2mm Aluminium Flat Coping – 90° T-Junction | 75mm External Leg

Where a parapet wall joins another wall at a right angle from one side only, creating a T-shaped intersection, the coping needs to transition cleanly from two runs into three. A standard 90 degree corner only handles a change of direction. A T-junction handles a change of direction plus an additional wall coming in from the side. Without a properly formed T-junction piece, you are left trying to cut and join three coping sections on site, which creates multiple exposed joints, inconsistent angles, and a weak point where water will find its way through.

A factory formed aluminium coping T-junction provides a single, pre-formed piece that connects all three coping runs at the intersection. It is powder coated to match the coping lengths, uses the same concealed fix bracket system, and maintains a weathertight seal across the entire junction. On parapet walls across Chelmsford, Brentwood, Colchester and the wider South East, this is the fitting that keeps the coping system continuous at every T-shaped wall intersection.

Product Overview

The 2mm aluminium flat coping T-junction from Online Metal Store Ltd connects three coping runs at a T-shaped parapet wall intersection. The 75mm external leg (downstand) matches the standard leg dimension on the flat coping 3m lengths and flat coping 1m lengths, keeping the profile consistent across the entire coping system. Available in multiple width options to match your wall thickness, custom fabricated at our Chelmsford, Essex workshop and powder coated in any RAL colour.

The T-junction is supplied with fixing brackets for the concealed fix installation. For standard changes of direction (where the wall turns 90 degrees), see the 90° coping corner. For the end of a coping run, see the coping stopend range. Browse the full aluminium copings collection for all lengths, corners, T-junctions and stopends.

Key Benefits

Connects Three Coping Runs at One Point

The T-junction is factory formed to connect the main coping run with a branch wall coming in from one side. This creates a clean, weathertight transition at the intersection without multiple site-cut joints. A 90 degree corner only handles two runs. The T-junction handles three.

75mm External Leg for Consistent Profile

The 75mm downstand matches the standard leg dimension across the flat coping range, including the 3m and 1m coping lengths. This keeps the coping line consistent at every fitting.

Concealed Fix Bracket System

The T-junction is supplied with fixing brackets that secure to the top of the wall. The coping clicks down onto the brackets with no visible screws or fixings on the finished surface. This maintains a clean architectural line at the junction.

Powder Coated in Any RAL Colour

Every T-junction is colour matched before dispatch, using the same RAL code as the coping lengths and corners for a consistent finish.

UK Manufactured with Fast Turnaround

Fabricated at our workshop in Chelmsford, Essex alongside the coping lengths and other fittings.

Technical Specifications

Material: 2mm aluminium

Type: Flat coping T-junction (tee piece)

External Leg: 75mm downstand with 10mm return

Available Widths: Multiple options to match wall thickness (select at checkout)

Finish: Polyester powder coated in any RAL colour

Fixing: Concealed bracket system (brackets supplied)

Fire Classification: A2-s1,d0 under BS EN 13501-1

Manufactured: Chelmsford, Essex, United Kingdom

How to Fit an Aluminium Coping T-Junction

Fix the supplied brackets to the top of the wall at the T-junction intersection using appropriate fixings into 18mm external grade plywood or directly into the masonry. Apply EPDM seal tape to the brackets. Click the T-junction piece down onto the brackets, ensuring it seats firmly and aligns with the coping runs on all three sides.

Leave a 2 to 3mm expansion gap between the T-junction and each adjoining coping length. The gaps allow for thermal movement while the EPDM tape maintains the weathertight seal. Ensure the waterproof membrane underneath is correctly detailed before fitting the coping. For a completed installation reference, see the how to install aluminium coping guide.

Where Coping T-Junctions Are Used

Parapet Wall Intersections

The most common use is where a parapet wall on one section of roof meets a perpendicular parapet wall from an adjacent section, creating a T-shape when viewed from above. This occurs on flat roofed buildings with multiple bays, wings or roof levels across Chelmsford, Brentwood, Basildon and the South East.

Extension Junctions

Where a flat roofed extension meets the main building parapet, the coping often needs to transition from the extension wall into the main wall, creating a T-junction at the meeting point.

Commercial Rooflines

On commercial buildings, retail units and office blocks with complex parapet geometries, T-junctions occur wherever a dividing wall or fire break wall meets the perimeter parapet.

Frequently Asked Questions

What is a coping T-junction used for?

A coping T-junction connects three coping runs at a T-shaped wall intersection. It is used where one parapet wall meets another at a right angle from one side only, creating a T-shape when viewed from above. A standard 90 degree corner only handles two runs. The T-junction handles three.

When do I need a T-junction instead of a corner?

Use a T-junction where a wall joins another wall from one side only (T-shape). Use a 90° corner where the wall changes direction (L-shape). If you stand above and the walls form a T, it is a T-junction. If they form an L, it is a corner.

What size coping T-junction do I need?

The coping width must match your wall thickness plus the 75mm downstand and 10mm return on each side. Measure the wall thickness and select the matching width option. The 75mm external leg is standard across the flat coping range.

How do you fit an aluminium coping T-junction?

Fix the supplied brackets to the wall top. Apply EPDM seal tape. Click the T-junction down onto the brackets. Leave a 2 to 3mm expansion gap between the T-junction and each adjoining coping length.

Can the coping T-junction be colour matched?

Yes. Powder coated in any RAL colour. Order in the same RAL code as your coping lengths and corners for a fully matched system.

Part of a Complete Flat Coping System

The T-junction is one fitting in the flat coping system:

• Flat Coping 3m Length – main coping length

• Flat Coping 1m Length – short coping length

• Coping T-Junction – this product

• Coping Bracket – concealed fixing bracket

Browse the full aluminium copings collection for all lengths, corners, T-junctions and stopends. The coping system works alongside aluminium fascia and soffits, drip trims and the full rainwater goods range. For a completed project, see the Mellish Street coping case study.

Standards and Compliance

The powder coat finish is applied in line with BS EN 12206-1 for powder organic coatings on aluminium. The coping system achieves a fire classification of A2-s1,d0 under BS EN 13501-1, making it non-combustible and suitable for buildings of any height.