Loft conversion drawings in Islington, £895 fixed

What Islington Council asks of a loft conversion

From the council's Urban Design Guide SPD (January 2017) (adopted January 2017, council page).

• Within conservation areas, proposals for roof extensions anywhere along an unaltered roofline will not generally be acceptable; where the roofline is broken, the scope depends on criteria including the length of the terrace. (source, checked 14 October 2026)
• In conservation areas where it is important to maintain the unbroken roofline on the street frontage it may be acceptable to have a roof extension on the rear roofline, provided the alterations are invisible from the public realm. (source, checked 14 October 2026)
• Where acceptable in principle, roof extensions on residential terraces or villas must be restricted to a single storey. A flat mansard is usually not acceptable in conservation areas. (source, checked 14 October 2026)
• Roof extensions to historic terraces should normally retain the historic parapet form and be set behind it, and raising the brickwork should be avoided; butterfly parapet profiles should be retained where they survive. (source, checked 14 October 2026)
• Party walls should follow the form of the roof and should not include a 90 degree up stand projecting beyond the form of the roof extension. (source, checked 14 October 2026)
• Dormers should generally line up with, and be no wider overall than, the windows immediately below them, and sit a clear distance below the ridge-line, significantly clear of the boundary parapets and above the line of the eaves. (source, checked 14 October 2026)

What Islington loft conversion drawings have to show

Islington's rules separate rear from front, so the drawings show the roofline of the whole street first, whether it is unaltered or already broken, and how much of the proposal can be seen from the public realm. The SPD says that where it is important to maintain the unbroken roofline on the street frontage, a roof extension on the rear roofline may be acceptable if the alterations are invisible from the public realm. Where acceptable in principle, the extension is drawn as a single storey.

On a historic terrace the drawings keep the historic parapet form with the extension set behind it, retain any surviving butterfly parapet profile, and show party walls following the form of the roof, with no 90 degree upstand projecting beyond it. Dormers are drawn lined up with, and no wider overall than, the windows immediately below, a clear distance below the ridge-line, significantly clear of the boundary parapets and above the line of the eaves.

The council's validation requirements ask for neighbouring properties and their windows on every existing and proposed plan, elevation and section, and for a scale bar on every drawing, never marked 'do not scale'. Elevations must annotate the make, type and colour of external materials and how new windows open. Islington has removed householder permitted development rights in 40 of its 42 conservation areas, and its 2017 Urban Design Guide is what the council lists as current, as checked on 14 October 2026.

The national permitted development volume limits (40 cubic metres on a terrace, 50 on a semi-detached or detached house: GPDO 2015, Schedule 2, Part 1, Class B) and the fire escape rules for a new second floor are the same in every borough. They are set out with diagrams on our loft conversion drawings page.

What it costs in Islington

• Planning drawings: £895, plus £548 to Islington Council.
• Certificate of lawfulness where the loft is permitted development: from £950, plus £274 to the council.
• Building regulations drawings: £795.

Loft conversion drawings across London · Islington planning rules · every price