Choose the framing level from what the walls can be made to do rather than from how the enclosure should look. A frameless enclosure puts the glass edges on show and relies on walls that are flat, plumb and finished; a framed enclosure covers the junction between glass and wall, so it can work where the wall is sound but not perfect. The wall decides the frame, not the other way round.
The reverse order is what produces rework. A frame is bought because it looks right, the walls are found to be out of line at the fixing height, and the frame turns out to be covering a gap the enclosure cannot close. Reading the wall first removes that risk at the only point where it is cheap to remove.
Where Framing Absorbs Error
Framing absorbs error at specific places, and knowing where they are explains what any given enclosure can and cannot forgive.
- At the junction between glass and wall. A frame or a channel covers the edge of the glass where it meets the wall, so a wall that is slightly out of line produces a junction that still looks straight.
- At the head and the base. A top rail or a bottom track closes the enclosure at the top and the bottom, and in doing so takes up small differences in level along those lines.
- At the fixing points. Brackets and plates allow a small amount of movement at the fixing itself, which absorbs minor variation in the wall behind them.
- Between the panels. A frame separates the glass elements, so differences between them are carried by the frame rather than by the glass edges aligning.
What framing does not do is change the shape of the wall. It covers junctions, it carries small differences and it moves the visible line from the glass edge to the frame - all of which are useful, and none of which is tolerance in the engineering sense.
Reading Wall Condition
Four readings decide which framing level a wall can take, and all of them are taken at the height the enclosure will use rather than at eye level or at the floor.
| What to read | How it is read | What it decides |
|---|---|---|
| Plumb at the fixing height | A level held against the wall where the hinge, track or channel lands | Whether a glass edge can sit parallel to the wall |
| Flatness across the fixing line | A straight edge held against the surface along the line the enclosure follows | Whether a frame or channel can seat without packing |
| What the wall is made of | The substrate behind the finish, identified rather than assumed | What the fixing can hold, and how the door is anchored |
| Whether the surface is final | Confirmation that tiling or finishing is complete | Whether the measurement is the one the door will be made to |
Two readings are more often skipped than the others. Flatness is one: a wall can be plumb at both ends of a run and still bow in the middle, and the straight edge is the only tool that shows it. The state of the finish is the other: a measurement taken through a temporary surface is a measurement of a wall that will not exist on the day of installation, and the shower door wall types guide explains how tiling, drywall and fibreglass differ as both a surface and a fixing base.
Tolerance by Framing Level
The three levels of framing differ in how much of the wall they cover, and therefore in how good the wall has to be.
| Framing level | What it can work with | What it still requires |
|---|---|---|
| Frameless | Walls that are flat, plumb and finished at the fixing line | Glass edges that sit against the wall without packing or visible gaps |
| Semi-frameless | A wall that is sound and reasonably true, with a frame on part of the enclosure | The junction the frame covers has to be the one that is least true |
| Framed | A wall that is workable rather than perfect, since the frame covers the perimeter | A substrate the fixings can hold, and a surface that is final |
The comparison is not a quality ranking. A frameless enclosure on walls that suit it is the simplest arrangement to keep clean; the same enclosure on walls that do not suit it produces a poor result and a difficult installation. The frameless versus semi-frameless guide covers the comparison in detail.
Limits of Framing Tolerance
Each level covers a junction, and each level stops at the same place: the fixing line and the substrate behind it.
- A wall out of plumb at the fixing height cannot be corrected by a frame, because the frame follows the wall it is fixed to.
- A bowed wall leaves a glass edge or a channel sitting proud in the middle of its run, which framing cannot hide.
- An opening that has already moved - a base that was reset, a wall that has settled - moves whatever is fixed to it afterwards, whatever the framing level.
- A wall that cannot hold the fixing is a limit for every level, including the most heavily framed one.
Where a wall is out of line in a way that framing cannot absorb, the useful options are to correct the wall, to change the arrangement so the enclosure fixes to surfaces that are true, or to accept a smaller enclosure built to the opening as it is - which is the route the uneven wall guide describes.
Framing decides how much of the wall is covered, not how much error the wall is allowed to carry: once the fixing line is out of plumb, out of flat, or attached to something that cannot hold, the limit has been reached and the answer is to change the wall or the arrangement rather than the frame.
