Summary

Tile trim is the strip of metal, PVC or composite that finishes the exposed edge of a tiled area. Done well, it is invisible — the eye reads a clean line where tile meets paint and moves on. Done badly, it is the single thing that gives away an amateur tile job: clear caulk smears, the wrong colour against the tile, trim that's the wrong depth, mitres that don't line up, ends that aren't capped.

For a tradesperson, trim choice is one of the most undervalued estimating items. Customers don't ask about it during the quote; they notice it the moment the job is finished. The difference between a £4 PVC strip and a £25 brushed-brass piece per metre is significant on a full bathroom, and steering the customer to the right finish — at the right margin — is part of the job.

This article covers profile types, sizing rules, materials and finishes, installation method, mitring inside and outside corners, and common faults. Decorative trims (Schlüter-Dilex, JOLLY, RONDEC, QUADEC and their generic equivalents) are covered alongside basic right-angle and round-edge profiles.

Key Facts

Quick Reference Table

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Trim depth Suits tile thickness Typical use
6mm 6mm wall tile Splashback, kitchen wall, light-use bathroom
8mm 8mm wall tile Standard ceramic bathroom wall
10mm 10mm porcelain wall, 10mm floor Standard porcelain bathroom/kitchen
11mm 10mm tile + thicker bed Heavy porcelain wall or feature floor
12.5mm 12mm floor tile Standard kitchen floor porcelain
15mm 12–14mm tile + thick bed Large-format floor, terrace
20mm+ Outdoor 20mm porcelain Patio paving, terrace
Profile Edge shape Best for
RONDEC Rounded over Soft contemporary, family bathrooms, no sharp edge
JOLLY Squared / 90° angle Modern square-edge contemporary, sharper lines
QUADEC Square-stepped Trim is the same depth as the tile face — most flush look
DILEX Movement / corner Internal corners and movement joints in floor runs
Pencil-round Soft pencil shape Traditional, more classical
External corner Two-side L-piece Outside corners without mitring

Detailed Guidance

Choosing the right profile

The profile dictates the visual style of the tile edge. RONDEC is the safest choice for any room and the default for accessible/safety-conscious installs because it eliminates sharp edges entirely. JOLLY is the modern default in contemporary schemes — it sits 90° to the wall with a sharp clean line. QUADEC is the most "invisible" option because the trim face is exactly the tile depth — looks like a continuation of the tile edge.

Avoid mixing profiles within one room. Pick one profile, one finish, one depth, and use it everywhere.

Sizing — get this wrong and you'll redo the job

The trim depth is the GROUND clearance from the substrate (wall/floor) to the FACE of the tile, INCLUDING the adhesive bed. A 10mm porcelain on a 3mm notch trowel bed = ~12–13mm total — use a 12.5mm trim. Too shallow and the trim sits below the tile face (looks recessed, collects water in showers). Too deep and the trim stands proud (looks like a step, snags towels, chips easily).

Always measure your actual fixed-tile depth on a sample board before ordering trim in bulk. Different batches and different adhesives change the dimension.

Installation procedure

  1. Measure the run, deducting trim depth from the tile field where the trim sits.
  2. Cut trim to length with a fine-tooth hacksaw or mitre saw with a non-ferrous blade.
  3. Mitre internal/external corners (45° each piece) — measure twice; the visible line is unforgiving.
  4. Apply adhesive to the wall/floor as normal.
  5. Press the perforated flange of the trim into the wet adhesive, with the trim face flush to where the tile face will sit.
  6. Lay the adjacent tile, bedding it tight against the trim flange.
  7. Wipe excess adhesive immediately — dried adhesive on aluminium is hard to remove without scratching.
  8. Grout the joint between trim and tile (some grout colours bleed onto matt aluminium — test first).
  9. Caulk where the trim meets paint/plaster on the open side.

Mitred corners

For external corners, two pieces of trim cut at 45° give a hairline mitre line. This is the highest-skill part of trim work. Use a fine non-ferrous mitre blade and a mitre stop. Test-fit dry before bedding. If the wall isn't perfectly square (most aren't), the mitre will gape — pre-check with a square and adjust the angle slightly to compensate.

A pre-formed external corner piece is the alternative — easier but adds a visible vertical line at the corner. Many professionals prefer the corner piece in budget jobs and the mitre in premium jobs.

Internal corners and movement joints

Internal corners should NEVER be grouted. Two tile runs meeting at an internal corner will move differentially due to thermal expansion, building settlement, or substrate movement. Grout in this joint will crack within months. Use either:

Where trim is NOT needed

Frequently Asked Questions

Can I retro-fit trim to an existing tile job?

Sometimes. If the tile edge has been left exposed, you can sometimes glue a flat-back PVC or aluminium "corner protector" trim over the existing edge with grab adhesive. It will look like a retrofit because the trim sits on top of the tile face, not bedded behind it. The result is acceptable on a small repair but not a finished-quality look.

Do I need movement trim on a small bathroom?

A typical 6m² domestic bathroom doesn't usually need a dedicated DILEX movement joint — silicone in the internal corners and at the floor/wall junction is sufficient. Movement joints become required on runs over 8m, on heated floors (UFH), and on any commercial install per BS 5385-3.

What's the cheapest trim that doesn't look cheap?

White PVC RONDEC is the budget default in starter rentals — invisible if the wall is white and the tile is matt white. Aluminium chrome RONDEC at £4–8 per 2.5m length is the next step up and looks materially better than PVC for a small price difference. Avoid coloured PVC trims (turn yellow under sunlight, crack under thermal cycling).

How do I cut aluminium trim without damaging the finish?

Use a fine-tooth hacksaw (32 TPI) or a non-ferrous mitre blade. Tape the trim with low-tack masking tape over the cut line — reduces burr and stops the saw skidding. File the cut edge with a fine flat file. Anodised finishes show scratches on raw cut edges — colour-match with a touch-up pen for premium jobs.

Regulations & Standards