01 / 07 Loft conversion types
Velux Loft Conversions
A Velux loft conversion, also called a rooflight or roof window loft conversion, turns your loft into a usable room without changing the shape of your roof. Roof windows are fitted into the existing roof slope, the floor is strengthened, a staircase is added, and the space is insulated and finished as a bedroom, office or playroom.
Because the roof structure stays largely as it is, a Velux conversion is usually the simplest, quickest and lowest-cost type of loft conversion. It works best in lofts that already have good head height. We survey your loft first and tell you honestly whether a Velux conversion will give you the room you want, or whether another type would suit your house better.
- Part ofLoft Conversions
- Our process7 clear steps
- Answered here6 common questions
- FreeSurvey & itemised quote
01Suitability
Is Your Loft Suitable for a Velux Conversion?
Because the roof shape does not change, the space you get is the space you already have. At the survey we check:
- Head height: The height from the top of the ceiling joists to the underside of the ridge. The new floor, insulation and ceiling all take up some of that height, so as a rule of thumb, around 2.2 metres or more is needed before work starts.
- Roof pitch: A steeper roof gives more usable floor area with full standing height. A shallow roof leaves more of the room under the slope.
- Roof structure: Older cut roofs with rafters and purlins are usually straightforward. Modern trussed roofs need a structural redesign first; see our trussed roof loft conversion page.
- Room for the stairs: The new staircase needs enough headroom where it arrives in the loft, which is easier where the ridge is high.
- Obstacles: Water tanks, chimney breasts and flues that may need moving.
If your head height is too low, a dormer loft conversion adds full-height space by extending the roof. Lowering the ceiling of the room below is another option.
02Benefits and limits
Advantages and Limitations
| Advantages | Limitations |
|---|---|
| Usually the lowest-cost loft conversion | Adds no extra head height |
| Roof shape stays the same | Less full-height floor area than a dormer |
| Often no planning application needed | Needs good existing head height |
| Plenty of natural light from above | En-suite options depend on where the height is |
| Less disruption, with most work done from inside | Sloping ceilings limit furniture placement |
03Velux vs dormer
Is a Velux Loft Conversion Cheaper Than a Dormer?
Usually, yes. A Velux conversion keeps the existing roof, so there is less structural work, less scaffolding time and less new roof to build. A dormer extends the roof outwards to create full-height walls and more usable floor space, which costs more but gives more room.
| Velux conversion | Dormer conversion | |
|---|---|---|
| Relative cost | Lower | Higher |
| Relative build time | Shorter | Longer |
| Usable space | The space within the existing roof | More full-height space |
| Planning | Often permitted development | Often permitted development (rear dormers), within limits |
| Best for | Lofts with good head height | Lofts that need more height or floor area |
04Windows
Choosing Your Roof Windows
- Centre-pivot windows: The most common type. They rotate in the middle, so they are easy to clean from inside.
- Top-hung windows: Open outwards from the top, giving a clear opening and a better view out. They can form part of the escape plan where the regulations allow.
- Balcony-style roof windows: Open out to create a small standing area at the window. The planning position needs checking, because balconies are not permitted development.
- Conservation rooflights: Slim, low-profile frames designed for period homes and conservation areas.
- Blinds and controls: Blackout blinds are useful in bedrooms, and electric or solar-powered windows help where they are out of reach. We can also fit blinds through our blind fitting service.
The number, size and position of the windows are planned around the room layout, the light you want and the rafters, which are trimmed with new timbers wherever they are cut.
05Planning
Do You Need Planning Permission for a Velux Loft Conversion?
Often not. Adding roof windows to a house in England is usually permitted development if:
- Projection: The windows do not project more than 150 millimetres beyond the existing roof slope.
- Height: No part is higher than the highest part of the roof.
- Side windows: Side-facing windows are obscure-glazed and non-opening below 1.7 metres above the floor.
Planning permission may be needed for flats and maisonettes, for listed buildings (which need listed building consent), in some conservation areas (especially for windows on the front roof slope), and where an Article 4 direction applies. We check your property at the survey and can apply for a Lawful Development Certificate for written confirmation.
06Building regulations
Building Regulations for Velux Loft Conversions
Although the roof shape does not change, turning a loft into a habitable room still needs building regulations approval. The main areas are:
- Floor structure: New floor joists strong enough for a room, and trimmers around each roof window opening.
- Fire safety: A protected escape route down the stairs, fire-resisting doors onto the stairway, and mains-powered, interlinked smoke alarms.
- Stairs: A permanent staircase with enough headroom.
- Insulation and ventilation: Insulation to the roof slopes, walls and floor, and background ventilation.
We arrange the building control inspections and hand you the completion certificate at the end.
07Cost
What Affects the Cost of a Velux Loft Conversion?
Every loft is priced after a free survey, and you receive a written, itemised quote. The main factors are:
Every factor is priced line by line after your free survey — no guesswork, staged payments.
Book a free loft survey- 01
Size of the loft and the amount of floor to be strengthened.
- 02
Number and type of roof windows.
- 03
Staircase
A straight flight costs less than a winding or bespoke stair.
- 04
Moving tanks, flues or chimney breasts.
- 05
En-suite
Plumbing, and a Saniflo installation where the waste cannot run by gravity.
- 06
Finish
Electrics, heating, storage in the eaves, flooring and decoration.
- 07
Fees
Building control, structural calculations and any party wall costs.
Timescale · 08
How Long Does a Velux Loft Conversion Take?
It is usually the quickest type of loft conversion, because the roof is not rebuilt. Most of the work is done inside the loft. The main disruption comes when the new staircase is connected to the floor below. The size of the loft, the number of windows and whether you add an en-suite all affect the programme, which is set out in your quote.
One team · 09
Finished by One Team
We carry out every trade the conversion needs: new circuits, lighting and smoke alarms through our domestic electrical installation service, heating through our radiator installation service, and plastering and painting, so the room is ready to use on handover.
If you want to finish the room yourself, we can carry out the structure, windows and floor only as a shell loft conversion.
10Process
Our Velux Loft Conversion Process
Planned before we start, managed by one project manager, signed off at the end.
- 01
Free loft survey
Head height, roof structure, stair position and window positions.
- 02
Design and quote
Drawings, structural calculations and an itemised quote with a programme.
- 03
Approvals
Building regulations approval, a planning check or Lawful Development Certificate, and party wall notices if needed.
- 04
Floor and windows
New joists, window openings trimmed and roof windows fitted, keeping the house weathertight.
- 05
Insulation and first fix
Wiring, heating pipework, insulation and plasterboard.
- 06
Staircase and finishing
The staircase goes in, then plastering, second fix and decorating.
- 07
Sign-off and handover
Building control completion, certificates and a final walk-round.
11Areas
Velux Loft Conversions Across London
We carry out Velux loft conversions across London, with a focus on east and south-east London. Find out more on our pages for Velux loft conversion in London, Velux loft conversion in Ilford, Velux loft conversion in Barking, Velux loft conversion in Dagenham, Velux loft conversion in East Ham and Velux loft conversion in Orpington.
12FAQs
Velux Loft Conversion FAQs
How much does a Velux loft conversion cost?
It depends mainly on the size of the loft, the number of roof windows, the staircase and whether you add an en-suite. It is usually the lowest-cost type of loft conversion because the roof shape does not change. We give you a fixed, itemised quote after a free survey.
Do you need planning permission for a Velux loft conversion?
Often not. Roof windows are usually permitted development on houses if they do not project more than 150 millimetres from the roof slope and side windows are obscure-glazed. Flats, listed buildings, some conservation areas and Article 4 areas need permission.
Is a Velux loft conversion cheaper than a dormer?
Usually, yes. It keeps the existing roof, so there is less structural work and less new roof to build. A dormer costs more but adds more full-height space.
How long does a Velux loft conversion take?
It is usually the quickest loft conversion because the roof is not rebuilt, and most work happens inside the loft. Your quote includes a programme for each stage.
What head height do I need for a Velux loft conversion?
As a rule of thumb, around 2.2 metres from the top of the ceiling joists to the underside of the ridge. The new floor and insulation reduce that height, so we measure it carefully at the survey.
Can I have an en-suite in a Velux loft conversion?
Often, yes, if there is enough head height where the shower, basin and WC need to go. Where the waste cannot drain by gravity, a macerator system can be used.
01Loft Conversions
Explore other loft conversion types
Next step
Book Your Free Loft Survey
Tell us about your loft and how you would like to use it. We will measure it, check whether a Velux conversion will work and send you a written, itemised quote.
Send us photos of your loft on WhatsApp to get started, or use our contact form.
- Free survey
- Itemised written quote
- One project manager