Planning permission gets most of the attention. But building regulations are the set of rules that actually govern how your home gets built, and they matter just as much.
Building regulations set the minimum legal standards for construction in England. They cover everything from how strong your foundations need to be, to how much heat your walls are allowed to lose, to where your smoke alarms go. If your build does not meet them, you cannot legally occupy the property. And if you try to sell it later without the right paperwork, you will run into serious problems.
The regulations have also changed significantly in the past few years. If you are planning a new build in London in 2026, you are building to a different set of energy standards than someone who built five years ago. This guide explains how building regulations work, what the main parts cover, how the process runs from start to finish, and what has changed recently. If you have not yet sorted planning permission, our guide to planning permission in London covers that process in full.
Planning Permission vs Building Regulations: What Is the Difference?
These two things get confused regularly, and it is worth being clear about the distinction from the start.
Planning permission controls whether you are allowed to build at all and what the building can look like from the outside. It is concerned with the impact of your development on the surrounding area: scale, appearance, neighbour amenity, and so on.
Building regulations control how the building is constructed. They are about safety, health, energy performance, and the technical standards of the build itself. They apply whether or not planning permission is required.
You can have planning permission without building regulations approval, and you can need building regulations approval for work that does not need planning permission. On a new build you will almost always need both, and they run as parallel processes managed by different people.
A common mistake is treating building regulations as something to deal with after planning. In practice, your architect and structural engineer should be designing to building regulations standards from day one. Retrofitting compliance at the end is expensive and sometimes impossible.
What Are the Approved Documents?
Building regulations in England are published as a series of Approved Documents, each covering a specific aspect of construction. You do not have to follow these documents to the letter; they are guidance rather than law. But if you depart from them, you need to demonstrate an alternative way of achieving compliance, which in practice means more work and more risk. Most builds follow the Approved Documents closely.
Here is what the main ones cover and why they matter for a new build:
| Part | What It Covers | Why It Matters for Your Build |
| Part A | Structure | Foundations, walls, beams, and floors must be strong enough to carry the loads placed on them safely |
| Part B | Fire safety | Escape routes, fire doors, smoke and heat alarms, compartmentation between dwellings |
| Part C | Site preparation and damp | Damp proof membranes, ground contamination, resistance to moisture from the ground |
| Part E | Sound | Sound insulation between dwellings and between rooms, especially relevant for terraced builds |
| Part F | Ventilation | Fresh air supply, extract ventilation in kitchens and bathrooms, airtightness |
| Part G | Sanitation and water efficiency | Toilets, baths, showers, hot water systems, water consumption limits |
| Part H | Drainage | Foul water drainage, surface water drainage, connection to sewers |
| Part K | Protection from falling | Stairs, balustrades, guarding, roof access and protection |
| Part L | Energy efficiency | Insulation, air tightness, heating systems, CO2 emissions targets |
| Part M | Accessibility | Step-free access, door widths, WC provision at ground floor level |
| Part O | Overheating | Limiting solar gain and providing adequate cooling in a more airtight home |
| Part P | Electrical safety | Design and installation of electrical systems |
| Part Q | Security | Locks, hinges, and glazing to resist unauthorised entry |
| Part S | EV charging | Electric vehicle charging point provision for new homes |
Not every part will be relevant to every build, but for a new dwelling in London, most of them will come into play at some stage.
What Has Changed in 2025 and 2026?
This is the area that catches the most people out, particularly those who built or extended a property a few years ago and assume the rules are the same.
They are not.
Energy efficiency: Part L and the Future Homes Standard
The biggest change in recent years is to Part L, which governs energy efficiency. New homes built from 2025 onwards must produce approximately 75 to 80% less carbon dioxide than those built under the 2013 regulations. That is a significant jump.
In practice this means much better insulation throughout the building envelope, higher performance windows and doors, much tighter airtightness standards, and in most cases a low carbon heating system rather than a gas boiler. Air source heat pumps have become the standard heating solution for new builds in London, and the design of the home needs to accommodate them from the start rather than as an afterthought.
Solar panels are increasingly expected, and the Building Regulations etc. (Amendment) (England) Regulations 2026, published in March this year, introduced a new requirement for on-site renewable electricity generation when a new dwelling is constructed. This brings the Future Homes Standard into force in stages, with full implementation expected to come into effect from March 2027.
If you are at early design stage, make sure your architect and mechanical engineer are designing to the current Part L standards, not to what was required three or five years ago. The gap is large and catching up is costly.
Overheating: Part O
Part O was introduced in 2022 and is still relatively new in practice. It applies to all new residential buildings and requires designers to demonstrate that the home will not overheat in a warming climate.
This is more relevant than it sounds. A home built to today’s airtightness and insulation standards retains heat very effectively, which is great in winter and a significant problem in summer. Part O requires a combination of passive measures (limiting solar gain through glazing orientation and sizing) and active measures (opening windows, mechanical ventilation) to keep internal temperatures within acceptable limits.
In London, overheating is taken more seriously than in many other parts of the country. The urban heat island effect means city temperatures are already higher than surrounding areas, and south-facing glazed extensions or rooms with large roof lights can become genuinely uncomfortable without proper design.
Fire safety: Part B
Following the Grenfell Tower fire and the subsequent review of fire safety standards, Part B has been significantly strengthened for higher risk buildings. For new residential buildings over 18 metres in height, a requirement for second staircases comes into force in England on 30 September 2026. This was already a requirement of the Greater London Authority for tall residential buildings in London, so London developers have been working to this standard for some time. If your project is a taller residential development, check the current requirements carefully with your architect and the Building Safety Regulator.
For straightforward single-family new builds, Part B requires a working smoke alarm on every floor, heat alarms in kitchens, interconnected alarms throughout the property, fire doors where required, and clear means of escape from all habitable rooms.
Electric vehicle charging: Part S
All new residential buildings must now include infrastructure for electric vehicle charging. For a single new dwelling with associated parking, this means a dedicated EV charging point. Your electrical design needs to include this from the start, as it requires a dedicated circuit from the consumer unit to the parking space.
How Does the Building Control Process Work?
Building control is the system that checks your build actually complies with building regulations during construction. It runs from before work starts through to completion, and it ends with a completion certificate that you will need to keep safely for the life of the building.
Step 1: Submit a full plans application
For a new build, you will almost always submit a Full Plans application to building control before construction starts. This involves submitting detailed architectural drawings, structural calculations, energy assessments, and specifications for review and formal approval. You can submit to your local authority building control department, or to a private Approved Inspector. The Planning Portal has a list of registered Approved Inspectors if you want to explore the private route.
Private Approved Inspectors are often faster and more responsive than local authority building control, but both routes are legally valid. For most London new builds, the choice comes down to speed, service, and the relationship your contractor has with a particular body.
Step 2: Start on site and notify building control
Before work begins, you must notify building control. From that point, you are responsible for giving adequate notice at each key stage of the build so that inspections can take place. These typically include:
- Commencement of works
- Foundation excavations (before concrete is poured)
- Damp proof course installation
- Oversite concrete or ground floor construction
- Drains (before backfilling)
- Structural frame and roof
- Insulation installation
- Completion
The inspector visits at each notified stage and checks that the work meets the required standard before you cover it up and move on. If they find a problem, they will tell you what needs to be rectified before the next stage can be signed off.
24 to 48 hours notice is typically required before each inspection. Build this into your construction programme and make sure your site manager knows when each notification needs to go in.
Step 3: Final inspection and completion certificate
Once all the work is complete and the final inspection is passed, building control issues a completion certificate. This is one of the most important documents your build produces.
Without it, you cannot legally sell the property. Solicitors acting for buyers will require it. Mortgage lenders will ask for it. If you try to sell a property built without building regulations approval or without a completion certificate, you will face significant delays and legal complications that are expensive and stressful to resolve.
Keep this document securely, alongside your planning consent and any other approvals. If you ever need to sell, remortgage, or make an insurance claim, it will be asked for.
Energy Assessments and SAP Calculations
Every new dwelling in England requires a Standard Assessment Procedure (SAP) calculation to demonstrate compliance with Part L. This is a technical calculation carried out by an accredited energy assessor that models the energy performance of the home. It is used to produce the Energy Performance Certificate (EPC) that every new build must have before it can be occupied or marketed. You can find an accredited SAP assessor through Elmhurst Energy’s search tool.
The SAP calculation needs to be done at two stages. The first is a Design Stage SAP, submitted with your building regulations application to demonstrate that the proposed design will meet the energy targets. The second is an As Built SAP, carried out after construction is complete and reflecting any changes made during the build. The As Built SAP is what produces the final EPC.
In practice this means your architect, mechanical engineer, and SAP assessor need to be working together from the start of the design process. The insulation specification, window sizes and orientations, airtightness target, heating system, and renewable energy provisions all feed into the calculation and cannot be treated in isolation.
Anything Different About London Specifically?
Building regulations are national, so the Approved Documents apply the same way across England. But there are a few things that are particular to London that are worth knowing about.
The London Plan
The London Plan is the strategic planning document for Greater London, produced by the Mayor. It adds requirements on top of national planning policy in several areas that affect building design, most significantly around energy and sustainability. New developments in London are expected to achieve zero carbon on site or offset the remaining emissions through a contribution to the borough’s carbon offset fund. This goes further than national building regulations.
Biodiversity Net Gain
The London Plan also requires developments to achieve a measurable uplift in biodiversity. From April 2024, Biodiversity Net Gain became a mandatory requirement nationally for most planning permissions, requiring a minimum 10% uplift over the pre-development baseline. In London, the Mayor’s guidance pushes for more than the national minimum on larger sites. This affects how your site is designed and landscaped, and you will need an ecological baseline assessment to quantify the gain. Our guide to surveys needed before a new build covers ecological surveys in more detail.
The Building Safety Regulator
The Building Safety Regulator became an independent statutory body in January 2026. For most single-family new builds in London, its direct involvement is limited. But if your project involves a building over 18 metres or seven storeys, you are now working within a more tightly regulated regime that includes the Gateway system: formal checkpoints before you can start work and before you can occupy the building. If your project falls into this category, seek specialist advice from your architect and consult the Building Safety Regulator’s guidance directly.
Common Mistakes Homeowners Make with Building Regulations
These come up regularly in our experience working across London boroughs.
Leaving the energy assessment too late
Some clients treat the SAP calculation as an administrative task to be done near the end of the project. It is not. It is a design tool. If the energy performance of your proposed design is not modelled until late in the process, you may find that you need to make significant and expensive changes to achieve compliance.
Not notifying building control at the right stages
If work is covered up before a building control inspector has signed it off, you may be required to open it up again for inspection at your cost. This is particularly relevant for foundations, drains, and insulation. Make sure whoever is managing the site knows when each notification needs to go in.
Assuming the completion certificate will arrive automatically
It will not. You need to notify building control that the work is complete and request a final inspection. If you move in without doing this, the completion certificate may never be issued, which creates a problem when you come to sell. Chase it before your builder demobilises from site.
Not keeping the paperwork
Completion certificates, energy performance certificates, structural warranties, fire safety documents, and electrical installation certificates all need to be kept for the life of the building. Create a property file from day one and make sure everything goes into it. Future owners and mortgage lenders will need these documents.
Building a New Home in London?
We work across all 33 London boroughs and manage every stage of the build process, including building regulations compliance and building control sign-off. If you want a team that handles this properly so you are not left chasing paperwork at the end, talk to us about your project.
DEVELOPER NOTES
Internal links: /blog/planning-permission-london-guide, /blog/what-surveys-do-you-need-before-a-new-build, /contact
External links: gov.uk Approved Documents, Planning Portal building control, HSE Building Safety Regulator, London Plan (london.gov.uk), Elmhurst Energy SAP assessors
Suggested meta description: Building regulations for new builds in London explained clearly: what the approved documents cover, how building control works, what has changed in 2025 and 2026, and the mistakes to avoid.
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Consider adding a ‘Last updated: June 2026’ note near the top, as the regulatory context is evolving quickly
Frequently Asked Questions
Do I need building regulations approval for a new build in London?
Yes, without exception. Building regulations approval is a legal requirement for all new dwellings. There is no exemption for residential new builds. You must submit an application, have the work inspected at key stages, and receive a completion certificate before the property can legally be occupied.
How long does building regulations approval take?
A Full Plans application must receive a decision within five weeks, or eight weeks if you agree an extension with the building control body. In practice, this is the approval of your submitted drawings. Inspections during the build happen as you notify at each stage. The final completion certificate is issued after the final inspection, typically within a few weeks of the build finishing, provided everything is in order.
Can I use a private building control inspector instead of the council?
Yes. Approved Inspectors are private companies registered with the Construction Industry Council that can carry out building control functions instead of the local authority. They are often faster and more flexible than local authority building control, and the choice is yours. Both routes produce legally equivalent outcomes. A list of registered Approved Inspectors is available through the Planning Portal.
What happens if work does not comply with building regulations?
The local authority has enforcement powers and can require you to alter or remove non-compliant work at your own cost. If you have already moved in or sold the property, you can still face enforcement action. This is why it is important to use a competent contractor, notify building control at the right stages, and not cover up work before it has been inspected.
What is an Energy Performance Certificate and do I need one?
An EPC is a document that rates the energy efficiency of a property on a scale from A to G. All new dwellings must have a valid EPC before they can be sold or rented out. For a new build, the EPC is produced from the As Built SAP calculation. It is a legal requirement, not optional. Your SAP assessor produces it once the build is complete and the final calculations are confirmed.
Does building regulations approval expire?
A building regulations approval does not expire, but the standards it was approved under may become outdated if significant time passes before work starts. If you receive building regulations approval and do not start work for several years, it is worth checking with your building control body whether the approval still reflects current standards, particularly around energy efficiency, which has changed significantly in recent years.
