Because nothing else is holding it up. In a framed unit the profile resists bending and spreads load along the whole edge; remove it and the pane itself has to do both.

Load also concentrates dramatically at the fixings. A hinge or clamp drives the whole mass of the door through a small area of glass, and thin glass cannot carry that without risk at the hole.

Thicker panes are heavier to handle, need stronger wall fixings, and are a large part of why a frameless enclosure costs more before anyone has fitted it.

There is no adjustment to hide behind. A framed enclosure absorbs a leaning wall in its profile; a frameless one meets the wall with a bare edge, so any discrepancy is visible as a wedge of light.

That means the walls have to be checked properly beforehand and, where they are out, packed or made good rather than accommodated by the product.

The panes are also heavy enough to need two people, and drilled holes are permanent — toughened glass cannot be cut or adjusted after it has been made.

No, and this surprises people. There are still clear seal strips at the door edges and usually a drip strip along the bottom; what has gone is the metal, not the sealing.

Those strips are consumable. They perish, discolour and eventually stop meeting the adjacent pane, and they are the most common thing to replace on a frameless enclosure.

The good news is that they are cheap and clip on, so a tired frameless unit usually needs new seals rather than new glass.

Genuinely so, and it is a practical advantage rather than only an aesthetic one. There are almost no channels to hold water, so far less residue accumulates.

What remains is the glass itself, and an easy-clean coating helps there by reducing how much limescale keys to the surface.

The caveat is that any coating is a treatment with a life, not a permanent property, and abrasive cleaners will take it off faster than time will.

Something structural. The whole weight of a heavy pane, plus the leverage of a door being pushed, arrives at a handful of fixings.

Tile over plasterboard will not hold that on its own; the anchor has to reach masonry or a properly positioned nogging behind the board, and that has to be planned while the wall is still open.

This is the single most common cause of a frameless enclosure moving in service, and it is settled at first fix rather than something correctable at the end.