Tile trim or a mitred edge — which should I use on an external corner?
What each option demands in tools and accuracy, where each looks right, and the third option people forget.
- Difficulty
- intermediate
- Time
- 20 min
- Read
- 4 min
Short answer
A mitre looks best and needs a wet saw with a tilting head plus a steady hand — and porcelain mitres chip easily. A trim is far more forgiving and looks deliberate if it is bedded in properly and mitred at its own corners. Choose the trim unless you have the tools and the tile to mitre well.
Every tiled external corner — a window reveal, a boxed-in pipe, the end of a splashback, a shower upstand — needs an answer for the raw tile edge. The decision is usually made in the shop and it should be made against the tools you own and the tile you have bought.
Step by step
- Look at the tile edge you actually have.Some tiles have a glazed, finished edge on one or more sides and need nothing at all. Rectified porcelain has a sharp square unglazed edge that looks raw and is sharp to touch.
- Consider a mitre if you have a wet saw with a tilting table.Both tiles cut at 45 degrees so the glazed faces meet at the arris. It is the cleanest look and it keeps the tile reading as continuous around the corner.
- Be realistic about mitring porcelain.A 45 degree cut leaves a feather edge of unsupported body that chips at the slightest knock, both during fitting and in use. Leaving a small flat at the tip rather than cutting to a true point helps considerably.
- Consider a trim for everything else.Aluminium, stainless, brass and plastic profiles in various shapes. Bedded under the tile edge, it protects the corner, covers the raw edge and gives a defined line.
- Match the trim to the tile thickness.Trims are sized by the tile depth they accept. Too small and the tile stands proud of the trim; too large and there is a step and a dirt trap.
- Bed the trim as you tile, not afterwards.The trim's perforated leg goes into the adhesive under the tiles on one face, and the tiles on the return face butt against its nose. A trim stuck on at the end looks stuck on.
- Mitre the trim at its own corners.Where two trims meet — the corners of a window reveal, for example — cut them at 45 degrees. Butted trims leave a visible gap and a sharp end.
- Remember the third option: a bullnose or edge tile.Some ranges include a tile with one rounded, glazed edge. Where it exists it is the neatest solution of all, with no trim and no mitre.
Tips
- A cheap plastic trim in a prominent position is the one thing that will date the job. If the corner is on show, spend a little more on the profile.
- Brushed stainless and anodised aluminium hide scuffs far better than bright chrome, which shows every mark.
- A quadrant trim is easier to keep clean than a square-edged one, and much kinder to shins in a doorway.
- Test-fit the trim and a tile dry before committing — the relationship between trim, adhesive bed and tile face is easy to get wrong by a millimetre.
Common mistakes
- Sticking a trim onto the tiles after they have set — It sits proud, it has no mechanical support, and the joint between it and the tile becomes a dirt trap that eventually lets go. The trim is designed to be bedded under the tile edge as part of the fixing.
- Butting trims at a corner instead of mitring them — One trim's raw cut end sits against the other's face, leaving a visible slot and a sharp edge exactly where fingers go. Two 45 degree cuts take a minute.
- Mitring porcelain to a true knife point — The tip is unsupported body with no glaze on it. It chips when you press the tile into the adhesive, and again the first time anything touches the corner.
Questions people ask
Is a mitre always better looking?
A good mitre, yes — the tile appears to fold round the corner. A poor mitre, with a chipped tip or an inconsistent joint, looks far worse than a well-fitted trim. The realistic comparison is a good trim against the mitre you can actually cut.
Can I mitre with an angle grinder?
It can be done, freehand, with a diamond blade, and it is very hard to keep straight. It also produces a great deal of silica dust — so if you do it, it is a wet-cut or on-tool-extraction job with an FFP3 mask, outdoors, not a quick dry cut in the bathroom.
What about the internal corners?
Internal corners need neither: the tiles simply butt into the corner. But the joint there is a movement joint, so it gets flexible sealant rather than grout.