020 7131 9703Request a fixed quote
Back of a semi-detached house with a new blockwork extension rising two storeys beside the original first-floor window

Blog: extensions and lofts

How much do double-storey extension drawings cost in London?

By Property Architecture drawing team, chartered architectural technologists (MCIAT). Published . 3 minute read.

Drawings for a double-storey extension to a London house cost £769 drawings + £200 survey (£969 total), and almost all of these projects also need a planning application, for which the council charges £548Ribble Valley Borough Council, guide to the national fee scale from 1 April 2026. A second storey is where the neighbours start to care, so the design time goes into light, overlooking and roof shape as much as into the room itself.

From £969 total, survey included

  • MCIAT chartered
  • £2m PI insured
  • LABC Partnered
  • Fixed fees, no VAT to add

Request a fixed quote

We use it to check conservation areas and constraints.
Pick the council that decides your application.
A few lines: what you want to build, and anything the council has already said.
Add photos or drawings

Drop files here or choose from your device

PDF, JPG, PNG, DWG · up to 10 files, 90 MB in total

    Key takeaways

    What the drawings cost, and what the council charges

    A double-storey extension is the largest householder project we draw, which is why the survey and drawings are £769 drawings + £200 survey (£969 total). The set is larger, because there are two new floors to show, and the structure is more involved. It covers the existing house, the new plans and elevations, and the sections that show how the new roof meets the old.

    The council charges separately. For an extension to a single house the planning fee is £548Ribble Valley Borough Council, guide to the national fee scale from 1 April 2026, due when the application is submitted. A decision is due within 8 weeksTown and Country Planning (Development Management Procedure) (England) Order 2015, article 34, though councils can ask for more time.

    What the job costs: our fee from £969Drawings: £769. Measured survey: £200. National planning fee, extension or alteration to a single house: £548 (paid to others)Drawings£769Measured survey£200National planning fee, extension oralteration to a single house£548Total to us, from £969; other costs are paid direct
    Our fixed fee beside the council's planning fee. The council's fee is paid to the council, not through us.

    Why a second storey almost always needs planning permission

    Permitted development allows a two-storey rear extension only within narrow limits. It may extend no more than 3 metres beyond the rear wall and not within 7 metres of the rear boundaryGeneral Permitted Development Order 2015, Schedule 2, Part 1, Class A. London gardens are often shorter than that allows, which rules the right out before any other test. The upper part must also follow the original roof: the same as the original house so far as practicableGeneral Permitted Development Order 2015, Schedule 2, Part 1, paragraph A.3(c), and any upper-floor window in the side wall must be obscure-glazed, and non-opening unless the opening part is more than 1.7 metres above the floorGeneral Permitted Development Order 2015, Schedule 2, Part 1, paragraph A.3(b).

    In a conservation area the question does not arise, because a rear extension of more than one storey is not permitted development on article 2(3) land, which includes conservation areasGeneral Permitted Development Order 2015, Schedule 2, Part 1, paragraph A.2, and article 2(3). So most London owners apply, and we prepare the application with the planning tests in mind. Our planning drawings explain the route, and our double-storey extension drawings page lists what is in the set.

    Back of a semi-detached house with a single-storey rear extension being built in grey blockwork, with scaffolding alongside
    Adding a floor above an extension changes how it looks from the neighbours' windows, which is what the council weighs. Photo: Brett Jordan, Pexels License

    Where the design time goes

    The extension itself is rarely the hard part. The work is in how it sits against the neighbours: how much it shades their garden, whether the new first-floor windows look into their rooms, and whether the roof matches the house. A second storey that steps in from the boundary, or has no side windows at all, is usually easier to approve than one that fills the plot.

    We draw these relationships on the plans and sections, so the officer can see the answer without having to ask. That is the part of the drawings that saves time, because a clear drawing avoids a request for more information, which stops the decision clock.

    The costs that come with a second storey

    A two-storey extension carries more load, so the steel and foundations are calculated: our structural calculations start from £385. The construction details go in a separate set, building regulations drawings, from £729.

    Where the new walls meet a neighbour's, the Party Wall etc. Act applies: a party structure notice must be served at least two months before the work beginsParty Wall etc. Act 1996, section 3. Our notices start from £45 for each adjoining owner. And the Community Infrastructure Levy has a householder exemption: an owner living in the house as their sole or main residence is exempt from CIL on a residential extensionCommunity Infrastructure Levy Regulations 2010, regulation 42A.

    How the job runs, step by stepFree constraints check of your address and a fixed quote Then: Measured survey of the house and garden Then: Plans, elevations and sections of both new floors drawn Then: Neighbour relationships checked on the drawings Then: Planning application prepared and sent for you Then: Free redraws if the council asks for changesFree constraints check of your addressand a fixed quoteMeasured survey of the house andgardenPlans, elevations and sections of bothnew floors drawnNeighbour relationships checked on thedrawingsPlanning application prepared and sentfor youFree redraws if the council asks forchanges
    From constraints check to a submitted planning application.

    Protecting the budget

    Two habits keep a double-storey project on budget. Fix the footprint and roof shape before you commission the structural work, because changes after the calculations are redrawing costs. And talk to your neighbours early. A neighbour who knows what is coming rarely objects, and an objection is the most common reason for a decision to slip past the eight weeks.

    If the council does ask for changes, we redraw free until the application is approved.

    The figures, with sources

    National planning fee, extension or alteration to a single house
    £548Ribble Valley Borough Council, guide to the national fee scale from 1 April 2026Checked 25 October 2026
    Decision period for an application that is not major development
    8 weeksTown and Country Planning (Development Management Procedure) (England) Order 2015, article 34Checked 25 October 2026
    Permitted development limit for a rear extension of more than one storey
    no more than 3 metres beyond the rear wall and not within 7 metres of the rear boundaryGeneral Permitted Development Order 2015, Schedule 2, Part 1, Class AChecked 25 October 2026
    Rear extensions of more than one storey on article 2(3) land
    not permitted development on article 2(3) land, which includes conservation areasGeneral Permitted Development Order 2015, Schedule 2, Part 1, paragraph A.2, and article 2(3)Checked 25 October 2026
    Roof pitch of a multi-storey enlargement
    the same as the original house so far as practicableGeneral Permitted Development Order 2015, Schedule 2, Part 1, paragraph A.3(c)Checked 25 October 2026
    Upper-floor windows in a side wall
    must be obscure-glazed, and non-opening unless the opening part is more than 1.7 metres above the floorGeneral Permitted Development Order 2015, Schedule 2, Part 1, paragraph A.3(b)Checked 25 October 2026
    Notice for work to a party structure
    a party structure notice must be served at least two months before the work beginsParty Wall etc. Act 1996, section 3Checked 25 October 2026
    CIL exemption for residential extensions
    an owner living in the house as their sole or main residence is exempt from CIL on a residential extensionCommunity Infrastructure Levy Regulations 2010, regulation 42AChecked 25 October 2026

    Questions

    Can a double-storey extension ever be permitted development?

    Only within tight limits on depth and distance from the rear boundary, and never in a conservation area. We check your plot against the limits before quoting, and tell you plainly if a planning application is the right route.

    Do I need a structural engineer as well?

    Yes, the beams and foundations need calculations. Our structural calculations are priced separately, and building control will ask for them.

    Will the neighbours be consulted?

    Yes. Neighbours are notified of a planning application and can comment, and where you share a wall the Party Wall etc. Act requires a separate notice.

    How long do the drawings take?

    Normally about a week after the survey, though a double-storey set is larger than a single-storey one. The council's decision time is separate.

    Header photo: The back of a semi-detached house with a new blockwork extension rising beside the original first-floor windows by Brett Jordan, Pexels License.

    The fixed fee for double-storey extension drawings

    Drawings
    from £769
    Measured survey
    £200
    Total you pay
    from £969
    Council fee
    paid to the council separately

    No VAT to add. The fee is fixed in writing after a free constraints check of your address.

    What you get

    • A measured survey of your house
    • Existing and proposed plans for both floors
    • Elevations and sections showing the new roof
    • Planning application prepared and submitted for you
    • Free redraws until approval
    • More about our double-storey extension drawings
    Request your fixed quoteCall 020 7131 9703
    Red-brick house with a slate roof and roof windows, a low glazed extension on its garden side and a striped lawn in front

    Extensions and lofts

    How much do garden room drawings cost in London?

    A garden room is often allowed without a planning application, but only inside tight rules on height, boundaries and use. Here is what the drawings cost and how to tell which side of the line you are on.

    From £4793 minute read

    Loft bedroom with a pitched ceiling, two roof windows and glazed doors opening onto a small balcony

    Extensions and lofts

    How much do loft conversion drawings cost in London?

    Loft drawings are one fixed fee, but the council's charge, the structure and the party wall add to the bill. Here is what drives each, and how to tell if a loft needs planning at all.

    From £6794 minute read

    Back of a semi-detached house with a single-storey rear extension being built in grey blockwork, with scaffolding beside it

    Extensions and lofts

    How much do rear extension drawings cost in London?

    The drawings for a rear extension cost the same whichever route you take, but the council's charge and the work around it do not. Here is how the route changes the bill.

    From £6794 minute read

    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.

    Request a fixed quoteCall 020 7131 9703WhatsApp