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Harrow, London

Velux loft conversion drawings in Harrow

Velux loft conversion drawings in Harrow cost £695 including VAT. Harrow is a borough of houses: 65.4 per cent of households live in a house or bungalow, and 58.8 per cent own their home. That suits the use of permitted development for a rooflight loft, as long as the address is clear.

From £695 (VAT included)

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  • Fixed fees, VAT included

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    Architectural model of a four-storey London stucco townhouse in its terrace, with a portico, area railings, sash windows, a cornice and chimney stacks
    The house as it stands: four storeys over a lower ground floor.Existing Proposed worksAn illustrative model, built for this page.

    How we work on velux loft conversion drawings

    Nine steps from first call to approval.

    The same model cut through the middle: every floor, the stair, the chimney breasts, the new mansard, rear extension and basement in section
    Section through the model: every floor on one datum.

    1. Enquiry and constraints check

      We check the property against conservation areas, listed status, Article 4 directions, tree preservation orders, flood zone and planning history. We choose the right route and send a fixed quote.

    2. Measured survey

      We survey the house on one datum: rooms, levels, boundaries, drains, trees and the neighbours' windows that the 45° and 25° tests depend on.

    3. Design options

      We model the house in Revit and show you options in 3D and plan, with the planning strategy and the precedents in your street.

    4. Design frozen

      You choose an option in writing. Nothing changes after this without your say.

    5. Independent check

      A second chartered technologist checks every sheet against the council's validation checklist and the policy. A senior review signs it off before anything is submitted.

    6. Submission

      We prepare the forms, certificates, fee and documents and submit through the Planning Portal.

    7. Officer liaison

      We answer the planning officer and make any amendments within five working days, at no charge until approval.

    8. Building regulations

      Technical drawings are coordinated with the structural engineer's calculations, the drainage and the planning conditions.

    9. Approval and hand-over

      Building control approval, then a next-steps pack covering the commencement notice, party wall timing and CIL.

    Free redraws until approval. Every drawing set is checked independently, and the checker is never the person who drew it.

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    Brick cottage with a tiled roof, chimneys and a front dormer window

    Why Harrow suits the rooflight route

    Most Harrow households own their home, and many live in interwar semis. A rooflight conversion leaves the roof shape alone, so there is no volume to count against the allowance and little to argue about with a neighbour. The limit that applies is: Roof alterations (e.g. rooflights) may not protrude more than 0.15 m beyond the roof plane.

    The council's guidance for extensions is the Residential Design Guide SPD. We draw to its principles even where permitted development applies, because it shows what the borough thinks acceptable and keeps the planning fallback open.

    A semi-detached house here averages 663,954 pounds in the latest figures, so a second bathroom or fourth bedroom in the roof is a serious investment, and the drawings are the cheap part of it.

    Harrow owners often ask whether to stop at rooflights or go for a dormer. The honest answer depends on the roof pitch: below a certain height a rooflight room is cramped, and the extra headroom of a dormer pays for itself. We measure first and give you both options on one page, so the choice is made on numbers.

    Rear view of brick terraced houses in London with slate roofs and chimney stacks along the shared roofline

    Local figures for Harrow

    Figures with their unit, period and source
    MeasureValuePeriodSource
    Households living in a house65.4 % of households living in a house or bungalow (detached, semi-detached or terraced)Census 2021nomisweb.co.uk
    Owner-occupied households58.8 % of households owner-occupied (owned outright or with mortgage/loan)Census 2021nomisweb.co.uk
    Conservation areas31 named conservation areas published by the council—planning.data.gov.uk
    Listed building entries295 list entries (Historic England, within the LPA boundary)—planning.data.gov.uk
    Green Belt share of the council area22 % of council area covered by green-belt polygons—planning.data.gov.uk
    Householder decisions917 decisions1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications granted81.7 %1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    Householder applications decided in time93.7 % decided within 8 weeks or an agreed extended period1 July 2025 - 30 June 2026assets.publishing.service.gov.uk
    GPDO Sch 2 Pt 1 Class C, para C.1(b)Roof alterations (e.g. rooflights) may not protrude more than 0.15 m beyond the roof plane—legislation.gov.uk
    Approved Document K 2013, para 1.13, Diagram 1.4Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width)—gov.uk

    A blank value means the figure has not been published, not that there are none. Check your own address with the council.

    Councils bordering Harrow

    Householder applications by street in Harrow

    Streets in Harrow with the most householder applications, and the share approved
    StreetApplicationsApproved
    Headstone Lane3179%
    Norman Crescent2878%
    Albury Drive2675%
    Suffolk Road2576%
    Howberry Road2496%
    Evelyn Drive2284%
    Moss Lane2263%
    Whitchurch Gardens2288%
    Cannonbury Avenue2190%
    Kings Road2153%
    Sylvia Avenue2195%
    Cannon Lane2084%
    Alicia Gardens1988%
    South View Road1961%
    Christchurch Avenue1860%
    Counts of householder applications by street; no individual applications are shown. Streets with fewer than five applications are left out.Source: GLA Planning London Datahub, householder applications, all years held. Contains public sector information licensed under the Open Government Licence v3.0. Contains OS data © Crown copyright and database right 2026.
    Loft enlargement in section: the permitted development limitsExtra roof volume allowed: 40 m³ (terrace house) / 50 m³ (any other house) additional roof volume. Set-back from the eaves: Original eaves maintained; enlargement set at least 0.2 m from the eaves measured up the roof slope, so far as practicable (not required for hip-to-gable or roofs joining a rear/side extension). Height limit: No part higher than the highest part of the existing roofABC

    Loft enlargement in section: the permitted development limits

    A dormer on the rear slope, with the limits that decide whether it needs planning permission.

    A · Extra roof volume allowed
    40 m³ (terrace house) / 50 m³ (any other house) additional roof volume
    B · Set-back from the eaves
    Original eaves maintained; enlargement set at least 0.2 m from the eaves measured up the roof slope, so far as practicable (not required for hip-to-gable or roofs joining a rear/side extension)
    C · Height limit
    No part higher than the highest part of the existing roof

    What to check: conservation, listing and Green Belt

    Harrow has 31 conservation areas and 295 listed entries, and about 22 per cent of its area is covered by Green Belt polygons. A conservation area brings closer scrutiny of roof alterations, an Article 4 direction can remove the rights, and a listed house needs consent for any roof window.

    The Green Belt rarely stops a rooflight but it is a reason to avoid anything that adds bulk to a roof on its edge. We plot your address on all three layers before we quote.

    Heritage in Harrow is concentrated rather than spread evenly, with 4 registered parks and gardens and conservation areas such as Harrow on the Hill. Streets just beyond them can have no controls at all, which is why the address check is worth doing even for a modest scheme.

    Velux loft conversion drawings in Harrow: how householder work is decided

    Harrow decided 917 householder applications in its latest published year and granted 81.7 per cent, with 93.7 per cent decided in time. It is a high-volume borough for house extensions, so officers see roof work often.

    If the roof keeps its rights, a Lawful Development Certificate is a short route. Otherwise the same drawings go to planning drawings in Harrow. Borough figures are not a prediction for your application.

    Harrow also records 461 certificate applications in its latest statistics, so a certificate application is a routine item for its officers and rarely a surprise.

    Headroom, fire and energy under the slope

    Where the stair cannot reach full height, the Approved Document accepts: Loft conversions where 2.0 m cannot be achieved: 1.9 m at the centre of the stair, 1.8 m at the side (half width). A converted loft that becomes a new storey also needs: New storey above 4.5 m by loft conversion: protect the full escape route with fire-resisting doors (min E 20) and partitions (min REI 30).

    The units themselves must meet an energy standard: New elements in existing dwellings, limiting U-values W/(m²·K): roof 0.15, wall 0.18, floor 0.18, windows 1.4 (or WER Band B), doors 1.4. We note the target on the specification so the rooflight you buy will pass the later building regulations drawings in Harrow stage.

    Insulating a sloping ceiling takes height from the room, so the section shows the build-up and the clear height that remains.

    Fees, checks and next steps

    The fixed fee is £695 including VAT, quoted before you commit. A second MCIAT chartered technologist checks every sheet and we redraw free if the council asks for changes.

    If you want more headroom than rooflights give, see dormer loft conversion drawings in Harrow and loft conversion drawings in Harrow. The borough overview is architectural drawings in Harrow; the national guide is Velux loft conversion drawings.

    What you receive

    Planning drawing sheet for a rear extension with plans, elevations and sections
    Sample drawing. Planning drawings for a rear extension: plans, elevations and sections on one sheet set.
    Slate-clad roof extension on a yellow-brick London terraced house
    Storey by storey
    Move up and down — the car travels between floors.

    Other services in Harrow

    Velux loft conversion drawings nearby

    Questions

    Is my Harrow house likely to have permitted development?

    With 65.4 per cent of households in houses, many do. An Article 4 direction or a listing changes that, so we check the address.

    What escape window size is needed?

    Escape window: unobstructed openable area at least 0.33 m², at least 450 mm high and 450 mm wide, bottom of opening no more than 1100 mm above floor.

    How much do the drawings cost?

    From £695 including VAT.

    Can I put windows in a side slope?

    Side roof-slope windows obscure-glazed and non-opening below 1.7 m.

    Sources and dates

    City of London skyline glowing at dusk across the Thames under a dramatic orange sky

    Tell us about your property.

    We check the constraints, then send a fixed fee. Messages before 3pm get a reply the same working day.

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