If you are planning an extension in London or Surrey, the biggest hurdle is rarely the build itself. It is the uncertainty at the start. Homeowners often feel stuck between planning permission, permitted development, and prior approval, with conflicting advice online and vague guidance from people who have not checked the exact property.

This is where a clear route map makes everything feel lighter. At HICL Builders, we help homeowners confirm the correct compliance route early, then deliver the construction as a joined up service. We are a family run, turnkey construction company based in Kingston and New Malden, working across South West London on extensions, renovations, loft conversions, kitchens, bathrooms, and new builds (including HMO projects). The company began in 2000 and rebranded as HICL in 2013, with a vision to be the first choice locally and regionally for high quality domestic and commercial construction.

Our director, Andi Drishti, has nearly 20 years in the industry and is City and Guilds certified, with a strong carpentry background and years of experience interpreting structural plans. Clients often comment on his ability to spot practical solutions that protect the design intent and avoid expensive surprises. Debra supports the business as office manager, keeping communication responsive and organised throughout. Together with our skilled team, we focus on professional conduct, efficiency, reliability, and results that meet the agreed timeframe.

Meet the HICL team.

Planning Permission vs Permitted Development: The Simple 2026 Framework

To reduce stress, it helps to think of extensions in three routes:

Planning permission is the full application route. It is typically needed when your design falls outside permitted development rules, when your home has restrictions, or when the nature of the proposal triggers a planning assessment.

Permitted development is different. It allows many house extensions to proceed without a full planning application, provided you stay within strict national limits and conditions. This route usually applies to houses rather than flats or maisonettes, and it can be restricted or removed in some areas.

Prior approval sits alongside permitted development for certain larger single storey rear extensions. It is a notification process where the council consults neighbours before you build. Many homeowners find this step reassuring because it builds consultation into the process, but it still needs to be handled carefully.

One important point is often missed. Even when planning permission is not required, building regulations approval and party wall duties may still apply. This is why checking early is so valuable. It protects your budget, your timeline, and your future sale proof documentation.

If you want a practical guide to reduce uncertainty before you appoint a builder, this resource is a helpful read.

The Key 2026 Rules Most Homeowners In London And Surrey Need

Most confusion comes from not knowing which measurements and conditions matter. As a starting point, the standard permitted development depth for single storey rear extensions is commonly up to 4 metres for detached houses and up to 3 metres for other houses, subject to conditions. If you want to go beyond those standard depths, the larger home extension route can apply, using prior approval.

In practical terms, prior approval is typically defined as extending beyond the original rear wall by over 4 and up to 8 metres for detached houses, and over 3 and up to 6 metres for other houses. Height rules and boundary conditions still matter, including limits on eaves height when close to boundaries. These details are where many projects get caught out, especially when the initial design is ambitious and the checking happens later.

You are also more likely to need full planning permission if you are adding a two storey element, significantly changing the roofline, building forward of the principal elevation, or creating impacts that fall outside national limits. Even when you believe the work is permitted development, many homeowners choose to apply for a Lawful Development Certificate for certainty, especially if they plan to sell or remortgage. It is a practical way to prove the work was lawful, rather than relying on memory, assumptions, or informal advice.

London And Surrey Watch Outs Plus The Safest Next Steps With HICL Builders

London and Surrey have some common watch outs that can quickly change what is possible. Conservation areas, listed buildings, and locally restricted streets can reduce permitted development rights, sometimes even for works that look minor. Some councils also use Article 4 directions to remove permitted development rights in targeted areas. That is why checking your exact address matters, not just your postcode area.

Neighbours are another key factor. This is not only about keeping relationships smooth, it is procedural under prior approval because neighbour consultation is part of the process for larger rear extensions. If you handle the sequence properly, you reduce the risk of late objections, redesigns, and delays that push your start date back.

The quickest way to avoid wasted design fees is to confirm three items early. First, what your property is classed as, house versus flat or maisonette. Second, whether any restrictions apply, such as conservation status, listing, Article 4, or previous planning conditions. Third, whether your initial concept sits within standard permitted development, needs prior approval, or requires full planning.

From there, HICL Builders can support a practical next step sequence. We start with a measured survey and feasibility review, then help shape an outline layout and massing that aligns to permitted development limits where possible. We can also support early conversations with building control and party wall professionals where needed. If an application is required, we can support prior approval or planning, and advise on a Lawful Development Certificate where appropriate.

Because we are turnkey, you are not coordinating multiple contractors. Our qualified team includes skilled builders, plumbers, NICEIC electricians, carpenters, bricklayers, roofers, plasterers, kitchen and bathroom fitters, and decorators. We provide a detailed quote, contract, and plan of works, plus dedicated customer service before, during, and after the build. We also offer a 5 year guarantee on structural work, free no obligation quotes, and access to trade discounts.

If you want an example of how structured planning and scheduling protect deadlines, this completed HICL project shows the approach in action. With a baby on the way, our team created a clear 3 week schedule and coordinated trades, deliveries, and inspections to stay on track without cutting corners. The same discipline is what makes an extension feel exciting again, rather than stressful paperwork.

View our home extension services page.

FAQs:

Can I build a larger rear extension in 2026 without full planning permission?

In many cases, yes. The prior approval process can allow a larger single storey rear extension within defined limits, subject to neighbour consultation. You still need to meet wider permitted development conditions, and your property must not be restricted by local controls.

Should I get a Lawful Development Certificate?

It is not always required, but it is often sensible. If you want proof for a future sale or remortgage, a Lawful Development Certificate can provide clarity, especially where there is any doubt or where local restrictions create complexity.

Why do London and Surrey homeowners get caught out most often?

The most common issues are assuming permitted development applies to flats and maisonettes, missing restrictions such as conservation status or Article 4 directions, and designing first then checking later. Rear depths, heights near boundaries, and the larger extension rules under prior approval are frequent pressure points.

If you want certainty and a smoother path from concept to completion, HICL Builders can help you confirm the right route early and deliver a high quality build with one accountable team.

Get a free quote: Email office@hiclbuilders.com