House Extensions Planning Permission
Planning permission information for House Extensions in London and Hertfordshire
Many single-storey house extensions in England fall under permitted development rights, which means planning permission is not required provided certain limits and conditions are met. Below is a summary of the key rules for house extensions. LCCL Construction assesses whether your project needs planning permission during the initial consultation and manages all planning applications as part of our design and build service.
Permitted Development Rules for House Extensions
Designated Land Restrictions
On designated land, which includes conservation areas, Areas of Outstanding Natural Beauty, National Parks, the Broads and World Heritage Sites, no exterior cladding is permitted. Side extensions are not allowed, and rear extensions of more than one storey are not permitted development. The larger single-storey rear extension allowances (see below) also do not apply on designated land.
50 Percent Land Coverage
No more than half the area of land around the original house can be covered by additions or other buildings. Sheds, outbuildings, garages and any other structures must be included when calculating the 50 percent limit. The term "original house" means the house as it was first built, or as it stood on 1 July 1948 if built before that date. Previous extensions by former owners count towards this limit.
Example of LCCL Construction Design and Build of Dormer Loft Conversion project in London. Approved by Local Planning Authority.
Example of LCCL Construction Design and Build of rear single storey house extension project in East Barnet, London. Approved by Local Planning Authority.
Position Restrictions
No extension is permitted forward of the principal elevation (the front of the house) or forward of any side elevation that fronts a highway.
Materials
Materials used in the extension must be similar in appearance to the existing house, including brickwork, render, roof tiles and windows.
Side Extension Rules
Side extensions must be single storey only. The width of a side extension must not be greater than half the width of the original house. The maximum height is 4 metres, and the maximum eaves height is 3 metres if the extension is within 2 metres of a boundary.
Single-Storey Rear Extension Limits
A single-storey rear extension must not extend beyond the rear wall of the original house by more than 4 metres for a detached house, or 3 metres for any other house type. On land that is not designated and not a Site of Special Scientific Interest, these limits increase to 8 metres for detached houses and 6 metres for all other houses under the larger home extension scheme (a prior approval notification to the local authority is required). The maximum height of any single-storey rear extension is 4 metres.
Height Limits
The maximum eaves and ridge height of any extension must not be higher than the existing house. If the extension is within 2 metres of a boundary, the maximum eaves height is 3 metres.
Flats and Maisonettes
The permitted development allowances described above apply to houses only. They do not apply to flats, maisonettes or other buildings. A full planning application is always required for these property types.
Two-Storey Extension Permitted Development Rules
Two-storey rear extensions can qualify as permitted development provided they meet stricter conditions than single-storey extensions. The extension must not extend beyond the rear wall of the original house by more than 3 metres. The maximum eaves height must not exceed the eaves height of the original house. The roof pitch must match the existing house as far as practicable. No part of the extension can be within 7 metres of the rear boundary. Materials must be similar in appearance to the existing house.
Two-storey side extensions are not permitted development and always require planning permission. Similarly, two-storey extensions on designated land require a full planning application. LCCL Construction’s architects have extensive experience designing two-storey extensions that comply with permitted development rules or securing planning permission where required.
Why Choose LCCL Construction for Your House Extension
LCCL Construction is a design and build company based in Finchley, London N3, specialising in house extensions, loft conversions, renovations and new builds across London and Hertfordshire. With over 20 years of experience, more than 200 verified reviews rated 4.7 out of 5, and LABC Awards Regional Winners 2024 for Best Residential Extension in London, we manage every stage of your house extension from consultation and planning through to construction and completion.
Our in-house architects prepare all planning permission applications and have extensive experience working with local planning authorities across London and Hertfordshire boroughs including Barnet, Enfield, Haringey, Camden, Islington, Hertsmere and St Albans. We assess whether your extension qualifies as permitted development during the initial consultation, and if a full planning application is required, we handle the entire process on your behalf.
Need Planning Advice for Your House Extension?
Book a free consultation call to discuss your house extension project. We will assess your property, confirm whether planning permission is needed, and outline the design and build process from start to finish. Call 020 8037 7332, email info@lcclconstruction.co.uk or book online.
Testimonials
We used LCCL for our extension and the whole team were fantastic from start to finish. The planning process was handled smoothly and the build quality was outstanding. We’ve since used them for our loft conversion too." — Mia M, Google
LCCL Construction delivered our rear extension on time, on budget and to a very high standard. Alex and his team were professional, communicative and a pleasure to work with throughout." — Alex Gray, Google
Frequently Asked Questions
Q1: Do I need planning permission for a single-storey rear extension?
In most cases, no. A single-storey rear extension of up to 4 metres (detached houses) or 3 metres (all other houses) usually falls under permitted development rights. Under the larger home extension scheme, these limits increase to 8 metres and 6 metres respectively on non-designated land, subject to a prior approval notification to the local authority. LCCL Construction assesses this during the initial consultation and confirms whether your specific project qualifies.
Q2: Do I need planning permission for a two-storey extension?
A two-storey rear extension of up to 3 metres can qualify as permitted development, provided it meets conditions including matching the roof pitch, using similar materials, and being at least 7 metres from the rear boundary. Two-storey side extensions always require planning permission. LCCL Construction’s architects design two-storey extensions to comply with permitted development where possible, and manage the full planning application process where permission is required.
Q3: How long does planning permission take for a house extension?
A standard householder planning application typically takes 8 weeks from submission to decision. Prior approval notifications under the larger home extension scheme take 42 days. If your project falls under standard permitted development, you can apply for a Lawful Development Certificate, which usually takes 6 to 8 weeks. LCCL Construction prepares and submits all applications on your behalf as part of our design and build service.
Q4: Can I extend my house if I live in a conservation area?
Yes, but there are additional restrictions. In conservation areas, side extensions are not permitted development, rear extensions of more than one storey require planning permission, and no exterior cladding is allowed. Single-storey rear extensions within the standard limits (4 metres for detached, 3 metres for others) may still qualify as permitted development. Our architects have experience designing extensions that meet conservation area requirements and have achieved planning approvals in conservation areas across London and Hertfordshire.
Q5: What is the larger home extension scheme and how does it work?
The larger home extension scheme allows single-storey rear extensions of up to 8 metres (detached houses) or 6 metres (all other houses) without full planning permission, provided the property is not on designated land or a Site of Special Scientific Interest. It requires a prior approval notification to be submitted to the local authority, who will consult with adjoining neighbours. If no objections are raised within 42 days, the extension can proceed. If neighbours object, the local authority makes a determination. LCCL Construction manages this entire process on your behalf.