2mm Aluminium Sloping Coping – 90° Internal Corner | 100mm External Leg

Corners are usually where a coping job starts to look good or starts to fail. On flat roof parapets, garden walls and boundary walls across Chelmsford, Brentwood, Colchester, Basildon and East London, a weak internal corner can let driving rain sit in the wrong place, stain the wall below, or leave an awkward gap that never looks quite finished.

This 2 mm aluminium sloping coping corner gives you a properly formed 90 degree internal junction, so two coping runs can meet cleanly without bodged cuts on site. It is made for roofers, builders, homeowners and contractors who want the corner detail to look sharp and deal with UK weather properly from the start.

Product Overview

The 2 mm aluminium sloping coping corner is a pre formed internal corner piece designed to join two runs of aluminium sloping coping at an inward facing 90 degree angle. It is used where a parapet or wall returns back on itself, helping the coping line stay continuous and neat while keeping rainwater moving away from vulnerable wall edges.

Online Metal Store Ltd fabricates this product in Chelmsford, Essex, with a 100 mm external leg and a powder coated finish available in any RAL colour. It is made to work as part of a complete aluminium copings system, so the corner, coping lengths and related fittings can be ordered together for a consistent profile and colour match.

For installation, pair the corner with the right coping lengths, matching fixings and colour coded sealant so the joint is sealed properly. Where the same roofline includes abutments or detail work, it can also sit alongside aluminium roof flashing and other trims from the same supplier.

Key Benefits

A Neat 90 Degree Internal Junction

The main job of this coping corner is to give the internal return a clean, factory formed finish. Instead of trying to cut and dress two straight coping lengths into a corner on site, you have got a proper corner piece that keeps the line tidy and reduces the chance of an uneven joint.

Built for UK Rain, Frost and Damp Weather

Aluminium is well suited to roof edge and parapet work in the UK because it resists corrosion and handles damp conditions, frost cycles and regular rainfall better than many traditional materials. On exposed walls in Essex, Kent, London and coastal areas, that matters because corners take a lot of weather from more than one direction.

Sloping Profile Helps Rainwater Run Off

The sloping profile is designed to encourage water to move away from the parapet edge rather than sitting across the top of the wall. That is useful on flat roof extensions, terraces and boundary walls where ponding near a corner can create staining, moss growth or long term water ingress concerns.

Powder Coated in Any RAL Colour

The corner can be powder coated to any RAL colour, which helps the coping system match windows, doors, fascia, cladding or the rest of the roofline. Anthracite grey, black, white and bespoke project colours can all be specified when the building needs a more controlled architectural finish.

Lightweight and Easier to Handle on Site

At 2 mm thickness, the aluminium gives a practical balance of strength and handling. It is easier to lift, position and align than heavy stone coping pieces, especially on small domestic extensions, terrace roofs and awkward parapet runs where site access is tight.

UK Manufactured with Fast Delivery

The product is manufactured in Chelmsford, Essex, which gives UK buyers a clearer route for product support, colour matching and project led advice. That is helpful when a roofer in Billericay, a builder in Braintree or a homeowner in Southend needs a corner that matches the rest of the coping order.

Works as Part of a Complete Coping System

A coping corner performs best when it is ordered with the matching lengths, brackets, sealant and related details. Buying the complete system from one supplier helps reduce mismatched colours, awkward profiles and missing components that slow down work on site.

Technical Specifications

Product Type: Pre formed 90 degree internal corner for aluminium sloping coping.

Material: 2 mm architectural grade aluminium.

Profile: Sloping coping internal corner.

Corner Angle: 90 degrees internal.

External Leg: 100 mm external leg.

Internal Leg: Not clearly shown on the current product listing. Add the confirmed internal leg measurement before publishing the final live copy.

Available Sizes: 185 mm, 210 mm, 235 mm, 260 mm, 285 mm, 310 mm, 335 mm, 360 mm, 385 mm, 410 mm, 435 mm, 460 mm, 485 mm, 510 mm, 535 mm, 560 mm, 585 mm, 610 mm, 635 mm, 660 mm, 685 mm, 710 mm, 735 mm, 760 mm, 785 mm, 810 mm, 835 mm, 860 mm and 885 mm.

Finish: Powder coated to any RAL colour.

Base Price: From £57.60 ex VAT, £69.12 inc VAT on the current live listing.

Manufactured In: Chelmsford, Essex, United Kingdom.

Custom Fabrication: Made to selected size and finish. Non returnable unless faulty, subject to the live refund policy.

Compatible System: Online Metal Store Ltd aluminium sloping coping system and related roof edge components.

Choosing the Right Size / Width / Thickness

Choose the coping corner size to match the coping width used across the rest of the parapet run. The corner should not be treated as a separate decorative item. It needs to match the coping profile, wall width and finish so the system lines through properly.

·         Use the same width as the straight coping lengths on the same parapet run.

·         For domestic extensions and garden walls, measure the finished wall width including render, cladding or coping substrate, not just the blockwork below.

·         For Victorian terraces and Edwardian semis, check whether old walls are out of square before ordering the corner size.

·         For commercial flat roofs, schools and care homes, confirm the specification against the roof drawing and waterproofing upstand detail.

·         Use 2 mm where the matching coping system is 2 mm. Do not mix 2 mm and 3 mm components on the same visible run unless the project drawing calls for it.

·         If the project has wider parapets, heavier use areas or a separate specification for 3 mm coping, consider the matching 3 mm internal corner instead.

How to Install / How to Fit

Start by checking the parapet substrate is level, stable and ready to receive the coping system. Dry fit the straight coping lengths and this corner before applying sealant, because the internal junction needs to line up with the fall direction and the rest of the visible edge.

Set out the straight coping run first, then position the internal corner so both adjoining lengths meet without forcing the profile. If the roofline includes a matching outward return, use the correct 90 degree external coping corner rather than cutting an internal corner to suit.

Use the specified fixing method for the coping system and keep fixings compatible with the substrate. Where timber backing is used, match the finish with colour coded fasteners for timber. Where metal backing is used, use colour coded fasteners for metal so the installation looks consistent.

Seal the joint carefully with colour coded sealant, especially at the internal junction where water can collect if the detail is rushed. Tool the sealant neatly, wipe away excess before it skins, then check the joint from both sides so there are no gaps, twists or visible steps in the coping line.

Before handover, run a visual check along the coping line from ground level and roof level. The corner should look like part of the system, not an afterthought. That is the standard buyers expect on domestic extensions, commercial buildings and high value residential work across the South East.

Where Aluminium Coping Corner Is Used

Flat Roof Parapet Returns

This product is used on flat roof parapets where two coping runs meet at an inward facing corner. It is especially useful on rear extensions in Chelmsford, Brentwood and East London, where a neat roof edge matters as much as the waterproofing detail. Pair it with the matching aluminium copings range for a consistent finish.

Domestic Extensions and Renovations

Homeowners upgrading an older roof edge often want something smarter than cracked stone, patched lead or tired mortar joints. A powder coated aluminium corner gives a clean modern finish, especially when the same RAL colour is used across fascia, soffit, windows or doors.

Commercial Rooflines and Apartment Blocks

On commercial units, apartment blocks and mixed use buildings, internal parapet corners need to look tidy and cope with regular exposure. The pre formed corner helps the installer keep the line straight and reduces the need for time consuming on site forming. For larger schemes, link the product page to the coping case study to build trust.

Boundary Walls and Garden Walls

Aluminium coping is not just for roof edges. It can also be used on rendered boundary walls, garden walls and entrance walls where standing water would otherwise sit on the top surface. The corner keeps the return neat and helps the full wall capping look deliberate.

Roof Edge Systems with Flashings and Trims

Where the same roof edge includes wall abutments, flat roof trims or detailed junctions, the coping corner should be specified with matching trims, flashings and angles. Using one supplier helps avoid small finish differences that become obvious once the job is complete.

Frequently Asked Questions

Do I need an internal or external coping corner?

You need an internal coping corner where the wall or parapet turns inward and two coping runs meet inside the angle. You need an external coping corner where the wall turns outward around the outside of a corner. The two are not interchangeable, so check the roof plan or stand on site and identify the direction of the return before ordering.

How many aluminium coping corners do I need?

You usually need one coping corner for each 90 degree corner in the parapet or wall run. Count internal and external corners separately because they use different formed components. On a simple rectangular flat roof, you will normally have external corners, while more complex returns, courtyards and roof wells may need internal corners as well.

Can this coping corner be powder coated to match my project?

Yes. This aluminium coping corner can be powder coated to any RAL colour, so it can match the straight coping lengths, fascia, soffit, cladding, doors or window frames. For the best finish, order the complete system in one colour batch where possible.

Is aluminium better than lead or stone for coping corners?

Aluminium is lighter than stone and easier to handle on site, while still giving strong weather resistance and a clean modern finish. Lead can still be useful on some listed or conservation projects, and stone may suit traditional buildings, but powder coated aluminium is often the more practical choice for modern UK roof edges and parapets.

What size aluminium coping corner should I order?

Order the corner in the same width as the matching straight coping lengths. Measure the finished wall width including render, insulation, cladding or backing build up. If the wall is out of square or has an unusual detail, confirm the size before ordering because custom fabricated items are normally not returnable unless faulty.

Does the corner need sealant?

Yes, the joint should be sealed as part of the coping system. Use a suitable colour coded sealant at the junctions and follow the system fixing guidance. A neat seal at the internal corner helps protect the parapet from water ingress and gives the finished roof edge a cleaner appearance.

Comparison Section

Aluminium Coping Corner

A powder coated aluminium coping corner is the strongest fit for most modern parapet and roof edge projects where the buyer wants a clean, lightweight and low maintenance finish. It works well on domestic extensions, commercial buildings, schools, care homes and apartment blocks because it can be colour matched and ordered as part of a complete system.

Lead Dressed Corner Detail

Lead still has a role on listed buildings, heritage sites and conservation projects where traditional materials are required by the specification or conservation officer. It is more labour intensive and needs skilled installation, so it is not always the best option for a modern powder coated roofline where crisp architectural detailing is expected.

Stone or Concrete Coping Corner

Stone and concrete coping corners suit some traditional garden walls and older buildings, but they are heavier, harder to handle and can suffer from cracking, staining or open mortar joints over time. Aluminium is often easier for roofers and builders to install when the goal is a lighter, colour matched parapet system.

For buyers comparing complete systems, the product page should link back to the main aluminium coping collection so they can move from the corner to straight lengths, wider coping options and related accessories without leaving the buying journey.

Part of a Complete System

This is not a stand alone decorative part. It should be presented as one piece within a complete aluminium coping system, especially because buyers often forget corners, sealant, fixings and companion details until installation starts.

·         Aluminium sloping coping lengths for the main parapet run.

·         90 degree external coping corners for outward facing returns.

·         125 mm leg internal corner where a deeper external leg is required.

·         3 mm internal corner where the coping specification calls for thicker aluminium.

·         Colour coded sealant for sealed joints and neat finishing.

·         Colour coded timber fasteners where the fixing substrate is timber.

·         Colour coded metal fasteners where the fixing substrate is metal.

·         Roof flashings, trims and angles where the roof edge includes abutments or adjacent detailing.

The live page should link to the 125 mm leg internal coping corner, the 3 mm aluminium internal coping corner, the colour coded sealant and the wider roof accessories collection so the buyer can build the full order in one session.

Standards and Compliance

For powder coated aluminium used in architectural applications, reference BS EN 12206-1:2021 as the current British Standard covering coating of aluminium and aluminium alloys with thermosetting coating powder. This helps keep the page factual and avoids the incorrect anodising language that appears on some older product pages.

For flat roof context, reference BS 6229:2025 because it supersedes BS 6229:2018 and covers recommendations for the design, construction and maintenance of flat roofs with continuously supported roof coverings.

For new build work, mention NHBC Standards where relevant because parapet, roof edge and weathering details need to protect the warranty, the building and the people inside it. Keep this section practical and avoid claiming formal compliance unless Online Metal Store Ltd has the relevant test data or project specification to support it.