London's most popular loft type — the full-width rear dormer. Planning or Permitted Development route assessed for your Harrow property, building regulations, structural steelwork and Party Wall notices, all fixed fee.
London's most popular loft type — the full-width rear dormer. Planning or Permitted Development route assessed for your Harrow property, building regulations, structural steelwork and Party Wall notices, all fixed fee.
Housing stock in Harrow: 1930s semi-detached dominates; Edwardian villas in Harrow on the Hill and Pinner; Metropolitan Green Belt in Stanmore and Harrow Weald; post-war flats around Harrow Central.
Character: Outer north-west London suburban; Harrow on the Hill has exceptionally strict heritage controls; rest of borough permissive.
We confirm whether your Harrow rear dormer qualifies for Permitted Development — checking volume limits (40m³ terraced, 50m³ semi/detached), Article 4, conservation area and prior extension history.
If PD applies, we obtain a Lawful Development Certificate for certainty. If not, we submit full planning with Design & Access Statement to Harrow Council.
Full-width flat-roof rear dormer with matching materials, set in from party walls, cheeks clad to match existing roof — the design that Harrow Council approves most readily.
Part B fire escape (protected staircase, fire doors, smoke alarms), Part K staircase, Part L insulation, Part E acoustic separation.
Steel ridge beam, purlin supports, dormer framing, floor joist upgrade — chartered engineer sign-off for Building Control.
Most rear dormers in Harrow's terraced streets trigger Section 6 Party Wall notices. We draft, serve and coordinate the process.
Single planning or regs submission.
Planning + building regs + structural.
Listed, conservation, complex sites.
Direct answers to the questions Harrow homeowners ask every week about rear dormer drawings.
Start a free quote →Most loft conversions in Harrow qualify as Permitted Development under the standard householder allowances — up to 40m³ for terraced or 50m³ for semi-detached, with matching materials and 20cm eaves setback. Flats, properties in conservation areas and listed buildings need full planning. We check eligibility at the free site visit. Full-width rear dormers are the most common PD loft type in Harrow — provided the volume, materials and setback conditions are met. We check every condition before committing to a route.
Our fixed-fee architectural package for a Harrow rear dormer starts at £1,225 (drawings + building regs + structural). Typical build costs in Harrow are £45,000–£70,000 for a standard full-width rear dormer with en-suite, depending on access, floor area and specification.
A full-width rear dormer in Harrow typically adds 15–25 square metres of habitable floor area — enough for a double bedroom with en-suite, or two single bedrooms. The flat roof gives full standing height across the entire width of the house, unlike a rooflight-only conversion which is constrained by the roof pitch.
Rear dormers in Harrow's conservation areas usually need full planning permission because PD rights are restricted. However, because they face the rear (not the street), Harrow Council typically views them more favourably than front dormers or mansards. A well-designed rear dormer with matching materials and sensitive proportions has a strong approval record.
A standard rear dormer in Harrow takes 8–12 weeks to build once on site. Our architectural package takes 3–5 weeks from instruction to submission. Building Control approval adds 2–4 weeks. Total timeline from survey to move-in: approximately 4–5 months.
We cover every London borough with the same fixed-fee approach. If your property sits on a boundary, here are the neighbouring options.
We cover every architectural technology service in Harrow with one chartered team.
From £840. A fixed-fee, end-to-end service — measured survey, scaled drawings, Design & Access Statement where required, Planning P...
From £840. A construction-ready drawing package compliant with every Approved Document — Part A structure, Part B fire, Part L ther...
From £1,225. Every loft type across every {location} roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning ...
From £1,225. The whole spectrum — rear extensions, side returns, wraparounds, double-storey, basement digs. Planning-led design with ...
From £1,575. {location}'s most space-efficient loft solution when PD-route dormers are blocked. Our chartered team designs mansards t...
From £995. Turn your unused {location} garage into a bedroom, home office or open-plan kitchen-diner. Planning route assessment, fu...
From £1,950. Full architectural technology service for basement digs and cellar conversions in {location} — structural underpinning d...
From £350. Chartered structural engineer calculations for every residential intervention in {location} — steel beams, lintels, pad ...
From £450. End-to-end Party Wall Act 1996 service for {location} — Section 1, 3 and 6 notices, schedule of condition surveys, party...
Free quote in 60 seconds. Fixed fee from £1,225. MCIAT chartered.
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