Loft conversion in Southwark: Planning Permission Guide
Everything you need to know about loft conversions in Southwark — permitted development rules, costs, and which professionals you'll need.
Based on 204 decided applications in Southwark over 12 months (188 granted, 16 refused).
Southwark has numerous conservation areas including Borough, Bermondsey, Dulwich Village, Herne Hill, and Peckham Rye. Dulwich Village has a unique Dulwich Estate Scheme of Management layering private controls over standard planning. Article 4 Directions cover many Victorian terraces. Listed buildings are concentrated along the Thames frontage and around Southwark Cathedral. Flood zones apply near the river.
Recent loft conversion decisions in Southwark
The 5 most recent decided applications. Addresses redacted to postcode area.
Construction of an L-shaped rear dormer loft extension including raising the roof ridge by 400mm and installing two rooflights to the fro…
Construction of L-shaped rear dormer extension with Juliet balcony and roof terrace over rear outrigger, raising of roof ridge by 400mm, …
Excavation of basement with rear side infill extension and L-shaped rear dormer extension with 2no. rooflights to the front roof slope
Certificate of lawfulness (proposed) for the construction of an L-shaped rear dormer extension and installation of 2no. rooflights to the…
Loft conversion with rear dormer on main roof and rear side on the outrigger with a terrace area and also raising the ridge by 300mm.
These are borough-wide. See the 5 nearest to your address.
Check your address freePermitted Development Rules
Additions etc to the roof of a dwellinghouse
GPDO 2015, Schedule 2, Part 1, Class B
Loft conversions fall under Part 1, Class B of the GPDO. You can add volume to your roof space without planning permission, as long as you stay within the cubic metre limits for your property type.
Key dimension limits
These are the maximum GPDO limits for a detached house with no constraints. Your actual limits depend on your property type, location, and any planning restrictions.
Enter your postcode to see the personalised limits for your loft conversion.
Check my limitsTypical Costs in London
Loft conversion costs vary significantly depending on the type — a simple Velux conversion is much cheaper than a dormer or mansard.
Cost per m²
construction rate
Typical total
Based on 15–25 m²
Typically includes
Typically excludes
Dormer loft conversions are at the higher end. Velux/rooflight conversions are cheaper. Mansard conversions can exceed these ranges.
Get a personalised cost estimate based on your actual loft conversion dimensions.
Get my estimateWhich Professionals Do You Need?
Loft conversions involve structural alterations to your roof and floor, so professional input is important for safety and Building Regulations compliance.
You'll need a structural engineer and a party wall surveyor for this project.
Loft conversions involve structural alterations and Building Regulations requirements that benefit from professional design.
Typical fee: £2,000–£5,000 (Plans + Building Regs)
Loft conversions require structural calculations for floor strengthening, roof alterations, and any steelwork.
Typical fee: £800–£2,500
Your semi-detached house shares a boundary with neighbours. Extensions and loft work within 3 metres of a shared wall trigger the Party Wall Act.
Typical fee: £700–£1,500 (per neighbour)
This guidance is based on a typical semi-detached house with no special constraints. Listed buildings, conservation areas, and attached properties may require additional professional input.
Find out exactly which professionals you need for your loft conversion.
Get personalised guidanceConservation Areas & Listed Buildings
In conservation areas, dormers on any roof slope facing a highway are not permitted development. Velux or rooflight conversions may still be possible.
Properties in conservation areas often have reduced permitted development rights. Some project types (like side extensions) lose PD rights entirely. An Article 4 Direction can remove additional PD rights.
Listed buildings (Grade I, II*, or II) have no permitted development rights at all. Any external alteration requires Listed Building Consent in addition to any planning permission. An architect experienced in heritage work is essential.
Check if your property is in a conservation area or has other planning constraints.
Check my propertyFrequently Asked Questions
Just want a quick yes/no for your loft conversion?
Run our free 2-minute check to see whether your project likely qualifies as permitted development in Southwark — your address, your constraints, your council's own recent decisions.
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