1.5mm Aluminium Roof Edge Drip Trim | 3m Length

Fix the drip trim to the timber roof edge using corrosion resistant screws at approximately 300mm centres. Make sure the trim sits straight and tight against the deck edge. Leave a 2mm expansion gap between each 3 metre length to allow for thermal movement.

Where two lengths meet, slide a drip trim internal joiner into the back of the trim to bridge the joint. At internal corners, use a preformed 90 degree internal corner. At external corners, use a preformed 90 degree external corner. These factory formed corners give a much cleaner result than site mitring.

Once the trim is fixed, dress the first layer of roofing membrane over the fixing leg and tuck the leading edge into the drip profile. Apply a bead of colour coded sealant behind the trim if additional waterproofing is needed at the back edge. The membrane and trim together create a weathertight seal that throws water clear of the fascia.

Where Aluminium Drip Trim Is Used

Domestic Flat Roof Extensions

Single storey rear extensions, garage roofs, bay window flat roofs and porch canopies across Essex, Kent and the Home Counties all need a drip trim at the leading edge. On visible elevations where the homeowner can see the roofline, a powder coated aluminium trim in a colour matched finish gives a far better result than a standard mill finish or GRP profile.

Commercial and Industrial Flat Roofs

On larger commercial buildings, warehouses, retail units and office blocks, the 3 metre length and 1.5mm gauge provide the strength and coverage needed for long, exposed roof edges. The powder coated finish ensures the trim matches the building's aluminium fascia and coping system.

New Build Housing Developments

Volume housebuilders across the South East specify aluminium drip trims as part of the flat roof package on dormer windows, rear extensions and balcony areas. The trim integrates with the wider aluminium roofline, giving a consistent colour and material finish across fascia, soffit and roof edge.

Re-roofing and Refurbishment Projects

When an existing flat roof is stripped and recovered, the old drip trim is usually the first thing to fail. Replacing it with a 1.5mm aluminium trim during the re-roof gives the new membrane a proper edge detail and protects the investment in the new roofing system.

Schools, Care Homes and Public Buildings

On publicly funded projects where long service life and low maintenance are key requirements, aluminium drip trims meet the specification. The powder coat finish eliminates repainting, and the aluminium construction provides a 25 year plus service life with no corrosion.

Frequently Asked Questions

What is an aluminium drip trim used for?

An aluminium drip trim is fixed to the perimeter edge of a flat roof. It creates a defined drip point that throws rainwater clear of the fascia board, prevents water from tracking back under the roofing membrane, and gives the roof edge a clean, straight finish. Every flat roof should have a drip trim at every exposed edge.

How do you fit aluminium drip trim on a flat roof?

Fix the trim to the timber roof edge with corrosion resistant screws at 300mm centres. Leave a 2mm expansion gap between lengths. Use internal joiners where lengths meet and preformed corners at 90 degree turns. Dress the roofing membrane over the fixing leg and tuck the leading edge into the drip profile to create a weathertight seal.

Is aluminium drip trim better than GRP?

Aluminium is stronger, more rigid, and available in any RAL colour. GRP (fibreglass) trims are typically only available in black, white or grey, and they are more brittle, especially in cold weather. For projects where colour matching, long service life and a premium finish matter, aluminium is the better choice.

Do I need preformed corners or can I mitre on site?

Preformed corners give a much cleaner, more reliable result. Site mitring requires precise cutting, leaves exposed cut edges, and can create a weak point where water gets in. The preformed internal corner and preformed external corner are factory formed with the powder coat finish intact, so the joint is weathertight and colour matched from day one.

Can aluminium drip trim be used with EPDM and single ply membranes?

Yes. The trim is compatible with all major flat roof systems including built up felt, single ply membranes (TPO, PVC), EPDM rubber and liquid applied coatings. The membrane dresses over the fixing leg and into the drip profile regardless of the system type.

What expansion gap do I need between lengths?

Leave a 2mm gap between each 3 metre length. Aluminium expands and contracts with temperature changes, and the gap prevents the lengths from buckling in hot weather. The internal joiner bridges the gap while allowing the trim to move freely.

Aluminium vs GRP vs Plastic Drip Trims

Aluminium

Strong, rigid, and available in any RAL colour. At 1.5mm thick, this trim is substantially heavier gauge than standard profiles, providing extra rigidity on long runs. Aluminium does not crack in cold weather, does not fade in UV light, and lasts 25 years or more with no maintenance. For any project where colour matching, longevity or a professional finish matters, aluminium is the best choice.

GRP (Fibreglass)

GRP trims are widely available and competitively priced. They are a reasonable option for budget conscious projects where colour matching is not required. However, GRP is more brittle than aluminium, especially in cold conditions, and is typically limited to black, white or grey. On exposed, south facing edges, GRP can degrade over time.

Plastic (PVCu)

Plastic drip trims are the cheapest option, but they are the least durable. PVCu warps in heat, becomes brittle in frost, and fades in UV exposure. On any roof where the trim is visible or where the roofing specification calls for a long service life, aluminium or GRP is the better investment. Browse the full trims, flashings and angles collection to see the complete range.

Part of a Complete Drip Trim System

The 3 metre drip trim is the main length in the system. Ordering the trim alongside the matching joiners and corners from the same supplier ensures consistent colour, consistent profile and a professional finish at every detail. The complete drip trim system includes:

• Drip Trim 3m Length – the main roof edge trim (this product)

• Internal Joiner – flush connector between two trim lengths

• 90° Internal Corner – preformed corner for inward facing roof edges

• 90° External Corner – preformed corner for outward facing roof edges

For the wider roofline, the drip trim sits alongside aluminium fascia, aluminium copings, and aluminium roof flashing. Colour matching across all of these components from a single supplier ensures a consistent, professional finish to the entire roofline.

Standards and Compliance

Flat roof edge trims should be installed in accordance with BS 6229:2018 which covers flat roofs with continuously supported flexible coverings. The powder coat finish is applied in line with BS EN 12206-1 for powder organic coatings on aluminium. On NHBC registered new build projects, the flat roof system including edge trims should meet the requirements of Chapter 7.1 (drainage) and Chapter 7.2 (flat roofing). Getting this detail right protects the warranty, the building and the people inside it.