2mm Aluminium Sloping Coping – 2m Length | 125mm External Leg - Online Metal Store Ltd

2mm Aluminium Sloping Coping – 2m Length | 125mm External Leg

£61.85
(£74.22 Inc VAT)

2mm Aluminium Sloping Coping – 2m Length | 125mm External Leg

On a new-build housing development where the house type has an insulated cavity wall parapet, two things are typically true: the parapet wall is wider than a domestic single-skin extension would produce, and the parapet faces on individual house types are often in the 3m to 5m range. Those two facts together make the 125mm external leg the right leg size, the wider wall needs a proportionally wider overhang and the 2m section the right run length for those mid-range face dimensions. A 4m parapet face on a house type with a cavity wall takes two 2m sections with one joint and no waste. A 5m face takes two 2m sections and a 1m cut, or alternatively a 3m length and a 2m section for better joint economics. The 2m length in the 125mm system serves this combination of specification and layout better than any single alternative.

This is the 2mm aluminium sloping coping in a 2m length with a 125mm external leg. It is the 125mm system companion to the 2m length in the 100mm system, carrying the same built-in slope, the same 29 available width sizes, and the same system compatibility, but with a 25mm wider external leg for walls where the wider overhang is the correct specification. Manufactured in Chelmsford, Essex, powder coated in any RAL colour, made to order and non-returnable unless faulty.

100mm or 125mm External Leg: A Quick Summary

The full 100mm vs 125mm selection guide, including the wall width proportion argument, the housebuilder specification context and the water throw-off distance rationale, is on the 125mm sloping coping 1m length page. In brief: the 100mm external leg is the standard domestic choice for single-skin parapet walls up to approximately 200-250mm wide. The 125mm leg is the correct specification for cavity wall parapets, wider residential and light commercial wall constructions, projects where the housebuilder or architectural specification calls for a minimum 125mm overhang, and any project where a more substantial drip detail and wider visual profile are required. The 125mm system uses a different sizing formula from the 100mm system, see the size calculation section below.

Why the 2m Length Works for This System

The full case for using 2m sections over 1m or 3m including the joint count arithmetic and the box dormer scenario is on the 2m 100mm sloping coping page. The same logic applies here: the 2m section halves the joint count of an equivalent 1m layout and produces less waste than a 3m section on runs between 2m and 5m long. In the 125mm system specifically, the 2m length is particularly well matched to the medium parapet faces typical of new-build housing with cavity wall construction, where individual parapet faces of 3m to 5m are common and the wider leg is specified throughout. Two 2m sections cover a 4m parapet face with one joint and zero waste a clean, efficient result for a face that is among the most visible parapet details on a domestic new-build.

Product Overview

This 2m length is part of the Online Metal Store Ltd 2mm aluminium sloping coping system with a 125mm external leg, fabricated at the Chelmsford facility. The 125mm external leg extends 25mm further beyond the wall face than the 100mm equivalent, providing a wider drip detail and a more substantial visual profile at parapet level. The 75mm internal leg returns down the inside face of the parapet. The slope tilts toward the external face so rainwater drains actively off the coping and over the 125mm drip edge. The 29 available width sizes from 185mm to 885mm cover parapet wall widths appropriate for the 125mm leg specification. The 4mm aluminium coping bracket is the correct concealed fixing bracket for this 2mm system.

This 2m section is fully compatible with every accessory in the 2mm sloping coping 125mm system: the 1m length and 3m length in the same profile, all four corner types, left and right handed stopends, stopend upstands, and the 4mm bracket. Accessories for the 125mm system are different products from the 100mm system accessories: they have different profile dimensions and are not interchangeable. Order all accessories in the 125mm leg size to match.

Key Benefits

125mm Overhang for Cavity Wall and Wider Parapet Constructions

The wider external leg provides more positive clearance between the drip point and the wall face below. On a cavity wall parapet with a rendered or painted external wall finish, the 25mm extra clearance over the 100mm system keeps the discharge point further from the surface, reducing long-term staining, efflorescence and surface degradation beneath the drip line. On new-build housing development sites across Essex and the Home Counties, the 125mm external leg is the standard specification for this reason: it protects the wall face finish over the lifetime of the building more effectively than the narrower alternative.

2m Length for Fewer Joints on Medium Faces

Two 2m sections cover a 4m parapet face with one joint. Four 1m sections cover the same face with three joints. Each joint is a sealant line and a maintenance dependency; reducing joint count on a visible parapet face is a quality improvement with no additional material cost when the 2m length fits the run. On a new-build housing development where the same house type is repeated across multiple plots, reducing joint count per plot reduces the total sealant application requirement across the development and improves the consistency of the finished installation.

Built-In Slope for Active Surface Drainage

The sloped profile tilts toward the external face across the full 125mm overhang, directing surface water off the coping and well clear of the wall below. The wider the external leg, the further out the drip point sits, and the more effective the drainage clearance. On a south-west-facing parapet on a new-build house in the South East, this combination of wider overhang and active slope provides efficient rainwater management across all weather conditions without any maintenance intervention.

Powder Coated in Any RAL Colour

The finish on every component in the 2mm sloping coping 125mm range is an external grade polyester powder coat available in any RAL colour. For a new-build development where the coping colour is part of the house type specification, ordering all components 1m sections, 2m sections, 3m sections, corners, stopends and brackets in the same RAL ensures all pieces go through the same coating batch at Chelmsford and arrive colour-matched across the full system.

UK Manufactured in Chelmsford, Made to Order

Fabricated at the Online Metal Store Ltd facility in Chelmsford to the width size and RAL colour specified at order. Non-returnable as a made-to-order custom fabrication. The 125mm sizing formula (wall width + 220mm, not + 195mm) is explained in the size calculation section below and must be applied correctly before ordering. Measuring from an installed 125mm coping section across the full profile is the most reliable confirmation.

Technical Specifications

Material: 2mm grade aluminium

Profile: Sloping coping length

Length: 2m (2000mm)

External Leg: 125mm

Internal Leg: 75mm

Width Sizes Available: 185mm, 210mm, 235mm, 260mm, 285mm, 310mm, 335mm, 360mm, 385mm, 410mm, 435mm, 460mm, 485mm, 510mm, 535mm, 560mm, 585mm, 610mm, 635mm, 660mm, 685mm, 710mm, 735mm, 760mm, 785mm, 810mm, 835mm, 860mm, 885mm (29 sizes in 25mm increments)

Size Note: The "size" refers to the overall WIDTH of the coping profile, NOT the run length. All lengths on this page are 2m long. The size determines the coping girth to match your wall width.

Sizing Formula: Wall width + 220mm = size to order (125mm external leg + 75mm internal leg + 10mm + 10mm returns = 220mm). This is 25mm more than the 100mm system formula (wall width + 195mm).

Finish: Polyester powder coating, external grade

Colour: Any RAL colour to order

Compatible Bracket: 4mm Aluminium Coping Bracket (2mm coping system)

Fabrication: Made to order non-returnable unless faulty

Country of Manufacture: United Kingdom (Chelmsford, Essex)

The 125mm Sizing Formula: Wall Width + 220mm

The 29 size options from 185mm to 885mm refer to the WIDTH of the coping profile, not the run length. Every section on this page is 2m long. The size must match the overall girth of your parapet wall, calculated as follows:

  • Measure the parapet wall width at the top from outside face to inside face.

  • Add 125mm (external leg) + 75mm (internal leg) + 10mm + 10mm (returns) = 220mm.

  • Total: wall width + 220mm = the size to order. A 165mm wide wall gives 385mm. A 240mm wall gives 460mm. A 315mm wall gives 535mm.

  • Critical note: this formula gives results 25mm larger than the 100mm system formula (wall width + 195mm). For the same parapet wall, the 125mm system size is always 25mm wider than the 100mm system size. Do not use the 100mm formula for a 125mm installation.

  • If the calculated size falls between two available sizes, select the next size up.

  • Quickest site check: measure the overall width of an installed 125mm section or bracket across the full profile. That measurement is the size.

How to Install 2mm 125mm Sloping Coping 2m Lengths

Mark bracket positions along the full parapet run before fixing. Fix the 4mm aluminium coping brackets at the correct centres maximum 1000mm with brackets within 150-200mm of every run terminal, corner junction and stopend position. For a 2m length, a minimum of three brackets is required: one near each end and at least one intermediate. Confirm all brackets are flat to the wall top and that the alignment line is true before pressing any coping into place.

Press the 2m 125mm coping sections onto the brackets from the fixed terminal end of the run. Apply a continuous bead of colour coded sealant in the matching RAL colour to the internal face of each joint before butting the next section up. The sealant at the joint is the primary weathertight line. On the wider 125mm profile, the joint face is slightly larger than on the 100mm system and the sealant bead must cover it completely and continuously.

Lock the coping to the brackets using colour coded fasteners in the matching RAL colour. Fit the left and right handed 125mm closed stopends at the run terminals and the appropriate 125mm corner pieces at every change of direction. Apply a finishing sealant bead on all external joint faces.

Where the 2m 125mm Sloping Coping Length Is Used

New-Build Housing Developments with Cavity Wall Parapets

Volume housebuilders on NHBC-registered developments across Essex, the Home Counties and the wider South East specifying 125mm sloping coping for house types with cavity wall parapets will typically order a mix of 2m and 3m sections, with 1m sections for short returns and infill. The 2m section handles the medium parapet faces typically 3m to 5m that make up a significant proportion of the perimeter on a standard house type. On a development of 30 or more units where the same house type repeats, ordering the full 125mm system from the same Chelmsford manufacturer for each phase or each unit ensures consistent profile, colour and dimensions across every plot. The aluminium sloped coping case study demonstrates this system in use at residential development scale.

Two-Storey Extensions with Prominent Parapets

Two-storey rear and side extensions in urban areas across East London, Chelmsford and the wider South East frequently include parapet coping on the flat-roofed elements. Where the parapet is at second-floor level and visible from neighbouring properties, gardens and the street, the 125mm external leg gives a more substantial, deliberate profile that reads well at height. The 2m section provides the clean, low-joint installation that a high-visibility parapet face deserves. On these projects, getting the coping right visually is as important as the weathertight performance.

Replacement Coping on Existing 125mm Installations

When replacing failed or damaged coping on a building where the original system used a 125mm external leg, the replacement must match that leg dimension. Fitting 100mm sections on a 125mm installation produces a visible mismatch in overhang and profile that is apparent from ground level. The 2m section of this 125mm system is the right replacement length for medium parapet faces on an existing building, alongside the matching corners, stopends and brackets from the same 125mm range. Ordering all replacement components from the same Chelmsford manufacturer gives the closest colour match to existing components and ensures profile consistency across the repaired section.

Residential Projects Requiring a Proportional Coping Profile

On residential and mixed-use projects where the parapet coping is a specified architectural element on a new-build house in a design-conscious street, on a roof terrace on a contemporary apartment building, or on a well-designed extension where the coping profile is part of the elevation composition the 125mm external leg gives a wider, more considered presence than the 100mm system. The 2m section, with its lower joint count than 1m sections, delivers this as a clean, uninterrupted profile across medium parapet faces. For the full 125mm system range, the Aluminium Sloping Coping collection page covers all lengths, corners, stopends and accessories in both 100mm and 125mm leg sizes.

Frequently Asked Questions

What is the difference between the 100mm and 125mm external leg, and which do I need?

The 125mm leg projects 25mm further beyond the wall face than the 100mm, giving a wider overhang, throwing water further clear, and producing a wider visual profile at parapet level. The 125mm is better suited to cavity wall parapets, wider wall constructions, and projects where the specification calls for a minimum 125mm overhang. The full selection guide is on the 125mm 1m length page. The sizing formula also differs: the 125mm system uses wall width + 220mm, while the 100mm system uses wall width + 195mm.

How do I calculate the correct size for the 125mm system?

Wall width + 220mm = the size to order. That accounts for the 125mm external leg, 75mm internal leg, and 10mm returns on each side (125 + 75 + 10 + 10 = 220). A 165mm wide wall gives 385mm. A 240mm wide wall gives 460mm. A 315mm wall gives 535mm. Do not use the 100mm system formula (wall width + 195mm) here — it gives a result 25mm too narrow for the 125mm profile.

The product shows 29 sizes. Are these 29 different run lengths?

No. Every section on this page is 2m long. The 29 sizes from 185mm to 885mm refer to the WIDTH of the coping profile the overall girth across the top from external leg tip to internal leg tip. You select the size that matches your parapet wall width using the formula wall width + 220mm. For example, a 165mm wide parapet wall needs the 385mm size, which arrives as a 2m section that is 385mm wide.

When should I use 2m sections rather than 1m or 3m?

Use 2m sections for parapet faces between 2m and 5m where the 2m length produces fewer joints than 1m sections and less waste than a 3m section. On a 4m face, two 2m sections give one joint and no waste the most efficient layout. The full length selection guide is on the 2m 100mm sloping coping page. All the same principles apply to the 125mm system.

Can I use 100mm system accessories with 125mm coping lengths?

No. The 100mm and 125mm system accessories corners, stopends, upstand stopends are fabricated to different profile dimensions and are not interchangeable. A 100mm corner on a 125mm coping run will not produce a flush, correctly aligned junction. Order all accessories in the 125mm leg size. The brackets (4mm for 2mm coping) are the same across both systems; only the profiled accessories differ.

How many brackets do I need for a 2m 125mm section?

A minimum of three brackets per 2m section: one within 150-200mm of each end and at least one intermediate at approximately 1000mm from one end. This keeps all bracket spacings within the 1000mm maximum for the 4mm bracket specification. The bracket dimension is the same for the 125mm system as for the 100mm system both use the 4mm bracket.

Part of a Complete 2mm Sloping Coping System | 125mm External Leg

This 2m length is one of three available run lengths in the 2mm aluminium sloping coping system with a 125mm external leg. All system components must match the 125mm leg size. Ordering everything from the same Chelmsford manufacturer guarantees matching profiles, consistent colour, and a system that fits correctly on site. The full 2mm sloping coping system with 125mm external leg includes:

For the full sloping coping range across both 100mm and 125mm leg sizes and 2mm and 3mm gauges, visit the Aluminium Sloping Coping collection page. For the 100mm external leg equivalent of this 2m section, see the 2mm sloping coping 2m 100mm external leg page.

Standards and Compliance

Aluminium sloping coping on flat roof parapets in the UK is specified and installed under BS 6229:2018 - Flat Roofs with Continuously Supported Flexible Waterproof Coverings. The standard covers parapet and edge detailing requirements for flat roofs including coping specification, joint treatment and fixing requirements. A 2mm aluminium sloping coping system with 125mm external leg, correctly sized to match the wall width and installed with sealant-bedded joints and properly spaced brackets, is consistent with the weathertight parapet detailing requirements of this standard.

The external grade polyester powder coat applied to all components in the 2mm 125mm sloping coping range meets the requirements of BS EN 12206-1 - Organic Coatings on Aluminium and Aluminium Alloys. The same coating specification applies consistently across all components ordered together, ensuring matching colour and durability from 1m sections to 3m sections, corners and stopends.

For NHBC-registered new-build projects, Chapter 7.1 of the NHBC Standards covers parapet wall and flat roof construction requirements. A 2mm aluminium sloping coping system with 125mm external leg, correctly specified to match the parapet wall width and installed with proper bracket fixing, is consistent with these requirements on new-build completions where the 125mm leg is the specified overhang.

 Download Our Colour Chart

Custom Fabricated Item

This is a custom-fabricated item made to your selected size and finish. Please double-check measurements before ordering. This product is non-returnable unless faulty, as explained in our Refund & Return Policy

Related System Products