Mansard Roof Extensions · NW11 Golders Green
Fixed-fee mansard roof extensions for Golders Green, Hampstead Garden Suburb, Temple Fortune in the NW11 postcode, drawn by an MCIAT-chartered architectural technologist and submitted to Barnet Council. Hampstead Garden Suburb is a nationally important conservation area governed by the Suburb Trust scheme of management as well as Barnet planning.
MCIAT chartered drawings for planning, building regs, lofts and extensions — fixed fees 30% below typical London architects. Tell us what you need and we’ll reply the same working day.
A mansard roof extension adds a full storey behind a new sloping front face — a strong option on NW11's terraces in Golders Green where a standard dormer is too small. Barnet Council scrutinises mansards on townscape and precedent, especially within Hampstead Garden Suburb (one of the largest and strictest in the country); we design to the borough's roof guidance with a Heritage Statement where the setting requires it.
Golders Green's most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards that get approved in Golders Green conservation areas — with heritage statements and planning officer negotiation built in.
Across Golders Green, Hampstead Garden Suburb, Temple Fortune in NW11, the dominant property is arts-and-crafts and inter-war detached and semi-detached houses, including the planned hampstead garden suburb, plus golders green terraces. That stock shapes what mansard roof extensions looks like here: the right approach for a period terrace differs from a mansion-block flat or a new-build, and Barnet Council judges each on design quality and neighbour impact. We survey the specific Golders Green property, confirm the planning route — Permitted Development, a Lawful Development Certificate, or full planning — and draw a council-ready set tailored to the NW11 streetscape.
Housing stock in NW11: Arts-and-crafts and inter-war detached and semi-detached houses, including the planned Hampstead Garden Suburb, plus Golders Green terraces.
Within the district: Golders Green, Hampstead Garden Suburb, Temple Fortune.
Streets we know in NW11: the Hampstead Garden Suburb roads, Wildwood Road, Meadway and the Temple Fortune parades. Each road has its own building line, boundary treatment and precedent that Barnet Council weighs when assessing a mansard roof extensions scheme.
Conservation areas: Hampstead Garden Suburb (one of the largest and strictest in the country). Inside these, most external work needs full planning and a Heritage Statement.
Getting around NW11: Golders Green on the Northern line, plus bus links to Hampstead and the suburb.
Property values: around £550,000 for a flat and £1.5m-£3m for a Suburb house — a useful gauge of the build value an extension or loft adds in NW11.
Borough character: Suburban outer-London borough; permitted development used heavily; Hampstead Garden Suburb has its own residents' trust with additional design controls.
We check against Barnet Council's mansard design guide and design to match the terrace.
Required for Golders Green's conservation areas — demonstrates the mansard respects character and townscape.
Accurate photomontage showing how the mansard sits alongside neighbours — often decisive at Barnet Council committee.
Mansards invariably trigger Party Wall notices in Golders Green's dense terraced streets. Structural package includes new ridge, tie beams, floor joists.
Full liaison with Barnet Council planning officer, committee representation if called in.
Part L thermal, Part B fire (critical on mansards), Part E acoustic separation.
Single planning or building-regs submission.
Planning + building regs + structural.
Listed, conservation or complex sites.
Exceptionally. The Suburb is one of the country's most tightly controlled conservation areas, and changes are governed by the Hampstead Garden Suburb Trust's scheme of management as well as Barnet planning — so you typically need Trust consent and full planning for external work, hedges and even paint colours. We design to the Suburb's detailed standards and handle both consents.
Yes. The inter-war semis and terraces around Golders Green and Temple Fortune, outside the Suburb, suit rear and side extensions and loft conversions, much of it within Permitted Development confirmed by a Lawful Development Certificate. Inside the Suburb, the Trust and conservation controls apply. We confirm which your address falls under.
Almost always. The Hampstead Garden Suburb Trust holds a scheme of management covering the original houses, so most external alterations need Trust approval in addition to Barnet planning permission. We prepare drawings that satisfy both and advise on sequencing the applications.
Family-house extensions and lofts on the inter-war stock — rear kitchen extensions, side infills and hip-to-gable lofts. With houses ranging widely up to £3m in the Suburb, a properly drawn, consent-ready scheme protects both the approval and the value. We handle the planning and Building Regulations drawings together.
Our fixed fee for mansard roof extensions in Golders Green starts at £1,575 — no hourly billing. With Golders Green property at around £550,000 for a flat and £1.5m-£3m for a Suburb house, the professional drawing fee is a small fraction of the value the work adds to NW11's arts-and-crafts and inter-war detached and semi-detached houses. Barnet Council charges its own statutory application fee on top (currently £258 for a householder planning application, £578 for a full application). We quote the drawings as one fixed price and the free site survey covers every NW11 address.
For a NW11 project across Golders Green, Hampstead Garden Suburb, Temple Fortune, expect roughly 3–4 weeks from instruction to submission: week 1 the measured survey, weeks 2–3 the drawings and your revisions, then validation and the statutory determination by Barnet Council (8 weeks for a householder application). We carry the Golders Green application through every officer query to the decision.
Golders Green (NW11) sits primarily in Barnet, so applications are decided by Barnet Council. Article 4 in force in the borough: No. Conservation areas within NW11 include Hampstead Garden Suburb (one of the largest and strictest in the country), where full planning and a Heritage Statement are required. We confirm the planning route for your exact address before quoting.
Almost always. Any structural work behind mansard roof extensions in Golders Green — new openings, steel beams, loft floors, foundations — needs Building Regulations approval covering structure (Part A), fire escape (Part B) and insulation (Part L), submitted to Barnet Council Building Control or an approved inspector. On NW11's typically terraced and semi-detached stock, a Party Wall notice to adjoining neighbours is normally required before the steelwork. We coordinate both as part of the Complete package.
In value terms, yes. With Golders Green (NW11) property at around £550,000 for a flat and £1.5m-£3m for a Suburb house, a well-designed extension or loft typically returns more than it costs in added floor area and sale value, while our fixed drawing fee from £1,575 keeps the professional cost predictable. The bigger risk is an unapproved or non-compliant scheme — which is why council-ready drawings and a clean Building Control sign-off matter on NW11 homes.
From £840.
From £840.
From £1,225.
From £1,225.
From £995.
From £1,950.
From £350.
From £540.
From £450.
From £1,225.
Pick a slot that suits you. No obligation and no sales pressure — just straight answers on your planning route, fixed fee and timescale.
Every NW11 postcode district we draw in, the stock that dominates it and the authority that validates a mansard roof extension there. NW11 fees below are the statutory England rates for 2026, not mansard roof extension estimates.
| Postcode | Area | Dominant stock | What it means for a mansard roof extension |
|---|---|---|---|
| NW11 | Golders Green / Hampstead Garden Suburb | Arts & Crafts houses, Edwardian villas | A mansard roof extension at an NW11 address in Golders Green / Hampstead Garden Suburb is determined by Barnet Council under its own Local Plan policies for Golders Green / Hampstead Garden Suburb. |
| NW11 | Hampstead Garden Suburb | Arts & Crafts houses, Edwardian villas | Hampstead Garden Suburb sits inside NW11; mansard roof extension proposals here are determined by Barnet Council. |
| NW11 | Golders Green | Edwardian villas, 1930s semi-detached | Golders Green sits inside NW11; mansard roof extension proposals here are determined by Barnet Council. |
| N2 | East Finchley | Edwardian terraces, 1930s semi-detached | Adjoining district to NW11, also inside Barnet for mansard roof extension purposes. |
| N3 | Finchley Central | 1930s semi-detached, Edwardian villas | Adjoining district to NW11, also inside Barnet for mansard roof extension purposes. |
| N11 | New Southgate / Bounds Green | mixed stock | Adjoining district to NW11, also inside Barnet for mansard roof extension purposes. |
| N12 | North Finchley / Woodside Park | 1930s semi-detached, Edwardian villas | Adjoining district to NW11, also inside Barnet for mansard roof extension purposes. |
Roof pitch, wall build-up and plot depth change every few NW11 streets, and each one changes what a mansard roof extension can achieve at that address.
Conservation areas covering NW11 (Golders Green / Hampstead Garden Suburb): Barnet Council runs 20, and Hendon, Golders Green, Monken Hadley are the ones NW11 (Golders Green / Hampstead Garden Suburb) owners meet most. A mansard roof extension inside a NW11 (Golders Green / Hampstead Garden Suburb) conservation area loses permitted development, so the NW11 (Golders Green / Hampstead Garden Suburb) submission is a householder application at £258 decided in 8 weeks — not a £120 prior approval decided in 6 weeks. In Hampstead Garden Suburb a mansard roof extension is judged on the street elevation first.
Article 4 and your NW11 (Golders Green / Hampstead Garden Suburb) mansard roof extension: Barnet Council has made no borough-wide direction, so permitted development for a mansard roof extension in NW11 (Golders Green / Hampstead Garden Suburb) generally survives outside NW11 (Golders Green / Hampstead Garden Suburb) conservation areas and listed curtilages. A Lawful Development Certificate at £129 is how a NW11 owner records that a mansard roof extension was lawful.
The building fabric around NW11 (Golders Green / Hampstead Garden Suburb): 1930s semi-detached dominates; Edwardian villas in Muswell Hill, Finchley; Garden Suburb Arts & Crafts in Hampstead Garden Suburb; post-war flats in Colindale. Suburban outer-London borough; permitted development used heavily; Hampstead Garden Suburb has its own residents' trust with additional design controls. A mansard roof extension in NW11 (Golders Green / Hampstead Garden Suburb) is scoped against that stock first. Our NW11 (Golders Green / Hampstead Garden Suburb) fixed fee starts at £1,575; the £1,750 Complete package runs the NW11 (Golders Green / Hampstead Garden Suburb) scheme through Barnet Council planning and building control in one go.
Sources for this NW11 mansard roof extension page: borough policies maps and conservation-area registers (2025–26), Royal Mail postcode district boundaries, the Town and Country Planning (Fees for Applications) (England) Regulations, the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended, and the Party Wall etc. Act 1996.
Free fixed quote in 60 seconds. From £1,575. MCIAT chartered.
Get my free quote →Or contact us about your project firstBefore you commit, it is worth understanding our fixed-fee pricing and seeing what sets the practice apart. You can browse every service and area to find the right fit, or set up your account to track your project. When you are ready, get a quote for your project — most homeowners have a fee in minutes — or contact us and a chartered technologist will be in touch.
