How to Install Tile Trim Around Internal and External Corners: Step-by-Step Guide

Tile trims are essential for creating clean, professional finishes — especially at corners where tiles meet. Whether you’re a DIYer or a professional installer, knowing how to finish internal and external corners correctly ensures durability, visual appeal, and a polished result.

In this guide, you’ll learn:

• The difference between internal and external tile trim corners
• Which trim profiles work best for each application
• Step-by-step installation instructions
• Pro tips and common mistakes to avoid

Internal vs External Corner Tile Trims

External Corner Tile Trim

• Used on outside edges such as pillars, boxed-in pipework, or shower walls.
• Commonly requires a square edge or round edge trim.
• Protects tile edges from chipping and wear.

Internal Corner Tile Trim

• Used where two tiled walls meet inward, such as behind sinks or in shower cubicles.
• Finished with internal corner profiles or silicone sealant where necessary.

Tools & Materials You’ll Need

• Tile trims (aluminium, chrome, brass, PVC)
• Tile cutter or wet saw
• Mitre box and hacksaw for angled cuts
• Spirit level
• Tile adhesive or bonding mortar
• Pencil/marker
• Safety gloves and goggles

Installing Tile Trim on External Corners

Step 1: Choose the Right Trim Profile

• Square Edge, Quadrant, or Round Edge trims work best.
• Ensure trim matches the tile thickness (e.g., 10mm or 12mm).

Step 2: Measure and Cut

• Measure the height or length of the corner accurately.
• Use a mitre box to cut the trim at a 45° angle for seamless joins.

Step 3: Apply Adhesive

• Spread tile adhesive where the trim will be installed.
• Press the trim firmly into place and check it is vertically level.

Step 4: Lay the Tiles

• Slide tiles into the trim channel while adhesive is still wet.
• Use spacers to maintain even joints.

Installing Tile Trim on Internal Corners

Step 1: Use a Suitable Internal Corner Profile (Optional)

• Some trims come with snap-in or slide-in internal corner joints.
• Alternatively, tile directly into the corner and finish with sealant.

Step 2: Trim and Align Tiles

• Cut edge tiles to fit flush into the corner.
• Leave a small gap (1–2mm) for movement or grout.

Step 3: Apply Grout or Sealant

• Use a grout float or sealant gun to fill gaps cleanly.
• In wet areas, apply waterproof silicone for extra protection.

Pro Tips for a Professional Finish

• Check tile thickness before buying trims.
• Use fine-tooth blades to cut metal trims without jagged edges.
• Clean excess adhesive immediately to avoid staining finishes like brushed brass or copper.
• Always dry-fit trims and tiles before permanently fixing them.

Recommended Trims for Corners

At National Tile Trims, we offer a variety of trims suitable for all corner installations:

• Wall Tile Edging Trims
• Straight Edge Tile Trim
• Formable Tile Trim – Flexible for Curves

Need help selecting the right corner tile trim? Contact us or browse our full range of trims.

FAQs About Tile Trim Corners

Can I use the same trim for internal and external corners?

It’s not recommended. External corners require protective edge trims, while internal corners often use joint profiles or sealant for a clean finish.

Do I need to mitre all external corners?

Mitred cuts create seamless joins on external edges, especially with metal trims. For PVC or flexible trims, straight cuts with pre-formed corner pieces may suffice.

What happens if I install trims incorrectly?

Improper installation can result in chipping, uneven edges, or visible adhesive. Always measure, dry-fit, and cut precisely for professional results.

Final Thoughts

Installing tile trims around corners is straightforward when you select the right profile, make precise cuts, and apply adhesive carefully. Properly installed trims improve durability, protect edges, and give your project a polished, professional look.

Next: Want to learn the difference between 10mm and 12mm trims? Read our comparison guide →