Every loft type across every Harrow roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning route, building regulations, structural calculations and party wall notices, all fixed price.
A loft conversion drawings package in Harrow, where the stock is largely 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, is the full measured-survey-to-submission drawing set London Borough of Harrow needs in order to determine an application: existing and proposed plans, elevations and sections at 1:100 and 1:50, a location and site plan, and the supporting statements the case officer asks for.
Prepared and reviewed by the chartered technologist team at Architectural Drawings London — MCIAT chartered, £2m PI insured.Last reviewed 2026-08-03.


Every loft type across every Harrow roof line — dormer, mansard, hip-to-gable, L-shape, Velux. LDC or full planning route, building regulations, structural calculations and party wall notices, all fixed price.
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 before quoting whether your Harrow loft has the head height and structural capacity.
Most Harrow loft conversions qualify for a Lawful Development Certificate. We check Article 4 and conservation constraints first.
Option studies including massing, internal layout and roof geometry.
Staircase Part K compliance, Part B fire escape, Part L insulation, Part E acoustic separation.
Ridge beam, purlins, steelwork, floor joist upgrade, dormer framing — chartered engineer sign-off.
Almost every Harrow loft triggers Party Wall notices. We draft notices and coordinate with surveyors.

Single planning or regs submission.
Planning + building regs + structural.
Listed, conservation, complex sites.
Move the controls for an indicative figure. It anchors your budget — it is not a quote. Every project is priced after a free survey.
Build costs are separate and quoted by your contractor. See our published fees.
Every Harrow postcode district we draw in, the stock that dominates it and the authority that validates a loft conversion there. Harrow fees below are the statutory England rates for 2026, not loft conversion estimates.
| Postcode | Area | Dominant stock | What it means for a loft conversion |
|---|---|---|---|
| HA1 | Harrow / Harrow on the Hill | Georgian and Victorian houses, listed buildings | HA1 covers Harrow / Harrow on the Hill only; Harrow Council handles the loft conversion, and Harrow / Harrow on the Hill case officers apply the HA1 conservation-area map. |
| HA2 | North Harrow / South Harrow | 1930s semi-detached | HA2 covers North Harrow / South Harrow only; Harrow Council handles the loft conversion, and North Harrow / South Harrow case officers apply the HA2 conservation-area map. |
| HA3 | Harrow Weald / Kenton / Wealdstone | 1930s semi-detached | Harrow Weald / Kenton / Wealdstone sits wholly inside HA3, so Harrow Council validates every loft conversion submitted from an HA3 address. |
| HA7 | Stanmore | 1930s semi-detached, Edwardian villas | A loft conversion at an HA7 address in Stanmore is determined by Harrow Council under its own Local Plan policies for Stanmore. |
| HA5 | Pinner / Eastcote | Tudor fragments, Edwardian villas, 1930s semi-detached | A loft conversion in Pinner / Eastcote may land with Hillingdon Council or Harrow Council — HA5 crosses the boundary, and the HA5 policies map decides it street by street. |
Roof pitch, wall build-up and plot depth change every few Harrow streets, and each one changes what a loft conversion can achieve at that address.
Harrow conservation designations: there are 29 across Harrow Council, Pinner Village, Stanmore, Harrow Weald among them. Designation costs a Harrow owner the permitted-development route: a loft conversion then needs a £548 householder application over 8 weeks, in place of the £249 prior approval route that takes 6 weeks. Stanmore is the Harrow designation that most often changes a loft conversion design.
No blanket Article 4 over Harrow: Harrow Council has not withdrawn permitted development across Harrow, so a loft conversion outside a Harrow conservation area usually keeps it. The £274 Lawful Development Certificate is still the document a HA1 owner wants on file.
What Harrow is built from: 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. Outer north-west London suburban; Harrow on the Hill has exceptionally strict heritage controls; rest of borough permissive. That mix decides the loft conversion route in Harrow more than the postcode does, and it is what a Harrow Council case officer reads first. A householder application costs £548 paid to Harrow Council direct, with 8 weeks to a decision once validated.
Sources for this Harrow loft conversion 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.
Of 84 lawful development certificate appeals decided in Harrow over the window covering appeals decided 2016-2026, an appeal against Harrow succeeded more often than the London norm — 44.0% against 37.5% city-wide. 37 were allowed and 44 dismissed, with 3 split. Most loft conversions run under permitted development and end in a certificate of lawfulness, not a permission. These 84 are the Harrow cases where the council disputed that the work was permitted at all.
Half of those Harrow appeals took more than 174 days to decide from the day the appeal started — time added on top of the council's own determination period, which is the argument for getting the application right first. 100.0% were decided by written representations rather than a hearing or inquiry, meaning the written case and the drawings were the whole of the evidence.
84 lawful development certificate appeals decided in Harrow. Source: Planning Inspectorate casework, OGL v3.0.
Direct answers to the questions Harrow homeowners ask every week about loft conversion 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.
Two costs matter for a Harrow loft: our architectural package (planning route, building regulations and structural calculations, quoted as one fixed figure) and the builder's construction cost, which varies with loft type — a standard dormer is materially cheaper to build than a mansard. We quote the design fee up front; see our fees.
Mansards in Harrow are less common historically — Harrow Council considers each application on its merits. Rear mansards on suitable terraced or semi-detached properties, matching the roofscape, have a reasonable approval rate with the right design and supporting heritage commentary where relevant.
2.3m measured from existing ceiling joist to existing ridge is the practical minimum for a standard conversion in Harrow. Below 2.2m usually requires dropping the ceiling below (reducing rooms on the floor beneath) or redesigning as a mansard.
Most Harrow loft conversions trigger Party Wall Act notices — legal notices to all adjoining owners. Rear dormers can also prompt right-to-light considerations in dense terraced streets, particularly in Harrow on the Hill. We handle both processes.
Harrow's 1930s semi-detached dominates stock lends itself to rear dormers (most common), hip-to-gable (semi-detached), and mansard (period terraces and conservation contexts). Velux-only conversions are possible where ridge height allows. We recommend the best structural and planning route at survey.
We cover all Harrow postcodes — HA1, HA2, HA3, HA5, HA7, HA8 — with surveyors based locally. Survey appointments within 3 working days. Our structural engineer is London-based and attends site when required.
Most Harrow loft conversions require Party Wall notices to adjoining neighbours — typically for steel beam installation and/or raising the party wall. We can co-ordinate the notice process; our in-house engineer handles the structural element. The Act gives neighbours 14 days to respond.

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