Loft conversions
Rooflight, rear dormer, L-shaped, hip-to-gable and mansard. Most take 9 to 13 weeks on site, and most families stay at home while we work.
From £42,000 including VAT
Loft types and pricesLofts and rear extensions · Tottenham Hale, N17
Lofts and rear extensions for north London terraces.
We survey, draw, get approval and build, with our own team from a yard in Tottenham Hale. Most of our work is within four miles of it, in N4, N8, N15, N16, N19, N22 and E17.
Survey visits are free and take about an hour. Weekdays, or Saturday mornings.
- Since 1996
- 480 lofts
- 11 people
- Fixed price before we start
- 4.8 from 164 reviews
- Own drawings, own team
What we build
Rear and side-return extensions
Kitchen extensions into the side return or across the back, planned around the drains, the neighbours' walls and the 3 metre rules.
From £68,000 including VAT
Extension types and pricesFive ways into a terrace roof
Which loft you can have depends on the roof you've got, the street you're on and how much room the rules leave. These are the five we build, drawn through a typical Victorian terrace.
Rooflight conversion
Windows set into the existing slope. The roof keeps its shape, so it needs the most height to start with.
FROM £42,000 · 6 TO 8 WEEKS · USUALLY PERMITTED DEVELOPMENT
Rear dormer
The back slope is built out square to make a full-height room. The most common loft on a terrace.
FROM £64,000 · 9 TO 11 WEEKS · USUALLY PERMITTED DEVELOPMENT
L-shaped dormer
A rear dormer plus a second one over the back addition. Room for a double bedroom and a shower room.
FROM £80,000 · 11 TO 13 WEEKS · USUALLY PERMITTED DEVELOPMENT
Hip-to-gable
For end-of-terrace and semi-detached houses with a sloping end. The hip becomes a brick gable, usually with a rear dormer.
FROM £84,000 · 11 TO 14 WEEKS · USUALLY PERMITTED DEVELOPMENT
Mansard
A steep 70 degree slope with a flat roof above, usually at the back. Always needs planning permission.
FROM £108,000 · 14 TO 17 WEEKS · PLANNING PERMISSION
What would yours cost?
Pick your house and the loft you have in mind. The full cost guide adds the bathroom, the stair, the structure and the planning route, and gives a range with build weeks.
A rear dormer on a mid-terrace starts at about £64,000 to £80,000 including VAT, before a bathroom. 9 to 11 weeks on site.
AN ESTIMATE, NOT A QUOTE. WE FIX THE PRICE AFTER A SURVEY VISIT.
Inside the range
- Design, drawings and structural engineer's calculations
- Lawful development certificate or planning application, including the council fee
- Building regulations application and inspections, including the council fee
- Party wall notices drafted and served
- Scaffold, temporary roof and council scaffold licence
- Steels, new floor, insulation, windows and rooflights
- Stair made in our workshop
- Fire doors on the stair and linked mains smoke alarms
Recent work
Six recent jobs, written up with the drawings, the problems we found and what they cost.
BEFOREAFTER
FIG. 1 · Existing roof space and the L-shaped dormer, same section line. Drag the line, use the arrow keys, or press a button.
Weston Park, N8 · L-shaped dormer · 12 weeks on site · £100,000 to £110,000
A main bedroom and shower room for a family of four
Drawn to 38.6 cubic metres against the 40 allowed.
MATTISON ROAD, N4
A side return for a dark galley kitchen
Glass roof on a steel frame, a knock-through and a drain we found before the digger did.
SIDE-RETURN EXTENSION · 14 WEEKS · £92,000 TO £102,000
WALFORD ROAD, N16
A rear mansard, approved first time
Two rooms and a WC at the back of an 1880s terrace, with both party walls raised.
REAR MANSARD · 16 WEEKS · £125,000 TO £140,000
From first call to sign-off
A rear dormer on a terrace, with no planning complications, usually takes six to seven months from the first call to the final certificate. About ten weeks of that is building.
- WEEK 1
Survey visit
An hour in your loft. Written budget estimate within five working days.
- WEEKS 2 TO 5
Design
Measured drawings, a 3D model and two rounds of changes.
- WEEKS 5 TO 13
Approval
Lawful development certificate or planning permission, and building regulations.
- FROM WEEK 5
Party wall notices
Two months' notice to your neighbours, served early so it doesn't hold up the start.
- AROUND WEEK 12
Fixed price
A written price, programme and payment stages. Nothing moves after you sign.
- 9 TO 17 WEEKS
Build
Our own team, the same subcontractors, a note from Jonah every Friday.
- 1 TO 3 WEEKS AFTER
Sign-off
Completion certificate, test certificates and everything in one folder.
The dull bits, done properly
Party walls
If the steels for your loft sit in the party wall, your neighbours are entitled to two months' notice under the Party Wall etc. Act 1996. We draft and serve the notices ourselves as soon as the drawings are settled, so the notice period runs while the council is deciding.
Building regulations
Every loft needs building regulations approval: the structure, the insulation and, above all, a protected escape route down the stair to the front door. We make the full plans application and book every inspection.
The Building Safety Act
Since October 2023, any job with more than one contractor needs a named principal designer and principal contractor. On our jobs that is Niamh and the firm, written into the contract, and we sign the compliance statements at the end.
Pat and Niamh Quinlan
Pat started the firm in 1996 after nine years on London building sites. Niamh joined in 2018 to draw and get approval for everything we build. Between them they see every job from the survey visit to the final certificate, and one of them will be the person who comes to look at your roof.
Niamh drew three versions of the stair before we chose one. The loft was watertight in week four, as the programme said it would be, and Jonah's Friday notes meant I never had to ask where we were.
Maeve, Crouch End N8
Rear dormer with shower room · MARCH 2026
We got three quotes. This was not the lowest, but it was the only one that listed what we would find in the roof and what it might cost. The steel was the surprise they had warned us about.
Daniel, Walthamstow E17
Hip-to-gable and rear dormer · JANUARY 2026
We stayed at home with two children under five. They sealed the landing, swept every evening and rang the neighbours before the chimney breast came out. The bath in the loft is the best decision we made.
Aisha, Stroud Green N4
Rear dormer, bedroom and bathroom · APRIL 2026
Reviews on this concept site are written examples.
Where we work
We keep our jobs within about half an hour of the yard, so Jonah can be on every site every day.
- N4
- Finsbury Park, Stroud Green, the south end of the Harringay Ladder
- N8
- Crouch End, Hornsey, the north end of the Harringay Ladder
- N15
- South Tottenham, West Green, St Ann's
- N16
- Stoke Newington, Stamford Hill
- N17
- Tottenham and Bruce Grove (our own patch)
- N19
- Archway, Tufnell Park, Upper Holloway
- N22
- Wood Green, Noel Park, Bounds Green
- E17
- Walthamstow
Just outside these? Ask. We'll tell you straight away if it's too far for us to run the site properly.
Book a survey visit
An hour in your loft with a tape and a torch, then a written budget estimate within five working days. There's no charge, and nobody will chase you afterwards.