Timloc External Cowl – 255 x 160 (1 pcs)

The Timloc 255 x 160mm external cowl is a straightforward fix for one of the more overlooked problems on a finished build: the gap between decent ventilation and a room that feels like a wind tunnel every time the weather turns. Fit one of these over an external wall vent and you get the airflow you need without cold air just blasting straight through. It’s the kind of thing that gets ignored until a homeowner starts complaining about draughts, at which point you wish you’d fitted it during the build.

Timloc have been making ventilation components for UK construction for decades, and this cowl sits comfortably in their range of external wall accessories. The 255 x 160mm size is a standard fit for most rectangular wall vent openings, making it a straightforward swap or new installation on cavity walls, solid walls, and most masonry construction. The louvred face deflects wind and rain while still letting air move freely behind it, which is the whole point.

Where the Timloc 255 x 160mm External Cowl Gets Fitted

You’ll see these going on during the finishing stages of new builds and refurbs alike. Bricklayers fit them as part of the external skin, plasterers and dry liners call them in when the internal vent grille is going on the opposite face, and building control sometimes needs them ticked off as part of ventilation compliance. They’re particularly useful on sheltered or north-facing walls where condensation and windblown rain are a genuine concern.

The brown and terracotta colour options make a real difference on brick elevations. A white plastic cowl on a traditional red-brick house looks like an afterthought. Matching the finish to the brickwork colour means the cowl does its job without drawing attention to itself, which is usually what the client wants.

Installation Notes

Installation is clean and quick. The cowl is designed to sit flush against the external face of the wall, fixed around the vent aperture. Most fixers bed these in with a suitable exterior-grade sealant or mortar depending on the substrate, and the profile keeps things neat against brickwork or render. No fiddly assembly, no specialist tools required. At this price point it makes sense to specify these as standard rather than leaving the vent open and dealing with draught complaints later.