Building Regulations for Windows & Doors (UK Guide 2026)

Understand the UK Building Regulations for Windows and Doors used in the refurbishment of existing and New Build properties. Learn about Parts L, F, Q, O and safety glazing requirements

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What Are Building Regulations?

Building regulations are legal standards that ensure buildings are safe, energy efficient, and suitable for occupation. For windows & doors, they cover areas such as energy efficiency, ventilation, safety glazing, fire escape, accessibility and overheating

Part L Energy Efficiency

Sets the minimum thermal performance for windows & doors to reduce heat loss

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Part F Ventilation

Explains when background ventilation is required for habitable rooms

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Part Q Security

Requires new dwellings to meet security standards such as PAS24 for windows & doors

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Part O Overheating

Helps reduce the risk of over heating in homes with large glazed areas

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Part K Safety Glazing

Safety glass is required in certain critical locations where impact is likely

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Part B Fire Safety

Covers escape windows, fire rated glass and means of escape in buildings.

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Do Replacement Windows Need Building Control?

In most domestic properties, replacement windows must comply with Building Regulations. This is usually demonstrated by installation through a Competent Person Scheme (such as FENSA, CERTASS or ASSURE) or by inspection and approval from Local Authority Building Control.

Building Regulations Checklist.

  1. Do the windows meet the required U Value?
  2. Are Trickle Vents required?
  3. Is safety glazing needed?
  4. Does Part Q apply?
  5. Is an escape window required?
  6. Will Building Control need to inspect the work?

Frequently Asked Questions

PAS24 is not a legal requirement for every window or door installation. However, it is commonly required on new-build dwellings where Building Regulations Part Q applies. PAS24 is a recognised security standard that demonstrates a product has been independently tested against forced entry. If you’re unsure whether your project requires PAS24-compliant products, our team can advise you.

Not always. Whether trickle vents are required depends on the property’s ventilation strategy and the requirements of Building Regulations Part F. In many replacement window installations, background ventilation is required, but there are exceptions where alternative ventilation methods are already in place. A professional survey will determine the correct solution for your property.

The easiest way is to choose an installer who is registered with a Competent Person Scheme, such as Assure, FENSA or CERTASS. They will ensure your new windows and doors comply with the latest Building Regulations and will provide the appropriate certification once the installation is complete. If Building Control approval is required, they can also guide you through that process.

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Our team can help you choose the right windows and doors that comply with all relevant Building Regulations.

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