Buy a new-build home in England and the sales brochure may mention “Secured by Design” or simply that the property “meets Building Regulations.” These are not the same thing, and only one of them is a legal minimum every new dwelling must meet. That minimum is set out in Approved Document Q, and most homeowners have never read it, even though it determines exactly how resistant their front door and ground-floor windows are supposed to be to a casual break-in attempt.
What Approved Document Q actually covers
Approved Document Q supports Requirement Q1 of Schedule 1 to the Building Regulations 2010, which requires that “reasonable provision must be made to resist unauthorised access” to a dwelling. According to the guidance published on the Planning Portal, it applies to doors and windows that are “easily accessible” — broadly, ground-floor openings and any upper-floor opening reachable from a flat roof, balcony or similar structure — in newly built dwellings. It took effect on 1 October 2015 for use in England, and it also applies to building work on excepted energy buildings in Wales, but it does not extend to Scotland or Northern Ireland, which regulate new-build security through their own separate frameworks.
Crucially, Document Q is a new-build control. It is triggered by the Building Regulations application for a new dwelling, not by someone replacing a door or window in an existing home. If you are re-fitting your own front door, Document Q itself does not compel you to use a tested product — though your insurer or a separate FENSA/CERTASS competent-person scheme may still expect one.
PAS 24: the test standard behind the requirement
To demonstrate compliance, doors and windows in scope are expected to meet PAS 24, the Published Assessment Specification for enhanced security performance of doorsets and windows. PAS 24 is not a test of an individual lock or handle in isolation; it is a whole-assembly performance test covering the frame, glazing, seals, hinges, locking hardware and the way they work together, subjected to standardised manual and mechanical attack methods for a defined period. A doorset that passes has demonstrated it can resist the tools and techniques typically used by an opportunistic burglar for long enough to make the attempt not worth continuing, not that it is unbreakable.
How this differs from Secured by Design and BS3621
Secured by Design, the official police-backed crime prevention initiative, is a voluntary specification that developers can choose to build to. It generally goes further than the Document Q minimum, because it looks at a whole development — layout, boundary treatment, lighting and communal areas — rather than just the doors and windows of an individual dwelling, and it uses PAS 24 compliance as one component of a wider accreditation rather than as the entire requirement. Not every new-build meets Secured by Design; every new-build in England is, in principle, required to meet Document Q.
BS3621, by contrast, is a lock standard used mainly in the existing-homes insurance market, specifying five-lever mortice locks with a minimum number of key differs and resistance to drilling and picking. It sits alongside Document Q rather than replacing it: a new-build doorset can be PAS 24 tested as a complete assembly without using a BS3621 mortice lock at all, since many PAS 24 doorsets use multipoint locking systems with rated cylinders instead.
What this means if you are buying or renovating
If you are buying a new-build home, the building control completion certificate and the developer’s specification should confirm that ground-floor and easily accessible doors and windows meet Document Q via PAS 24. It is a reasonable question to put to a sales team directly, and reputable developers should be able to point to the relevant test certificates for the doorset and window systems used, rather than a general reference to “toughened glass” or “multipoint locking,” neither of which is a substitute for the PAS 24 test itself.
If you are renovating or extending an existing home, be aware that a material change of use, a loft conversion creating new independent access, or certain large extensions can bring Document Q into scope for the new work even though the original dwelling was never covered by it. This is worth raising with your building control body or approved inspector at the design stage rather than after windows have already been ordered, since retrofitting a compliant doorset is considerably more disruptive than specifying one correctly the first time.
Finally, Document Q sets a floor, not a ceiling. It does not cover back doors or windows that are not “easily accessible,” it says nothing about intruder alarms, and it does not evaluate the wider layout of a street or estate the way Secured by Design does. A new-build home that meets Document Q has a legally required baseline of resistance on its most vulnerable openings; anything beyond that, from alarm systems to additional door furniture, remains a choice for the homeowner.