,000
- Hip to gable: £40,000 to £47,000
- Mansard: £45,000 to £52,500
Check your own postcode with the free calculator or browse prices by region.
Why is one loft room so expensive?
Because most of the money goes on making the loft usable at all, not on the room itself. Before you get a single square metre of bedroom, a conversion needs steel beams to carry the new floor, new floor joists, a fixed staircase, fire protection to the escape route, insulation to the roof, scaffold, and electrics and heating run up from the floor below. Quoteio prices lofts as a fixed shell plus a cost per room, because that is how the costs fall on completed jobs.
The result: a second room adds much less than the first. Here is the comparison at standard spec:
| Loft type | One room | Two rooms | Second room adds about |
|---|---|---|---|
| Velux / rooflight | £27,500 to £32,500 | £34,500 to £40,500 | £7,600 |
| Rear dormer | £36,500 to £43,000 | £47,000 to £55,000 | £11,200 |
Standard spec, West Midlands rates, VAT and fees included. “Second room adds” is the difference between the two calculated totals.
If your loft has the floor area for two rooms, or a room plus an en-suite, it is worth pricing both before deciding. Our full loft conversion cost guide covers larger conversions.
What are the 4 things that push up the price?
1. The type of conversion
This is the biggest lever. A Velux conversion works inside the existing roof shape and adds rooflights, so there is no new roof structure. A dormer builds a box out from the back slope, which buys headroom and floor space but needs its own roof, walls and cladding. A hip to gable rebuilds a sloping end of the roof as a vertical wall. A mansard rebuilds the whole rear slope almost vertically and is the most structural of the four.
| One loft room, standard spec | Typical price inc VAT |
|---|---|
| Velux / rooflight Works within the existing roof | £27,500 to £32,500 |
| Rear dormer Adds headroom and floor space | £36,500 to £43,000 |
| Hip to gable Rebuilds a hipped end as a gable | £40,000 to £47,000 |
| Mansard Rebuilds the rear slope | £45,000 to £52,500 |
Your roof often makes the choice for you. If there isn’t enough headroom under the ridge, a Velux room may not be possible, and a detached or end-of-terrace house with a hipped roof may need a hip to gable to fit a staircase.
2. The finish level
Moving from standard to high spec lifts a one room Velux conversion from £27,500 to £32,500 to £35,500 to £41,500, with mid-range sitting at £30,500 to £36,000. For a dormer the high spec figure is £46,500 to £54,500. Better spec means things like more rooflights, oak or bespoke staircases, built-in storage in the eaves and more detailed drawings.
3. Adding an en-suite
Putting a shower room in the loft adds sanitaryware, tiling and a waste connection. At standard spec it takes a one room Velux conversion to £29,000 to £34,000 and a one room dormer to £38,000 to £44,500. The hidden cost is often the waste run: if the soil stack is on the other side of the house, a builder may need a longer drain route or a pumped system, which they will price after a survey.
4. Where you live
The same room costs noticeably more in London and the South East than in the North East, Wales or Northern Ireland, because labour, scaffold access and party wall work all vary. Here are one room conversions in every UK region:
| Region | One room, Velux | One room, dormer |
|---|---|---|
| Inner London | £36,500 to £46,000 | £48,000 to £61,000 |
| Outer London | £32,500 to £41,500 | £43,500 to £55,000 |
| South East | £30,500 to £37,500 | £40,500 to £49,500 |
| East of England | £29,000 to £35,500 | £38,500 to £47,000 |
| South West | £28,500 to £34,500 | £37,500 to £46,000 |
| East Midlands | £27,000 to £32,500 | £35,500 to £43,000 |
| West Midlands | £27,500 to £32,500 | £36,500 to £43,000 |
| North West | £27,000 to £32,500 | £35,500 to £43,000 |
| Yorkshire and the Humber | £26,000 to £31,500 | £34,500 to £42,000 |
| North East | £25,500 to £31,000 | £33,500 to £41,000 |
| Wales | £26,000 to £31,500 | £34,500 to £42,000 |
| Scotland | £27,000 to £33,000 | £35,500 to £43,500 |
| Northern Ireland | £24,500 to £29,500 | £32,000 to £39,000 |
Open a regional page for more detail, for example London, Yorkshire and the Humber or Scotland, or put your postcode into the calculator. Our methodology page explains how each region is priced.
What else can catch you out?
These don’t show up until a builder has been in the loft, so they are not in a calculator estimate. Ask about each one when you get quotes:
- Head height. If the space under the ridge is tight, the options (a dormer, or lowering the ceilings below) add real cost.
- Where the stairs land. The new staircase has to come down somewhere, often over the existing stairs. Losing part of a bedroom or a box room to it is common.
- Steels and party walls. In a semi or terrace, new steels usually sit in the party wall, which means serving notice on your neighbours.
- Water tanks and the boiler. Tanks in the loft need moving or removing, and an older boiler may not have the capacity for extra radiators.
- Roof condition. Old or damaged tiles are often best replaced while the scaffold is up.
Do I need planning permission or Building Regulations?
Many loft conversions in England can go ahead under permitted development, especially Velux and rear dormer conversions that stay within the volume and height limits and don’t face the road. Mansards, front dormers, flats and homes in conservation areas usually need full planning. Rules differ in Wales, Scotland and Northern Ireland, so check with your council. Quoteio includes the fee for a lawful development certificate, which confirms the work is permitted.
Building Regulations approval is needed in almost every case where the loft becomes a habitable room. Building Control will usually check the structure, fire escape, staircase, insulation and ventilation.
Is one loft room the right move?
A single loft room is often the cheapest way to add a bedroom without losing garden, but the gap between one room and two is small enough that it is worth pricing both. If you are weighing the loft against selling up, our loft conversion vs moving guide sets the two side by side. If you have an integral garage, compare a garage conversion too. Then get three written quotes and use Quoteio to sense-check them for your postcode.
Common questions
Is it worth converting a loft for just one room?
It can be, but compare it with two. Most of the cost of a loft is the shell: steels, the new floor, the staircase and the dormer if you have one. On Quoteio a one room Velux conversion costs £27,500 to £32,500 at West Midlands rates and a two room one costs £34,500 to £40,500, so the second room adds far less than the first. If your loft has the space, pricing both is worthwhile.
Does a loft room need planning permission?
Many loft conversions are permitted development in England, particularly Velux and rear dormer conversions that stay within volume and height limits and do not face the road. Mansards, front dormers, flats, listed buildings and conservation areas usually need full planning. Quoteio includes the fee for a lawful development certificate, which confirms the work is permitted. Always check with your council before work starts.
How much head height do I need for a loft room?
A common rule of thumb is about 2.2m from the top of the ceiling joists to the underside of the ridge, because the new floor and insulation take some of that height. If you have less, a dormer can add headroom, while lowering the ceilings below is possible but expensive. A builder or surveyor should measure before you commit.
Does a loft room count as a bedroom?
To be described as a bedroom it should have Building Regulations sign-off, which covers fire safety (a protected escape route and suitable windows), a fixed staircase, insulation and structure. A loft room without sign-off is usually marketed as a hobby room or storage, which can affect what it adds to the value of your home.