Building Regulations
Windows
Doors
Building Regulations for Timber Windows and Doors
Replacing or installing new timber windows and doors isn’t just about design – it’s about meeting the latest UK Building Regulations. Since June 2022, updated requirements for energy efficiency, ventilation, and safety have applied to all replacement glazing and new openings in England.
Whether you’re upgrading sash windows in a conservation area or fitting new French doors in a modern extension, every installation must comply with these standards to ensure your property remains safe, energy-efficient, and legally certified.
What the Building Regulations Cover
Building Regulations exist to protect the safety, efficiency, and accessibility of buildings. When replacing or installing windows and doors, compliance generally covers:
Thermal performance – meeting minimum energy efficiency standards (Part L).
Ventilation – ensuring adequate airflow through trickle vents or other means (Part F).
Fire safety – maintaining escape routes and fire-resistant glazing where required (Part B).
Structural integrity – ensuring the openings and frames are sound (Part A).
Accessibility – suitable thresholds, opening sizes, and ease of use (Part M).
Security – for new dwellings, compliance with Approved Document Q.
Simply replacing the glass does not trigger full compliance, but replacing the entire window or door does.
You Don’t Need to See Ugly Trickle Vents
Ventilation is a key part of Building Regulations, but that doesn’t mean you have to spoil the appearance of your windows or doors with visible plastic vents.
At Sash Window Shop, we offer discreet and concealed trickle vent options built into the frame or head of the window, keeping your installation compliant with Part F (Ventilation) while preserving the clean lines of your design.
This option is available across our entire product range – including sash windows, casement windows, and doors – providing an elegant, regulation-compliant solution for both period and contemporary properties.
Key Building Regulation Requirements for Sash Windows
Replacement sash windows must meet the following:
Maintain or improve existing compliance – do not make safety or performance worse.
U-value limits for energy efficiency:
England & Wales: Max 1.4 W/m²K
Scotland: Max 1.4 W/m²K
Northern Ireland: Max 1.6 W/m²K
Provide background ventilation with trickle vents (Approved Document F).
Meet means of escape requirements in certain rooms – minimum clear opening area 0.33 m² with both height and width at least 450mm.
Include safety glass in critical locations (e.g., glazing below 800mm from the floor).
Conservation Areas and Listed Buildings
n conservation areas or listed properties, planning permission may also apply in addition to Building Regulations.
Like-for-like replacements usually do not need planning consent.
Changes to size, style, or materials may require approval.
Listed Buildings and properties under an Article 4 Direction require listed building consent.
For detailed guidance, see our Planning Permission Guide and Conservation Areas Guide.
Certification and Proof of Compliance
When selling a property, solicitors will request evidence that any replacement windows or doors installed after June 2022 comply with current Building Regulations.
There are two ways to demonstrate compliance:
FENSA or CERTASS Certification
If your installer is registered, they will self-certify the work and issue a Building Regulations Compliance Certificate.
The certificate is also recorded with your local authority.
- If you choose Sash Window Shop for installation, our fitting partners are CERTASS-registered and fully compliant with all current Building Regulations. You’ll receive your official certificate automatically after installation — no need to apply separately.
Local Authority Building Control (LABC)
If your installer is not FENSA registered, you must contact your council’s Building Control team to inspect and certify the work.
You’ll receive a completion certificate once the installation passes inspection.
For Example
When replacing windows or doors, your new installation must not reduce the property’s existing level of safety, performance, or energy efficiency.
- You cannot remove fire escape windows and replace them with non-compliant openings.
- You cannot downgrade energy efficiency, such as fitting single glazing where double glazing existed.
- All new products should meet or exceed current standards under the relevant Approved Documents.
Key Approved Documents for Windows and Doors
Depending on the type of installation, one or more of the following Approved Documents will apply:
Part A – Structural safety
Part B – Fire safety and escape routes
Part C – Moisture resistance and site preparation
Part F – Ventilation
Part J – Combustion appliances and fuel storage
Part K – Protection from falling, collision, and impact
Part L – Conservation of fuel and power (energy efficiency)
Part M – Access to and use of buildings
Part Q – Security (for new dwellings only)
Replacing Existing Windows or Doors
If you’re upgrading existing units, the new installation must not reduce the property’s current performance.
For example:
Fire escape windows must not be replaced with non-compliant openings.
Energy efficiency ratings must be equal to or better than before.
Ventilation routes must be maintained or improved.
All products supplied and installed by Sash Window Shop are designed to meet or exceed these requirements.
New Openings and Extensions
If windows or doors are installed in a new opening, for example as part of an extension, the work must be approved by your local Building Control department or an Approved Inspector.
Our team can liaise with your contractor or architect to ensure correct specification, glazing, and frame details are used to achieve compliance.
Why Choose Sash Window Shop
Expertise in heritage and conservation properties — we work closely with planning authorities across London and the Home Counties.
Fully compliant timber products — designed to meet or exceed Building Regulation standards.
Energy-efficient glazing — including double and vacuum glazing with U-values as low as 0.4 W/m²K.
Installation support — whether supply-only or full installation, we’ll help you meet certification requirements.
For advice on compliance or documentation, contact our team.
Get in touch for a detailed quotation, or call us on 01279 456670 to discuss your project.
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