Mirrors near you

Approved Document K's requirement K4 covers protection against impact with glazing in critical locations, and the locations it identifies are areas of glazing in internal and external walls and in doors — the transparent elements at low level in a door, beside a door, or in a wall, which someone might fall against or walk through. A mirror fixed to the face of a solid wall is not one of those. There is a wall behind it. Nobody is going to walk through it or fall out of the building through it.

The other provision people reach for is manifestation, and it does not apply either. Approved Document K's requirement K5.2 is met by including, in critical locations, permanent means of indicating the presence of large uninterrupted areas of transparent glazing — but section 7 defines those critical locations as large uninterrupted areas of transparent glazing forming or part of the internal or external walls and doors of shops, showrooms, offices, factories, public or other non-domestic buildings. A domestic hallway is not on that list, and a mirror is not transparent in any case.

That absence of regulation is worth stating plainly rather than implying a standard that does not exist. It means a large mirror in a British home is governed by the contract you make with the installer and by ordinary product safety law, not by building control. It also means that if a supplier tells you a domestic mirror must be a particular specification to comply with the Building Regulations, they are describing something that is not there — which is not a reason to under-specify, but is a reason to understand why you are specifying it.

The single most useful thing you can buy on a large mirror is a safety backing: a film or coating bonded to the rear face so that if the glass breaks, the pieces are held together rather than falling as blades. It costs very little on top of the glass, it is invisible in use, and it changes the failure from a serious injury into an inconvenience. For anything above about waist height, anything in a bathroom, anything in a hallway and anything in a child's room, it should be the default rather than the upgrade.

For the classification itself, the relevant British code of practice is BS 6262-4, Glazing for buildings — Code of practice for safety related to human impact, currently the 2018 edition. It gives safety recommendations for the use of glass and plastics glazing sheet materials in locations likely to be subject to accidental human impact, covering the vertical use of those materials in order to reduce impact-related injuries and particularly the risk of cutting and piercing injuries. Naming it in a specification gives you a shared reference point with the installer.

Beyond the backing, three material choices matter. Silvered float glass is the standard product and is fine in a dry room. A copper-free, moisture-resistant mirror is a better choice in a bathroom, because the classic black creep at the edges of an old bathroom mirror is corrosion of the reflective layer. And polished or bevelled edges are not only cosmetic: a raw cut edge is where damage starts, and a sealed, polished edge is more durable in a damp room.

British internal walls are not all the same thing, and the fixing that works in one will fail in another. Solid masonry takes a plugged and screwed fixing well. A timber stud wall will hold almost anything if you hit the studs and very little if you do not. And dot-and-dab plasterboard — boards stuck to masonry on blobs of adhesive, extremely common in houses and flats built or refurbished since the 1980s — leaves a void of an inch or so behind the board, so a plasterboard fixing is anchored in a sheet that is itself only glued on.

That void is where heavy mirrors come off walls. The right approach on dot-and-dab is to fix through the board into the masonry behind, with a plug long enough to bridge the cavity and reach solid material, rather than relying on a hollow-wall anchor. Finding out which construction you have takes a moment with a small drill and a tape, and it is a question worth asking any installer before they start — the answer should not be a guess.

Adhesive fixing deserves particular care, because it is popular and permanent. Only a mirror-safe adhesive should touch the back of a mirror: ordinary solvent-based products attack the reflective coating and produce dark blotches that appear months later. Adhesive alone is also not a support on a large panel — mechanical support at the bottom edge while the adhesive cures, and ideally permanently, is what keeps a heavy sheet where it was put. And a mirror bonded to tile is only as secure as the tile's bond to the wall.