A complete guide to what you can build without planning permission — and when you need a Lawful Development Certificate.
Permitted Development Rights (PDRs) allow homeowners to make certain changes to their homes without needing to apply for full planning permission. Many loft conversions in London fall within these rights — meaning faster, cheaper and more certain project approval.
However, PDRs come with specific conditions and limits. Exceeding them, or building in a location where PDRs have been removed, requires full planning permission. Our planning team confirms your specific situation at the free survey — free of charge.
Under Schedule 2, Part 1, Class B of the Town and Country Planning (General Permitted Development) Order 2015 (as amended), a loft conversion is permitted development if all of the following conditions are met:
The additional volume must not exceed 40m³ for a terraced or semi-detached house, or 50m³ for a detached house. Existing additions since July 1948 count toward the total.
No part of the conversion may be higher than the highest part of the existing roof ridge.
Materials used in any exterior works must be similar in appearance to those used in construction of the exterior of the existing house.
No part of the conversion may protrude beyond the plane of the existing roof slope facing a highway.
Any side-facing window must be obscure-glazed and non-opening below 1.7m from the floor of the room in which it is installed.
The conversion must not include any balcony, veranda or raised platform.
Permitted Development Rights under Class B apply to houses only, not to flats, maisonettes or commercial properties. They also do not apply to listed buildings.
Properties within designated conservation areas have had Permitted Development Rights removed or restricted. Most require a full planning application, which our team manages as part of your fixed price.
Some London boroughs have issued Article 4 Directions removing PDRs from specific areas. Our team identifies these at the free survey and advises on the planning approach.
Listed buildings require both planning permission and Listed Building Consent. PDRs do not apply. Prime Loft has specialist expertise in listed building loft conversions across London.
If your proposed conversion would exceed the 40m³ or 50m³ volume limit, a full planning application is required. Our architects can design to maximise permitted volume within PDR limits.
If you own a flat or maisonette — even if in a converted house — PDRs do not apply and full planning permission is required. We handle this as part of your fixed price.
If previous extensions or additions have used some or all of your permitted development allowance, a full application may be required. We check this at the survey.
Even when a loft conversion qualifies as Permitted Development, we always recommend obtaining a Lawful Development Certificate (LDC) from the local authority. This document provides formal written confirmation that the works were lawful at the time of construction.
An LDC is important because: it provides certainty for mortgage lenders and future buyers; it prevents disputes with neighbours or the local authority about the legality of the works; and it is required by most conveyancers when you come to sell your home.
Prime Loft applies for the Lawful Development Certificate on your behalf as part of your fixed price. The application takes approximately 8 weeks and costs a local authority fee of approximately £234. This is included in your quotation.
The best way is to ask our planning team at the free survey — we check this as standard for every property we visit. You can also check with your local authority's planning department or check the planning register for any Article 4 Directions affecting your street or area.
The Planning Portal (planningportal.co.uk) includes a guidance tool, but for definitive confirmation we recommend our planning team assessment at the free survey or a formal Pre-Application Advice request to your local authority.
Some new-build estates have had Permitted Development Rights removed through conditions attached to the original planning permission. Our team checks the planning history of your property at the survey stage.
No. Once issued, a Lawful Development Certificate is a permanent record confirming that the works were lawful at the time they were carried out. It remains valid even if the planning rules subsequently change.
Our planning team confirms your specific planning situation at the free survey — at no charge.
Book Free Survey or call 0208 123 4567Our planning team confirms your permitted development situation at the free survey at no charge.