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

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

£172.80
(£207.36 Inc VAT)

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

When a commercial building, an NHBC-registered new-build development, or an exposed site on the Essex or Kent coast needs sloping coping, 3mm is the correct gauge and the 3m section is where the order starts. A commercial parapet of 18 linear metres takes six 3m sections with five joints and no waste. At £172.80 per section, getting the quantity planning right matters: ordering two extra sections because the run arithmetic was not worked out in advance costs over £300 in material that a non-returnable made-to-order product cannot absorb. Work out the total linear metres, divide by 3, round up, and plan the infill positions using 2m sections and 1m sections for the runs that do not divide neatly.

This is the 3mm aluminium sloping coping in a 3m length with a 100mm external leg. It is the primary commercial run length in the 3mm sloping coping system from Online Metal Store Ltd, manufactured at the Chelmsford facility. Available powder coated in any RAL colour, in 23 commercial width sizes from 510mm to 1060mm, made to order and non-returnable unless faulty.

2mm or 3mm: Getting the Gauge Right

The gauge selection is the first question to settle, because 2mm and 3mm sloping coping use different accessories, different brackets, and the size ranges are different. A full guide is on the 3mm 1m length page, but here is the short version:

Use 2mm Sloping Coping When

The project is a domestic flat roof extension, box dormer, garage or outbuilding in a sheltered residential setting. The parapet wall is a standard single-skin or modest cavity construction producing a coping girth below 510mm. The site is not exposed or elevated. Budget is a genuine consideration and the specification does not require 3mm. The 2mm sloping coping 3m length and the 125mm external leg version cover the domestic and lighter residential market.

Use 3mm Sloping Coping When

The project is commercial: office, retail, healthcare, light industrial or mixed use. The parapet wall width produces a coping girth of 510mm or above, putting it in the 3mm size range. The site is exposed or coastal. The building is two or more storeys. The NHBC specification or structural engineer's notes require 3mm. Mixing gauges on the same installation is not permitted: when 3mm is specified for the lengths, every corner, stopend and bracket must also be 3mm gauge. The 5mm coping bracket is the correct fixing bracket for the 3mm system. The 4mm bracket is for 2mm coping only.

Product Overview

This 3m section 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 greater rigidity than the 2mm equivalent, resisting wind uplift forces and thermal deformation more effectively over the service life of a commercial parapet. The built-in slope tilts the top surface toward the external face so rainwater drains off actively over the 100mm drip edge. The 23 available width sizes, from 510mm to 1060mm in 25mm increments, cover commercial parapet wall widths from approximately 315mm up to 865mm, the typical range for commercial cavity construction and wider insulated parapets. The 5mm aluminium coping bracket is the correct concealed fixing bracket for this system.

The 3m section is compatible with all accessories in the 3mm 100mm system: the 2m section and 1m section in the same profile, all four corner types, left and right handed closed stopends, stopend upstands, and the 5mm bracket. No component from the 2mm system can be substituted here.

Key Benefits

3mm Gauge for Commercial Wind Uplift and Long Service Life

The 3mm cross-section is stiffer across the profile than the 2mm equivalent. On a commercial building at any height above ground level, wind acts on the coping overhang and creates a peel force at the bracket positions. At 3mm, the coping profile resists that force more effectively across the 30-year service life expected of a commercial parapet. On a sheltered domestic extension, 2mm is perfectly adequate. On a commercial building near the Thames Estuary or on an open hillside site in Essex, 3mm is the specification that holds.

3m Sections for Minimum Joints on Long Commercial Runs

On a commercial building with a 24-metre perimeter parapet, eight 3m sections give seven joints. Twenty-four 1m sections give twenty-three. Every joint on a commercial parapet is a sealant application and a position that a facilities manager may need to inspect or re-seal at some point in the building lifetime. Reducing joint count through longer sections is sound commercial practice, and the 3m section is the most efficient choice for any straight commercial parapet run of 3m or more.

Built-In Slope on a Full 3m Profile

The slope across a 3m section runs continuously for 3000mm, which means a full 3m of active surface drainage per section. On a commercial parapet on a south-west-facing elevation in the South East, sustained driving rain in winter deposits significant volumes of water on any horizontal or near-horizontal surface. The slope carries all of it over the drip edge and clear of the wall face below, reducing maintenance requirements and protecting the external wall finish for the life of the building.

Commercial Size Range: 510mm to 1060mm

The 23 available sizes map onto commercial parapet wall construction. A 510mm coping width serves a parapet wall of approximately 315mm, which is a typical commercial cavity wall parapet. The 1060mm top size covers an 865mm wide wall, taking in wide structural commercial parapets. If your parapet girth falls below 510mm, the 2mm sloping coping system is likely the right product. If it exceeds 1060mm, contact Online Metal Store Ltd to discuss a bespoke solution for very wide commercial parapets.

Powder Coated in Any RAL Colour -- Not Anodised

Every component in the 3mm sloping coping range is finished with an external grade polyester powder coat in any RAL colour. These products are not anodised. The current product page contains two incorrect references to anodising options: these are factual errors and must be removed before publication. Powder coating is the only available finish. Ordering the 3m sections alongside the 2m and 1m infill sections, corners, stopends and brackets in the same RAL ensures all components go through the same coating batch at Chelmsford and arrive colour-matched across the full system.

5mm Bracket: The Correct Specification for 3mm Coping

The 5mm aluminium coping bracket is the correct fixing bracket for all 3mm coping systems. It is heavier than the 4mm bracket used with 2mm coping, provides greater fixing resistance, and is the right specification for the commercial and exposed-site conditions where 3mm coping is used. Fix at maximum 1000mm centres on standard commercial applications. Reduce to 750mm on exposed sites or as specified by the structural engineer where wind loading calculations have been carried out.

Technical Specifications

Material: 3mm grade aluminium

Profile: Sloping coping length

Length: 3m (3000mm)

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 the overall WIDTH of the coping profile, not the run length. All sections on this page are 3m long.

Sizing Formula: Wall width + 195mm = size to order (100mm external leg + 75mm internal leg + 10mm + 10mm returns = 195mm)

Finish: Polyester powder coating, external grade -- NOT anodised

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 Width Size

The 23 sizes from 510mm to 1060mm refer to the WIDTH of the coping profile, not the run length. Every section on this page is 3m long. The formula is the same as for the 2mm 100mm system:

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

  • Add 100mm (external leg) + 75mm (internal leg) + 10mm + 10mm (returns) = 195mm.

  • Total: wall width + 195mm = the size to order. A 315mm commercial parapet wall gives 510mm, the smallest available size. A 415mm wall gives 610mm. A 540mm wall gives 735mm. An 865mm wall gives 1060mm.

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

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

  • On site: measure across the top of an installed 3mm section from external leg tip to internal leg tip. That measurement is the size to order.

How Many 3m Sections Do You Need?

Work out the total linear metres of straight coping run for each parapet face separately. Divide by 3 and round up to get the minimum number of 3m sections for that face, then plan infill positions for any remaining length.

  • 9m face: three 3m sections, two joints, no waste.

  • 12m face: four 3m sections, three joints, no waste.

  • 10m face: three 3m sections plus a 1m section. Use the 1m section rather than cutting from a fourth 3m section and wasting 2m of a non-returnable product.

  • 7m face: two 3m sections plus a 1m section, or two 3m sections plus a 2m section for one fewer joint.

  • 20m perimeter: plan each face separately. Add up the 3m section count across all faces, then total the infill pieces. Do not include corner pieces or stopends in the linear metre calculation.

Use 2m sections for medium parapet faces and for infill pieces between 1m and 3m. Use 1m sections for the final infill piece and for genuinely short parapet sections. Always plan with 3m sections first.

The Bracket Specification: Why It Matters on a Commercial Job

Every 3mm coping installation requires the 5mm aluminium coping bracket. Not the 4mm bracket, which is for 2mm coping only. The 5mm bracket is heavier, more rigid, and provides greater resistance to the wind peel forces that act on a commercial parapet. On a building at two or more storeys, or on a site near the Essex coast where sustained wind loading is a realistic design condition rather than a theoretical exercise, using the correct bracket is part of the specification, not a detail to leave to the installer's judgment on the day.

Fix the 5mm bracket at maximum 1000mm centres on standard commercial applications, with a bracket within 150-200mm of every run terminal, corner junction and stopend position. A 3m section needs a minimum of four brackets. On exposed sites or elevated buildings where a structural engineer has carried out wind loading calculations, follow the engineered bracket centres rather than the default 1000mm maximum.

How to Install 3mm 3m Sloping Coping

Mark bracket positions along the full run before fixing anything. Fix the 5mm coping brackets at the confirmed centres with brackets within 150-200mm of every run end, corner and stopend. Confirm all brackets are flat to the wall top and properly aligned before pressing any coping into position. On a commercial run of 20m or more, a misaligned bracket early in the run accumulates into an alignment problem at the far end.

Press the 3m sections onto the brackets from the fixed terminal end of the run. Before butting each section up to the previous one, apply a continuous bead of colour coded sealant in the matching RAL to the internal face of the joint. Keep the bead continuous. On a commercial run, work systematically along the parapet and do not skip ahead of the sealant application.

Lock the coping to the brackets using colour coded metal fasteners in the matching RAL. Use metal fasteners on commercial substrate constructions. Fit the 3mm left and right handed closed stopends at the run terminals 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 3m Sloping Coping Section Is Used

Commercial Flat Roof Parapets

Commercial buildings with perimeter parapets requiring sloping coping are the primary market for this product. Offices, retail units, healthcare facilities, and light industrial buildings across Essex, East London and the wider South East use 3mm sloping coping where the parapet wall width and building specification place the project in the commercial gauge range. On a commercial building with a 24m perimeter parapet, the order is built around 3m sections as the primary length, with 2m sections and 1m sections for the faces that do not divide neatly. The aluminium coping case study shows a completed UK project using the full coping system.

NHBC New-Build Housing with Cavity Wall Parapets

On NHBC-registered developments where the house type specification calls for 3mm sloping coping on cavity wall parapets, the 3m section is the primary order length for each plot or development phase. Volume housebuilders across Essex, the Home Counties and the South East ordering the full system for each unit, including 5mm brackets, corners and stopends from the same Chelmsford manufacturer, get colour-matched components and a single-source specification that supports the NHBC warranty position. The aluminium sloped coping case study shows the sloping coping system installed across a residential development in London.

Exposed and Coastal Site Parapets

Buildings near the Essex, Suffolk or Kent coastline, and buildings on open-aspect sites across the South East where wind loading at parapet level is meaningfully above the sheltered suburban baseline, need 3mm coping specification throughout. The 3m section at 3mm gauge gives the maximum joint reduction per run while maintaining the correct specification for exposed sites. Pair with 5mm brackets at 750mm centres rather than 1000mm on these sites, and use colour coded sealant at every joint without exception.

Commercial Replacement and Refurbishment

When existing 3mm sloping coping on a commercial building reaches the end of its service life, the replacement must be 3mm. A 2mm replacement on a 3mm installation is under-specified for the site conditions that originally warranted 3mm, and it creates a profile mismatch at every junction between existing and new components. The 3m section in the 3mm 100mm system is the correct primary replacement length, ordered alongside the matching corners, stopends and 5mm brackets from the same Chelmsford manufacturer.

Frequently Asked Questions

When should I use 3mm sloping coping rather than 2mm?

Use 3mm when the project is commercial, when the site is exposed or coastal, when the parapet wall width produces a coping girth of 510mm or above, when the NHBC or structural specification requires 3mm, or when the building is at two or more storeys. For standard domestic extensions, box dormers and outbuildings in sheltered settings, the 2mm sloping coping 3m section is normally the right choice.

What size do I need for a commercial parapet wall?

Wall width + 195mm = the size to order. That accounts for the 100mm external leg, 75mm internal leg and 10mm returns each side (100 + 75 + 10 + 10 = 195). A 315mm wide commercial parapet gives 510mm, the smallest available size. A 415mm wall gives 610mm. A 540mm wall gives 735mm. The 23 sizes refer to coping widths, not run lengths. Every section on this page is 3m long regardless of the size selected.

What bracket do I need for the 3mm sloping coping system?

The 5mm aluminium coping bracket is the correct bracket for all 3mm coping. Do not use the 4mm bracket, which is for 2mm coping only. Fix at maximum 1000mm centres on standard commercial applications, with a bracket within 150-200mm of every run end, corner and stopend. On exposed sites or elevated buildings, reduce to 750mm or follow the structural engineer's specification.

How many 3m sections do I need for a commercial parapet run?

Divide the total linear metres of each straight parapet face by 3 and round up to get the 3m section count for that face. A 12m face needs four sections. A 10m face needs three sections plus a 1m infill rather than a fourth full 3m section. Calculate each face separately and add up across all faces. Do not include corner pieces or stopend lengths in the run calculation.

Is this product powder coated or anodised?

Powder coated only. The finish is an external grade polyester powder coat available in any RAL colour. These products are not anodised. The current product page contains two incorrect references to anodising options: both must be removed before the page is published. Powder coating is the only available finish across the entire Online Metal Store Ltd 3mm sloping coping range.

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

No. The 2mm and 3mm profiles have different wall thicknesses. The dimensional interface between a 2mm corner or stopend and a 3mm length will not be flush. All components on a 3mm installation must be 3mm gauge throughout: lengths, corners, stopends and upstand stopends. The brackets (4mm for 2mm, 5mm for 3mm) are also different and must match the coping gauge.

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

This 3m section is the primary run length in the 3mm aluminium sloping coping system with a 100mm external leg. A complete commercial installation needs lengths in the correct mix, 3mm corner pieces at every change of direction, 3mm stopends at every run terminal, 5mm brackets at the correct centres, sealant at every joint, and metal fasteners on commercial substrates. Order all components from the same Chelmsford manufacturer for matching profiles, consistent colour and a system that fits together 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 and both leg sizes, visit the Aluminium Sloping Coping collection page and the Aluminium Copings overview page. For the 2mm equivalent of this product, see the 2mm sloping coping 3m length with 100mm external leg.

Standards and Compliance

Aluminium sloping coping on flat roof parapets in the UK is specified under BS 6229:2018 - Flat Roofs with Continuously Supported Flexible Waterproof Coverings. This standard covers parapet and edge detailing requirements for flat roofs, including coping specification, bracket fixing and joint sealing. A 3mm aluminium sloping coping system with 5mm brackets at the correct centres and sealant-bedded joints throughout is consistent with the weathertight parapet detailing requirements of this standard. On commercial projects where a structural engineer has been engaged, bracket centres should be confirmed against the wind loading specification for the site.

The external grade polyester powder coat 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 specification forms part of a contract document or asset management plan, this standard provides a documented basis for the coating performance requirement across every component in the 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 sized components, and fully sealant-bedded joints is consistent with these requirements on new-build completions where 3mm sloping coping is the specified parapet configuration.

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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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