PART Q · Security
Does Part Q apply to replacement windows
Ordinary replacement windows in an existing home do not automatically trigger Part Q's new-dwelling security requirement. Part Q should not be presented as a blanket retrospective rule for all existing houses. The actual project and its scope matter.
What if a conversion creates new flats
Creating new dwellings through a relevant material change of use is different from replacing windows in an established home. Part Q can be relevant to that conversion.
Ask the designer to classify the work correctly before deciding which openings need the specified security performance.
Does an exemption mean any window is acceptable
No. Other requirements may still apply, including energy performance, ventilation, safety glazing and relevant escape provisions. Security should also be considered as a practical design matter.
For example, a replacement window that improves locking but removes an intended escape function needs a wider review.
Should I choose a tested security product anyway
That can be a sensible voluntary choice. Ask what the performance evidence covers and whether it matches the unit, hardware and glazing being quoted.
Separate a supplier's useful security recommendation from a claim that the law requires every existing window to be upgraded to Part Q.
What should the installer explain
Ask for the applicable building regulations route, the ventilation provision and the specification of relevant safety or escape features. Discuss how the opening will operate after replacement.
If the project is part of a larger conversion or redevelopment, tell the installer. Assessing each window job in isolation can miss the wider regulatory context.
What should you keep
Retain installation and compliance records, along with any security evidence relied on. Check that the paperwork identifies the actual units provided.
The useful question is not simply whether the window carries a Part Q label. It is which requirements apply to this work and how the finished installation meets them.