Is Part Q mandatory for my home extension?

Currently, no. Part Q generally applies to new build properties and dwellings created by a change of use. However, specifying PAS 24 compliant windows for extensions is highly recommended for security.

Does Part Q apply to first-floor windows?

Generally no, unless they are accessible via a flat roof or balcony.

Is Part Q the same as Secured by Design?

No. Part Q is the legal minimum (Building Regs), while Secured by Design is a higher Police standard.

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Part Q: What it means for your home extension

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Part Q: What it means for your home extension

📌 Approved Document Q: The Facts

The Rule: Part Q (Security) is mandatory for New Build Homes and Change of Use (e.g., barn conversions).
Extensions: It is NOT currently mandatory for standard home extensions, but it is highly recommended.
The Standard: To be Part Q compliant, windows and doors must pass PAS 24 security testing.

PAS 24 compliant secure windows and doors installed on a modern home extension

Building an extension or a new home is exciting, but the paperwork can be overwhelming. One regulation that often catches homeowners out is Approved Document Q (Security).

Introduced in 2015, Part Q was designed to ensure new homes are built to resist intruders. But does it apply if you are just building an extension? At KJM Group, we believe you should know exactly what you are paying for—and why “optional” security is usually the smarter choice.

1. What is Approved Document Q?
2. Does it Apply to Me? (The Rules)
3. The Specs: What makes a window “Part Q”?
4. Official Government Downloads
5. Frequently Asked Questions

1. What is Approved Document Q?

Approved Document Q is the section of the UK Building Regulations that deals with “Security in Dwellings.” It mandates that all easily accessible windows and doors (ground floor, or accessible via a flat roof) must be robust enough to resist physical attack by a burglar.

⚠️ The Golden Standard: PAS 24

To comply with Part Q, your windows and doors must be tested to PAS 24. This involves independent labs attacking the window with crowbars, cutting tools, and impact rams. If it survives for a set time, it passes.

2. Does it Apply to Me?

This is the most common question we get at KJM. The rules differ depending on whether you are building new or replacing old.

Do I Need Part Q?

New Build Home

Requirement

MANDATORY

Scope

All accessible windows and doors must comply.

Conversion (e.g. Barn)

Requirement

MANDATORY

Scope

Any “Change of Use” to a dwelling triggers Part Q.

Extension / Replacement

Requirement

OPTIONAL (But Recommended)

Scope

Part Q is not retrospective. However, many architects specify it for peace of mind.

💡 KJM Pro Tip: Even though it isn’t mandatory for extensions, why would you want your new room to be less secure than a new build house? We recommend specifying PAS 24 windows for all ground-floor projects to ensure your insurance is valid and your family is safe.

3. The Specs: What makes a window “Part Q”?

A standard double-glazed window might look the same as a Part Q compliant one, but physically, they are very different. To achieve the PAS 24 standard required by Part Q, the unit usually needs:

P1A Laminated Glass: At least one pane of glass must be laminated (like a car windscreen). If a burglar smashes it, it holds together rather than shattering.
Security Clips: The glass must be bonded or clipped to the frame so it cannot be removed from the outside.
Key Locking Handles: All accessible openings must be lockable.
Meeting Rails: On french doors or windows, the central meeting point must be reinforced to prevent jemmying.

4. Official Government Downloads

For the full technical details, you can download the official government Approved Documents here.

📄 The Merged Approved Documents (Oct 2024)

This is the definitive government guide containing Part Q (Security) alongside other recent updates.

📥 Download PDF (Gov.uk)

📚 Related Security Guides

Checklist: The Ultimate Home Security Checklist
Hardware: The 5 Best Security Features for New Doors
Standards: PAS 24 & Secured by Design Explained

5. Frequently Asked Questions

Currently, no. Part Q generally applies to new build properties and dwellings created by a change of use (like a barn conversion). However, many architects and homeowners choose to specify PAS 24 compliant windows for extensions anyway for peace of mind and enhanced security.

Generally, no, unless they are “easily accessible.” This means if a burglar can climb onto a flat roof or balcony to reach the window, it MUST be Part Q compliant. If it is a standard vertical wall drop, it is exempt.

Not quite. Part Q is the minimum legal requirement (building regs). Secured by Design (SBD) is a Police initiative that often demands even higher standards. However, most SBD products are automatically Part Q compliant.

Yes. If KJM installs windows that are required to be Part Q compliant (e.g. for a new build or conversion), we provide the necessary paperwork to prove the products meet PAS 24 standards. You pass this to your Building Control Officer to get your completion certificate.

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Mark Pearce

With over four decades in the glazing industry, Mark Pearce has been at the heart of KJM Windows & Conservatories since 1983. Starting as a building labourer, he quickly rose through the ranks, working as a window and door installer from 1984, a factory operator manufacturing windows later that year, factory manager in 1992, and joining the sales team in 1994. Becoming a Director in 2002, and finally, the sole owner in 2010, Mark Pearce is truly a double glazing expert and has led KJM to become a leading supplier of high-quality windows, doors, and conservatories across Andover and the South of England.

Mark Pearce is a highly experienced specialist in the double glazing industry, having built his knowledge from the ground up through hands-on experience in installation, manufacturing, sales, and business management. Beyond his role at KJM, Mark is a keen blogger, writer, and traveller, often sharing insights on the latest innovations in the home improvement industry.

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Timber - PVC - Aluminium - Windows, Doors & Conservatories in Hampshire

Part Q: What it means for your home extension