If you’ve never been through the council approval process before, it can feel like a maze — different applications, different timescales, different bodies to deal with, all running alongside the actual business of designing and building your project. The good news is that it follows a fairly predictable sequence, and once you understand what each stage involves and why it exists, it becomes much more manageable.
This guide walks through every step, from defining your project to receiving your completion certificate — including a few things homeowners regularly overlook that cause unnecessary delays.
Step 1: Be Clear About What You’re Actually Building
Before anything is drawn up or submitted, you need a clear, specific picture of what the project involves — not just “a rear extension” but the approximate size, whether any structural walls are coming out, how it will affect neighbouring properties, and what the finished space will be used for.
This matters because different project types trigger different approval routes. A small single-storey rear extension might fall entirely under permitted development. A two-storey side extension almost certainly won’t. Planning rules also vary considerably between London boroughs — what’s permitted without a formal application in one area may require full planning permission in the next. Camden and Islington in North London, for example, have extensive conservation area policies and Article 4 Directions that affect a large proportion of their housing stock. Greenwich in South East London contains a World Heritage Site, which brings its own layer of planning sensitivity. A contractor with genuine local experience will know the landscape and flag potential complications before you’ve spent money on drawings.
Step 2: Understand Permitted Development Rights
Not everything requires a formal planning application. Permitted development rights allow certain types of building work to go ahead without one, provided the project stays within specific size, height, and design limits.
For many homeowners, this is good news. Single-storey rear extensions up to a certain depth, loft conversions with modest dormers, and internal alterations often qualify. However, the rules have important exceptions across London. The Royal Borough of Kensington and Chelsea in West London has removed permitted development rights for basement extensions across the entire borough — meaning any basement project there requires full planning permission regardless of scale. Camden and Islington have similarly wide Article 4 Directions affecting roof alterations in many of their Victorian terraced streets. If you’re unsure, always check with your specific borough rather than assuming the national rules apply.
Even if your project qualifies under permitted development, you can apply for a Lawful Development Certificate — a formal document confirming the work is permitted. It’s not compulsory, but it’s useful evidence for future buyers and mortgage lenders.
Step 3: Get Proper Drawings Prepared
Whether you’re applying for planning permission or just building regulations approval, you’ll need accurate technical drawings produced by an architect or architectural designer. These form the basis of everything that follows — planning assessments, structural calculations, building control submissions, and ultimately the construction itself.
Good drawings include existing layouts, proposed plans, elevations, section drawings, and a site location plan. For building regulations submissions, structural details and specification notes are also required.
Inaccurate or incomplete drawings lead to queries from the council, requests for amendments, and delays. Most professional house building companies work closely with architects throughout and manage this stage as part of the overall project.
Step 4: Submit Your Planning Application (If Required)
If planning permission is needed, the application goes to the local planning department. The council will assess the proposal against national planning policy and local development plans, considering the size and appearance of the proposed structure, impact on neighbouring properties, whether the design is compatible with the surrounding area, and any heritage considerations.
The standard determination period is eight weeks for householder applications, though complex or contentious applications can take longer. Experienced contractors and architects can manage communication with the planning department on your behalf — which is often helpful if the council requests design changes mid-process.
Step 5: Party Wall Agreements — Don’t Skip This
If your project involves work near or on a shared wall, boundary, or structure, the Party Wall etc. Act 1996 may apply. Party wall requirements commonly come into play with loft conversions in terraced or semi-detached properties, extensions built close to the boundary, installation of structural steel beams near a shared wall, and basement excavations.
In the densely built terraced streets typical of inner South London — Lambeth, Southwark, and Lewisham — almost every loft conversion and rear extension will require party wall notices to be served on at least one neighbour. The Act requires you to serve formal notice before work begins. A good building firm will flag this early and either handle it or recommend a specialist party wall surveyor.
Step 6: Building Regulations Approval
This is separate from planning permission and is required for almost all structural construction work. Where planning is about whether you can build, building regulations are about how you build — ensuring the finished structure is safe and fit for purpose. They cover structural stability, fire safety, thermal insulation, ventilation, electrical safety, drainage, and staircase design.
There are two main approval routes. A Full Plans Application involves submitting detailed drawings to building control for review before construction starts — the preferred route for most significant projects because it identifies issues in advance. A Building Notice allows work to start sooner but means inspections happen in real time, which carries more risk if problems emerge on site.
Step 7: Structural Engineering Calculations
For any project involving structural changes — removing load-bearing walls, installing steel beams, extending foundations, or altering the roof structure — an engineer needs to produce structural calculations submitted to building control for approval before work begins.
Reputable building contractors work with structural engineers as a matter of course and will either have established relationships or help you appoint one. This is not optional and cannot be guessed at.
Step 8: Inspections During Construction
Once you’re on site, building control inspectors carry out checks at key stages: foundation excavation, damp-proof course, structural steel installation, insulation, first fix electrical and plumbing, and final completion. These are a legal requirement, and work cannot progress past certain stages until the relevant inspection has been signed off. An experienced contractor will schedule these as part of the build programme so they don’t cause delays.
Step 9: The Completion Certificate
Once the final inspection is passed, building control issues a Completion Certificate, formally confirming the work complies with building regulations. When you come to sell the property, your solicitor will ask for it. Your insurer may want to see it. Mortgage lenders sometimes require it. Without it, work that appears perfectly fine on the surface can become a serious problem at exactly the wrong moment.
The Most Common Mistakes
Starting work before approvals are in place. Building without the necessary approvals can result in enforcement notices, fines, and in serious cases, demolition orders.
Hiring builders who don’t understand the approvals process. A contractor who can’t talk confidently about building regulations, who doesn’t mention party walls, or who suggests skipping inspections to save time is a legal and structural risk.
Underestimating timescales. Planning permission alone takes eight weeks minimum. Add design time, structural calculations, and party wall procedures and you’re looking at several months before a spade goes in the ground. Building this into your programme from the start avoids a lot of frustration.
