Finchley is one of the best places in Barnet to add a floor without moving. Church End and Finchley Central (N3) are built up with Victorian and Edwardian houses, West and North Finchley (N12) are dominated by 1920s and 1930s family homes, and East Finchley (N2) has streets of 19th-century terraces running up to the edge of Hampstead Garden Suburb. Most of these houses have a roof void that can take a double bedroom and a shower room, and for many Finchley families converting the loft is a more practical way to gain space than moving within N3 or N12.
The catch is that Finchley is not one planning picture. Most 1930s semis in N12 can take a rear dormer or a hip-to-gable under permitted development, while a house inside the Finchley Church End, Finchley Garden Village or Moss Hall Crescent conservation areas needs planning permission for almost any roof change, even a rooflight. This page sets out which loft suits which Finchley house, what Barnet Council's own design guidance says about dormers, and what the job typically costs, so you can talk to a specialist knowing what is realistic for your road.
Homes in Finchley and the loft that suits them
The right loft is decided by the roof you already have. These are the house types that make up most of Finchley, where you find them, and the conversion that usually gives the best room for the money.
Victorian and Edwardian terraces with a rear outrigger
Where: Church End and Finchley Central (N3), including the Elm Park estate roads off Nether Street laid out from the 1880s; the County Roads east of East Finchley High Road (N2)
Best loft: L-shaped dormer, or a rear dormer on the main roof
The two-storey back addition is what makes these houses work: an L-shaped dormer runs across the main roof and over the outrigger to give a double bedroom plus a bathroom. Where it needs planning, Barnet's guidance limits the outrigger dormer to 50% of the outrigger's depth and wants it set 0.5 m below the main ridge. A terrace shares walls on both sides, so party wall notices go to two neighbours.
Read more: L-shaped dormer, Rear dormer · Price this loft
1920s and 1930s hipped-roof semis
Where: West Finchley and North Finchley (N12), for example the 1930s streets around Friary Park and Lyndhurst Avenue
Best loft: Hip-to-gable plus rear dormer
A hipped roof slopes in at the side, so on its own it gives a narrow, pinched loft. Building the side up to a full gable and adding a rear dormer is the classic Finchley semi conversion: one large double bedroom, an en-suite and a proper staircase over the existing one. Barnet's guidance confirms an original hipped roof can usually be converted to a gable under permitted development.
Read more: Hip-to-gable, Rear dormer · Price this loft
Gable-ended semis and short terraces
Where: Mixed in with hipped semis on interwar streets across N3, N12 and N2 (check your own roof shape)
Best loft: Rear dormer
With a gable already in place the full roof width is usable, so a straightforward rear dormer delivers a large room without touching the side of the house. This is usually the simplest and best-value Finchley loft, and most fall within permitted development volume limits of 50 cubic metres for a semi.
Read more: Rear dormer · Price this loft
Large Edwardian detached and semi-detached houses
Where: Around Woodside Park Road (N12) and the larger roads of Church End
Best loft: Rear dormer or L-shaped dormer, sometimes a hip-to-gable
Big roofs give generous head height, but Barnet asks for wider set-ins or smaller, spaced dormers on larger roof slopes and prominent houses so the dormer stays visually subordinate. Expect more design time and, often, a planning application rather than permitted development.
Read more: Rear dormer, L-shaped dormer, Hip-to-gable · Price this loft
Period houses converted into flats
Where: Common in the Victorian roads of N3 and N2, and most of the twelve villas on Moss Hall Crescent
Best loft: Rear dormer or mansard, with full planning permission
Householder permitted development rights do not apply to flats, so any roof extension to a converted house needs full planning permission, plus consent from the freeholder and usually the other leaseholders. These are viable projects but they take longer to set up.
Read more: Rear dormer, Mansard · Price this loft
Garden-village and Suburb houses
Where: Finchley Garden Village (Village Road, 51 houses first developed from 1909) and the Hampstead Garden Suburb edge of N2
Best loft: Conservation rooflights, or a small, carefully detailed rear dormer
Both are conservation areas with Article 4 directions, so even rooflights need consent. In Hampstead Garden Suburb you also need separate written consent from the Hampstead Garden Suburb Trust, which is not the same as Barnet planning permission.
Read more: Velux / rooflight, Rear dormer · Price this loft
Loft conversion types and prices in Finchley
Five loft types cover almost every Finchley house. The bands below are typical all-in build prices for the area (structure, insulation, electrics, plumbing, plastering, decoration and Building Control sign-off), before furniture.
| Loft type | Typical cost | On site | Planning |
|---|---|---|---|
| Velux / rooflight | £18–30k | 4–6 weeks | Usually PD (not where Article 4 applies) |
| Rear dormer | £30–50k | 8–10 weeks | Usually PD outside conservation areas |
| Hip-to-gable | £35–55k | 8–12 weeks | Often PD |
| L-shaped dormer | £40–60k | 10–14 weeks | Planning likely |
| Mansard | £50–75k+ | 12–16 weeks | Planning required |
| Hip-to-gable + rear dormer | £45–65k | Typical band for the combined job on a hipped semi | |
| Loft + single-storey rear extension | £45–75k for the extension | Priced separately and added to the loft figure | |
Typical Finchley jobs
| Job | Typical band |
|---|---|
| Rear dormer, gable-ended 1930s semi or short terrace (N12) | £30–50k |
| Hip-to-gable only, hipped 1930s semi | £35–55k |
| Hip-to-gable plus rear dormer, hipped 1930s semi | £45–65k |
| L-shaped dormer, Victorian or Edwardian terrace with outrigger (N3, N2) | £40–60k |
| Mansard, period terrace or converted flat (full planning) | £50–75k+ |
| Rooflight conversion, conservation-area roof | £18–30k |
Finchley lofts are priced like the rest of inner Barnet, but a few local factors move the number. Many streets near Finchley Central, North Finchley and East Finchley are in controlled parking zones, so a skip usually needs a parking bay suspension first, and scaffolding on the pavement needs its own highways licence. Conservation-area schemes add drawing time, a planning fee and better materials such as lead-clad dormer cheeks or slate. Period houses can hide surprises like a chimney breast that needs supporting or an old water tank, which a good survey prices up front. The single most common gap between Finchley quotes is VAT, so always ask whether a figure includes it.
For what pushes a job to the top or bottom of its band, see the loft conversion cost guide.
Planning a loft in Finchley
Barnet Council decides planning for all of Finchley. Outside conservation areas, most rear dormers and hip-to-gable conversions on houses are permitted development, provided they stay within the national limits: no more than 40 cubic metres of extra roof space on a terrace or 50 cubic metres on a semi or detached house, nothing higher than the existing ridge, no extension on the roof slope facing the road, materials similar in appearance to the house, and side-facing windows obscure-glazed and fixed below 1.7 m. Because permitted development is judged on the facts, the safe route is a Lawful Development Certificate from Barnet before work starts, which proves the loft was lawful when you come to sell. Anything outside those limits, including most mansards, any front dormer and any roof extension to a flat, needs a householder or full planning application.
Conservation areas in and around Finchley
- Finchley Church End. Covers the Edwardian shopping parades at the junction of Regents Park Road and Hendon Lane, the school, church and houses on Hendon Lane, and Avenue House and its grounds on East End Road. Roof extensions to houses are not permitted development in any conservation area, so a dormer here needs planning permission, and an Article 4 direction covering seven mapped parts of the conservation area also removes permitted development for other roof alterations such as rooflights.
- Finchley Garden Village. A tightly drawn area of 51 houses on Village Road, between Hendon Lane and the Dollis Brook, developed from 1909. Its Article 4 direction removes permitted development for enlargements and any other roof alteration, and Barnet publishes specific design guidance for the village, so loft schemes here are typically limited to conservation rooflights or modest rear dormers designed to that guidance.
- Moss Hall Crescent. Twelve Victorian villas behind a green on the west side of Ballards Lane, south of Tally Ho Corner. Most are now flats, offices or a nursery, and an Article 4 direction removes roof and enlargement rights, so any loft work needs planning permission and a design that respects the villas' original roofline.
- Hampstead Garden Suburb (N2 edge). The whole Suburb is a conservation area with an Article 4 direction, so permitted development does not apply. The Hampstead Garden Suburb Trust also has to consent to any external change, and to loft conversions specifically, separately from Barnet planning permission. Large box dormers are among the changes the Trust highlights as unsympathetic.
Article 4 directions
Barnet has made Article 4 directions in all three Finchley conservation areas. In Finchley Church End, Finchley Garden Village and Moss Hall Crescent they withdraw the permitted development classes for enlargement or alteration of a house (Class A), any other alteration to the roof (Class C, which covers rooflights), chimneys and flues (Class G) and, in Garden Village and Moss Hall Crescent, solar panels. Dormers and hip-to-gables (Class B) already need planning in a conservation area, so the practical effect of Article 4 is that even a rooflight-only loft needs an application. The Church End direction applies to seven mapped parts of the conservation area rather than every property, so check your address on the council's Article 4 maps before assuming either way.
What Barnet Council looks for
- Barnet's Sustainable Design and Development Guidance SPD (Part 4, Residential Extensions and Alterations) is what officers use when a loft needs planning. Where a rear dormer is not permitted development, it should be set in at least 0.5 m from the eaves, the ridge and the edges of the original roof.
- On larger houses, extended roofs or prominent corner plots the SPD asks for bigger set-ins or smaller, spaced dormers. If a dormer is not set down from the ridge for headroom reasons, Barnet asks for a section drawing showing the internal ceiling heights.
- Front dormers will generally not be supported, except on streets where they are already a common feature and would not unbalance the neighbouring houses.
- Hip-to-gable conversions that are not permitted development are generally acceptable where they re-balance a pair of semis (the attached house already has a gable) or a short terrace whose end house already has one.
- Side dormers should be set at least 0.5 m up from the eaves, must not wrap round the hips, and must be obscure-glazed to 1.7 m above floor level. L-shaped dormers over an outrigger, if not permitted development, should cover no more than 50% of the outrigger depth and sit at least 0.5 m below the main ridge.
- Dormer cheeks should be finished in lead, tiles, slate or similar traditional materials, flat dormer roofs in lead or zinc, and roofing felt avoided. In conservation areas, rooflights on the front and rear slopes should be flush-fitting conservation types and not dominate the roof.
More detail in our guides to planning permission in Barnet and loft planning permission, plus party wall agreements and building regulations, which apply even when planning does not. Not sure where your house stands? Run it through the can my loft be converted checker.
Local things to plan for in Finchley
- Skips and parking bays: in a controlled parking zone, Barnet will not issue a skip licence until a parking bay suspension has been approved, and suspension requests need at least 7 working days' notice. The skip company normally applies for the skip licence, but get the bay suspension booked early.
- Scaffold licence: scaffolding that sits on the pavement needs a Barnet highways licence. Builders can apply on your behalf, but the council is clear that the property owner is ultimately responsible for licences being in place. Barnet aims to inspect within 48 hours and issue in three to four working days.
- Party walls: a Finchley terrace has two neighbours and a semi has one, and steels bearing into the party wall or a raised gable on the boundary usually trigger the Party Wall Act. Serve notices early, because the notice period can hold up the start date. See our party wall guide.
- Head height: many Edwardian roofs in N3 are steep enough for a good room, while some 1930s roofs in N12 are shallower. As a rough check, measure from the top of the ceiling joists to the underside of the ridge; around 2.2 m or more is a comfortable starting point. Our loft checker walks you through it.
- Flats and leaseholds: in the many period houses split into flats, a loft needs full planning plus freeholder consent, and often a lease variation. Budget for the legal side as well as the build.
- Materials in conservation areas: Barnet expects lead or zinc on flat dormer roofs and traditional cladding on dormer cheeks, and conservation rooflights fitted flush. These cost more than felt and uPVC, so make sure quotes for Church End, Garden Village or Suburb houses are priced to that spec.
How long a Finchley loft takes
For a typical N12 semi on the permitted development route, allow a few weeks for the survey, drawings and structural calculations, then about eight weeks for a Lawful Development Certificate decision, which you can run alongside party wall notices (one or two months' notice depending on the work). Once on site, a rear dormer usually takes 8–10 weeks, a hip-to-gable 8–12 weeks, an L-shaped dormer 10–14 weeks and a mansard 12–16 weeks, ending with Building Control sign-off and a completion certificate. In a Finchley conservation area, or for a flat, add the eight-week householder planning period and time to revise drawings if officers ask for changes, and in Hampstead Garden Suburb add Trust consent on top.
The loft conversion process guide walks through each stage, from the first survey to the completion certificate.
How Herts Build works
Herts Build is a referral service, not a builder. We make one introduction, chosen for the job, not your details sold to five firms. The specialists we work with handle dormers, hip-to-gables and mansards end to end: drawings, the structural engineer, planning or a Lawful Development Certificate, Building Control and the build itself.
- Tell us about your loft. A few quick questions about your house, roof, budget and timing, about 60 seconds.
- We choose one specialist. Matched to your house type, the loft you need and your part of Finchley.
- They survey and quote. A free visit to measure up and price the job properly. Your contract is with them, directly.
Loft conversion questions from Finchley
Do I need planning permission for a loft conversion in Finchley?
Usually not for a house outside a conservation area. Most rear dormers and hip-to-gables on Finchley semis and terraces are permitted development if they stay within 40 cubic metres (terrace) or 50 cubic metres (semi or detached), do not rise above the ridge and do not face the road. A Lawful Development Certificate from Barnet confirms it. You do need planning in the Finchley Church End, Finchley Garden Village and Moss Hall Crescent conservation areas, in Hampstead Garden Suburb, for a flat, and for most mansards. See our Barnet planning guide.
Which Finchley streets are in a conservation area?
Barnet lists three conservation areas in Finchley itself: Finchley Church End (around the Regents Park Road and Hendon Lane junction, Hendon Lane and Avenue House on East End Road), Finchley Garden Village (Village Road, off Hendon Lane) and Moss Hall Crescent (on Ballards Lane south of Tally Ho Corner). Parts of N2 fall within Hampstead Garden Suburb. Barnet publishes a boundary map for each, so check your address before you commission drawings.
Can I add Velux windows to a loft in a Finchley conservation area?
Not without planning permission in most cases. The Article 4 directions in all three Finchley conservation areas remove permitted development for other alterations to the roof, which covers rooflights. Barnet's guidance says rooflights on conservation-area houses should be flush-fitting conservation types and should not dominate the roof. A rooflight conversion typically costs £18–30k.
What does a hip-to-gable loft conversion cost on a Finchley semi?
A hip-to-gable on its own is typically £35–55k. Most Finchley 1930s semis combine it with a rear dormer for a full-width room, which commonly lands at £45–65k including an en-suite. Check whether each quote includes VAT, as that is the most common omission. Full breakdowns are in our loft cost guide.
My neighbour has not converted. Will Barnet accept a hip-to-gable on my semi?
If your roof is original, a hip-to-gable can usually go ahead as permitted development without a planning decision. Where planning is needed, Barnet's guidance says hip-to-gables are generally acceptable when they re-balance a pair whose attached house already has a gable. If yours would be the first in the pair, officers judge it on the street and the design, so it is worth checking the permitted development route first.
Can I convert the loft of a flat in Finchley?
Yes, but it is a bigger undertaking. Flats have no householder permitted development rights, so you need full planning permission from Barnet, plus consent from the freeholder and often the other leaseholders and a lease variation to take in the roof space. It suits top-floor flats in the large Victorian and Edwardian houses of N3 and N2, typically as a rear dormer or mansard.
How long does a loft conversion in Finchley take?
Plan on three to five months from first survey to finished room for a permitted development dormer: a few weeks of design, around eight weeks for the Lawful Development Certificate and party wall notices, then 8–10 weeks on site. Conservation-area and flat schemes take longer because of the planning application, and Hampstead Garden Suburb also needs Trust consent.