3mm Aluminium Sloping Coping – 1m Length | 100mm External Leg - Online Metal Store Ltd

3mm Aluminium Sloping Coping – 1m Length | 100mm External Leg

£73.22
(£87.86 Inc VAT)

3mm Aluminium Sloping Coping – 1m Length | 100mm External Leg

The size range on this product, 510mm to 1060mm, tells you exactly what this product is for. A 510mm coping width corresponds to a parapet wall of approximately 315mm wide. You do not find walls that wide on a domestic single-skin rear extension. You find them on cavity wall commercial construction, on wider residential parapet builds, on NHBC new-build housing with insulated parapets, and on commercial buildings where the parapet construction adds up to a greater overall wall thickness. And you specify 3mm rather than 2mm because on a commercial building, an exposed coastal site, or any project where the coping is expected to perform for 25 to 30 years without intervention, the heavier gauge is the correct long-term choice.

This is the 3mm aluminium sloping coping in a 1m length with a 100mm external leg. It is the commercial-spec counterpart to the 2mm version in the same profile and leg size heavier gauge, wider size range, higher price, and the right product for projects where 2mm is not the correct specification. Manufactured in Chelmsford, Essex, powder coated in any RAL colour, and available in 1m, 2m and 3m lengths across the full 23-size commercial width range.

2mm or 3mm Sloping Coping: The Gauge Decision

Both gauges are available across the full sloping coping system at Online Metal Store Ltd. The profile, slope angle and installation method are identical. The gauge choice follows the same logic as for flat coping, and the same criteria that apply to the flat coping system apply here:

Use 2mm Sloping Coping For

Domestic flat roof extensions and parapets in sheltered suburban or rural settings. Box dormers and flat-roofed outbuildings where 2mm is the appropriate gauge for the wall width and exposure. Residential projects where the parapet is low, the wall is narrow, and the site is not in a high wind speed zone. Budget-constrained projects where 2mm meets the specification. The 2mm sloping coping 1m length (100mm external leg) and the 2mm 125mm external leg version cover the domestic and lighter residential market.

Use 3mm Sloping Coping For

Commercial buildings where the structural or architectural specification calls for 3mm. NHBC-registered new-build developments where the house type parapet detail specifies the heavier gauge. Exposed and coastal sites, including buildings within a few kilometres of the Essex, Suffolk or Kent coast, and open-aspect sites where the wind loading at parapet height is meaningfully higher than at ground level. Buildings of two storeys or more where the parapet is elevated and the wind uplift forces are greater. Any project where the parapet wall width falls in the 315mm to 865mm range, which puts the coping girth in this product's 510mm to 1060mm size range. The 3mm sloping coping left handed stopend and the 3mm coping bracket confirm that the full 3mm system is available from the same Chelmsford source.

Mixing gauges on the same installation is not recommended. A 2mm corner or stopend on a 3mm length run will not produce a correctly aligned junction. Every component in the installed system must be the same gauge.

Product Overview

This 1m length is part of the Online Metal Store Ltd 3mm aluminium sloping coping system with a 100mm external leg, fabricated at the Chelmsford facility. The 3mm gauge provides the additional rigidity and wind uplift resistance that commercial and exposed-site parapets require. The built-in slope tilts the profile toward the external face so rainwater drains actively off the coping surface rather than ponding or draining back toward the roof. The 100mm external leg provides the overhang and drip detail; the 75mm internal leg returns down the inside face of the parapet. The 23 available width sizes, from 510mm to 1060mm in 25mm increments, cover commercial parapet wall widths from approximately 315mm up to around 865mm.

The 1m length serves the same role in the 3mm system as in the 2mm system: infill at the end of a longer commercial parapet run that does not divide neatly into 3m sections, short parapet sections on complex layouts, and tight-access installation positions. The 3m length in the same 3mm 100mm system is the primary length for long commercial runs, with the 2m length covering medium spans. All three lengths use the same system accessories and are powder coated in any RAL colour.

Key Benefits

3mm Gauge for Commercial Wind Uplift Resistance

On a commercial building at any height above ground level, wind pressure on a parapet coping face is significantly higher than on a domestic extension at eaves level. The peel force generated when wind gets under the overhang of a coping profile increases with both height and site exposure. The 3mm gauge provides greater cross-sectional rigidity than the 2mm equivalent, which means the coping profile resists deformation and peel more effectively over the service life of the installation. On a commercial project where the parapet is expected to perform without intervention for 25 to 30 years, specifying 3mm rather than 2mm is the correct long-term decision.

Built-In Slope for Active Surface Drainage

The sloped top surface tilts toward the external face, directing rainwater actively off the coping and over the 100mm external leg drip detail. This is particularly relevant on a commercial building where the parapet faces may be south-west-facing and exposed to the prevailing weather across the South East. Active surface drainage reduces the risk of water penetrating joints under standing water pressure, prevents staining on the wall face below, and reduces freeze-thaw stress at joints during cold weather. The slope is built into the 3mm aluminium profile and requires no additional work on site.

23 Commercial Width Sizes, 510mm to 1060mm

The 23 available width sizes cover commercial parapet wall widths from approximately 315mm to 865mm. This is the wall width range produced by commercial cavity wall construction, insulated parapet builds, structural steel parapets, and wider residential builds where the parapet construction adds up to a greater overall wall thickness. If your parapet wall width falls below 315mm, the 2mm sloping coping system with its smaller size range is likely the more appropriate product. If it exceeds 865mm, contact Online Metal Store Ltd to discuss bespoke options for very wide commercial parapets.

Powder Coated in Any RAL Colour

The finish on every component in the 3mm sloping coping range is an external grade polyester powder coat available in any RAL colour. On a commercial project where the coping colour is specified in the contract documents, ordering all system components lengths, corners, stopends and brackets in the same RAL from the same Chelmsford batch ensures full colour consistency across the installed perimeter.

UK Manufactured for Commercial Programme Reliability

Made to order at the Online Metal Store Ltd facility in Chelmsford, Essex, with UK manufacturing lead times that support commercial construction programmes. For commercial projects in Essex, East London, the South East and the wider UK, the full 3mm sloping coping system can be ordered as a package and delivered on a programme that keeps the coping installation on the critical path to watertight. Non-returnable as a made-to-order custom fabrication.

Technical Specifications

Material: 3mm grade aluminium

Profile: Sloping coping length

Length: 1m (1000mm)

External Leg: 100mm

Internal Leg: 75mm

Width Sizes Available: 510mm, 535mm, 560mm, 585mm, 610mm, 635mm, 660mm, 685mm, 710mm, 735mm, 760mm, 785mm, 810mm, 835mm, 860mm, 885mm, 910mm, 935mm, 960mm, 985mm, 1010mm, 1035mm, 1060mm (23 sizes in 25mm increments)

Wall Width Range Served: Approximately 315mm to 865mm (wall width + 195mm = coping size)

Size Note: The "size" refers to coping WIDTH, not run length. All lengths are 1m; the size matches your wall width. Formula: wall width + 195mm = size to order.

Finish: Polyester powder coating, external grade

Colour: Any RAL colour to order

Compatible Bracket: 5mm Aluminium Coping Bracket. NOT the 4mm bracket (which is for 2mm coping only)

Fabrication: Made to order - non-returnable unless faulty

Country of Manufacture: United Kingdom (Chelmsford, Essex)

Calculating the Correct Width Size

The 23 sizes from 510mm to 1060mm on this page refer to the overall WIDTH of the coping profile, not the run length. All lengths on this page are 1m long. The size you select must match the overall girth of your parapet wall. The formula is identical to the 2mm 100mm system:

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

  • Add the external leg (100mm) and internal leg (75mm) = 175mm.

  • Add both 10mm returns = 20mm.

  • Total: wall width + 195mm = the size to order. A 315mm commercial parapet wall gives 315 + 195 = 510mm, the smallest available size. A 540mm wall gives 735mm. An 865mm wide wall gives 1060mm, the largest standard size.

  • If the calculated size falls below 510mm, your wall is likely in the domestic 2mm system range. Verify the gauge specification before ordering.

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

  • Quickest site check: measure the overall width of an installed 3mm coping length directly across the top surface. That measurement is the size to order.

The Correct Bracket: 5mm, Not 4mm

Every 3mm aluminium coping system, whether sloping or flat, requires the 5mm aluminium coping bracket. The 4mm bracket is the correct fixing for 2mm coping only. This is not a minor distinction: the 5mm bracket is heavier, provides greater fixing resistance, and is the appropriate specification for the commercial and exposed-site conditions where 3mm coping is typically used. Using a 4mm bracket on a 3mm coping installation on a commercial building or exposed site is an under-specification that could contribute to bracket failure under wind loading.

For 3mm sloping coping, fix the 5mm brackets at maximum 1000mm centres on standard commercial applications. On exposed sites, elevated buildings, or where wind loading calculations have been carried out by a structural engineer, reduce to 750mm centres or as engineered. Always position a bracket within 150-200mm of every run terminal, corner junction and stopend position. For commercial projects, bracket centres should be confirmed against the wind loading specification for the site where relevant.

1m, 2m or 3m Length: Choosing for a Commercial Run

The selection logic for a 3mm commercial installation follows the same principles as for the 2mm system. Plan the run with 3m lengths first fewer joints, less sealant, a cleaner installed line, and lower overall material cost for the same linear run. Use 2m lengths for medium spans and as the first infill step when the run does not divide neatly into 3m sections. Use the 1m section for short parapet sections that cannot be served by longer lengths, for the final infill piece at the end of a longer run, and for tight-access positions where a 3m section is difficult to manoeuvre at height on a commercial building.

On a 22m commercial parapet run, for example, seven 3m lengths plus one 1m section gives 22m with eight joints. Ordering eight 3m lengths and cutting 2m of waste from the last section costs more in material on a made-to-order product and generates waste. The 1m section is the right final piece for this run.

How to Install 3mm Sloping Coping Lengths

Mark the bracket positions before fixing anything. Fix the 5mm aluminium coping brackets at the confirmed centres maximum 1000mm, or as engineered on exposed or elevated sites with a bracket within 150-200mm of every run terminal, corner junction and stopend. For a 1m length, you need a minimum of two brackets at approximately 700-800mm apart. On a commercial project where wind loading has been calculated, the engineered bracket centres take precedence.

Press the 3mm coping lengths onto the brackets working from the fixed terminal end of the run. Before butting each length up to the previous one, apply a continuous bead of colour coded sealant in the matching RAL colour to the internal face of the joint. On a commercial parapet the sealant bead is the primary weathertight line at every run joint. A complete, unbroken bead at each joint is essential, do not work ahead of the sealant application on a long commercial run.

Lock the coping to the brackets using colour coded metal fasteners in the matching RAL colour. Use metal fasteners rather than timber fixings on commercial substrate constructions. Fit the left and right handed 3mm closed stopends at the terminal ends and the appropriate 3mm corner pieces at every change of direction. Apply a neat finishing sealant bead on all external joint faces.

Where the 3mm 1m Sloping Coping Length Is Used

Infill Sections on Commercial Parapet Runs

On a commercial building with a perimeter parapet where the run does not divide neatly into whole 3m sections, the 1m length provides the precise infill piece. On a 16m parapet run, five 3m lengths plus one 1m section gives 16m with six joints the most efficient layout with minimal waste. On a made-to-order commercial product at a higher price point than the 2mm equivalent, keeping waste to a minimum through careful run planning is good practice.

Complex Commercial Parapets with Multiple Short Returns

Commercial buildings rarely have simple four-sided parapets. Stepped parapets, plant room enclosures, lift shaft caps, service duct covers and stairwell overruns all produce short parapet sections that require coping but cannot be served by a full 3m length without substantial cutting. On a commercial building in Chelmsford, Brentwood, Basildon or across East London, the 1m section is the right product for these short-return details within a predominantly 3m commercial installation. All sections on the same building should use the same 3mm gauge, the same leg size and the same RAL colour.

New-Build Housing Developments with Wider Parapets

NHBC-registered housebuilders on developments across Essex, the Home Counties and the South East specifying 3mm sloping coping for house types with cavity wall parapets will typically order a mix of 3m and 1m sections per plot or per phase, depending on the parapet layout. The 1m sections handle the infill positions within each plot's parapet run. Ordering the full system for each plot from the same Chelmsford manufacturer, including the 5mm brackets, stopends and corner pieces, ensures consistent colour and profile across every unit on the development.

Exposed and Coastal Site Parapets

On buildings within a few kilometres of the Essex or Kent coastline, or on open-aspect sites where the wind loading at parapet height is above the norm for sheltered suburban construction, the 3mm gauge is the correct specification for every component in the coping system. The aluminium sloped coping case study shows the sloping coping system in use on a residential development, demonstrating the system's performance in real-world UK conditions.

Frequently Asked Questions

When should I use 3mm sloping coping instead of 2mm?

Use 3mm when the project is commercial, when the site is exposed to higher wind loads, when the NHBC or structural specification calls for 3mm, when the parapet wall width falls in the 315mm-865mm range (510mm-1060mm coping girth), or when the building is on a coastal or elevated site. For straightforward domestic rear extensions with sheltered aspects and narrower parapet walls, the 2mm sloping coping system is the appropriate choice. The price difference between 2mm and 3mm (the 3mm 1m section is more than double the 2mm equivalent) reflects the material and specification difference.

What size do I need for my commercial parapet?

Wall width + 195mm = the coping size to order. A 315mm commercial cavity wall parapet gives 510mm, the smallest available size. A 440mm wide wall gives 635mm. A 715mm wide wall gives 910mm. If the calculated size falls between two available sizes, order the next size up. Remember: the 23 sizes refer to coping width, not run length. All sections on this page are 1m long regardless of the size selected.

What bracket do I use with 3mm sloping coping?

The 5mm aluminium coping bracket is the correct specification for all 3mm coping systems, including 3mm sloping coping. Do not use the 4mm bracket, which is specified for 2mm coping only. On commercial or exposed-site projects, the 5mm bracket at 1000mm maximum centres is the default; on sites where wind loading calculations have been carried out, use the engineered bracket centres. The 5mm coping bracket is available from the same range.

Can I mix 3mm and 2mm components on the same parapet installation?

No. The 2mm and 3mm coping profiles have different wall thicknesses, which means the dimensional interface between a 2mm accessory and a 3mm length will not produce a flush, correctly aligned junction. Every component on a 3mm installation lengths, corners, stopends, upstand stopends must be 3mm gauge. Using a 2mm corner or stopend in a predominantly 3mm run to save cost on an accessory undermines the specification of the system at its most vulnerable points.

When should I use 1m sections on a commercial parapet?

Use the 1m length as the infill section at the end of a longer run that does not divide neatly into 3m sections, for genuinely short parapet sections such as return walls, plant room enclosures, or service duct covers, and for tight-access positions where a 3m length is difficult to handle safely at height on a commercial building. For long uninterrupted commercial parapet runs, plan with 3m lengths first. On a commercial project the additional joints from over-ordering 1m sections increase the number of sealant points that need to be maintained over the building lifecycle.

Is this product suitable for NHBC new-build projects?

Yes. The 3mm aluminium sloping coping system is consistent with NHBC Standards Chapter 7.1 requirements for parapet wall and flat roof construction on new-build housing where a heavier gauge coping is specified. On NHBC-registered developments where the house type parapet detail calls for 3mm sloping coping, this product and all associated 3mm system accessories are the correct specification. Ordering all system components from the same UK manufacturer with consistent profile and colour supports the warranty position and ensures there is a traceable single-source specification for the installed coping system.

Part of a Complete 3mm Sloping Coping System | 100mm External Leg

This 1m length is one of three available lengths in the 3mm aluminium sloping coping system with a 100mm external leg. Every accessory in this system must match the 3mm gauge. Ordering all components from the same Chelmsford manufacturer guarantees consistent profiles, matching colours, and a system that fits together correctly on site. The full 3mm sloping coping system with 100mm external leg includes:

For the full sloping coping range across both 2mm and 3mm gauges, visit the Aluminium Sloping Coping collection page and the Aluminium Copings overview page. For 2mm sloping coping, the 2mm sloping coping 1m length (100mm leg) is the lighter-gauge equivalent for domestic and sheltered-site installations.

Standards and Compliance

Aluminium sloping coping systems on flat roof parapets in the UK are specified under BS 6229:2018 - Flat Roofs with Continuously Supported Flexible Waterproof Coverings. The standard covers parapet and edge detailing requirements including coping specification, fixings and joint treatment. A properly installed 3mm aluminium sloping coping system with correctly sealant-bedded joints, correctly specified 5mm brackets at appropriate centres, and correctly gauged accessories throughout is consistent with the weathertight parapet requirements of this standard.

The external grade polyester powder coat finish applied to all Online Metal Store Ltd 3mm sloping coping components meets the requirements of BS EN 12206-1 - Organic Coatings on Aluminium and Aluminium Alloys. On a commercial project where the coping forms part of a contract document or lifecycle maintenance plan, the documented coating standard across every system component provides a traceable specification for the installed system.

For NHBC-registered new-build projects, Chapter 7.1 of the NHBC Standards covers parapet wall and flat roof construction requirements. A 3mm aluminium sloping coping system, with 5mm brackets correctly spaced and all joints sealant-bedded, is consistent with these requirements on new-build completions where the heavier gauge sloping coping has been specified.

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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

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