Exterior window sill flashings — coated steel, cut and folded to size

Rain makes the work of a window’s lower edge easy to see. An external sheet metal sill collects water running down the glass and directs it beyond the façade. In a new home or the refurbishment of an older building, this small but necessary component combines wall protection with a neat finish around the window.

A sloping, shaped surface carries water towards the front edge, and the drip helps droplets detach from the sill’s underside. Rainwater is thus discharged in front of the wall face, reducing local wetting and water stains. This protection is especially useful on light-coloured render, where runoff marks quickly become visible. The sill works together with its side terminations and the seal at the frame to create a carefully finished window detail.

Custom fabrication gives considerable flexibility during an insulation upgrade. Added insulation changes the depth of the window recess, which the new finish needs to cover correctly. Sheet metal can be formed to the required sill depth, length and folds according to a drawing. This makes it easier to fit both a wide shopfront window and a narrow utility-room opening. Each receives a component suited to its actual proportions and the façade thickness.

Coated steel sheet combines a thin material section with useful stiffness provided by its folds. The finished sill is light compared with a solid stone slab, making it easier to carry and position at the window. The coating protects the metal surface, and a version selected for the building’s exposure is suitable for outdoor service. It is also a practical option for a workshop or small office requiring a durable, neat flashing at a reasonable fabrication cost.

The sill colour can subtly connect the window frames with the roof and other flashings. A dark shade defines the window line against a light wall, while a light one creates a calmer effect. Repeated profiles and finishes give a clear rhythm to several openings on one elevation. Where a garage has been added, the same sheet metal can also connect the old and new parts of the building visually. A small surface is enough to give the windows a distinct, carefully completed lower edge.

The smooth surface is convenient to clean periodically of dust and deposits. This helps maintain an area visible from inside whenever the window is opened. When refurbishing a single opening, a suitable flashing can be made without changing the entire façade concept. Metal sills are therefore useful for comprehensive house insulation and smaller renovation jobs alike, completing the finish with a specific, functional component.

Order made-to-measure sills from SteelProfil at favourable prices and fit them to your windows. Our broad materials range includes first and second grade, with many items available from stock. Use our promotions to combine new flashings with the remaining materials for your façade renovation.