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Windows & Door fitting

Advice on Window Sills – uPVC vs Concrete vs Brick-Built vs no sill?

Mike_k 08/08/2025 - 9.42 AM

I’m replacing two windows and making a bigger opening for one of them (currently it's a tiny shower window flush with external wall and no cill) and ran into a bit of a problem around the external sills. 1. The smaller window already sits on a concrete sill (old, chipped paint, but structurally okay). 2. For the larger window, I originally specced a uPVC sill, but realised it adds 30mm to the frame height, which throws off the indoor alignment, so decided against that I looked into getting a precast concrete sill, but the cost of delivery around London is more than double the sill itself. We’re not that fussed about how the sill looks from outside, the priority is stopping rain from pooling and reducing damp risk. So now I’m wondering - what are my options? Brick sill? No cill? Anything I haven't considered?

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1 Answer

Maj Windows & Glazing

Rating: 4.9 out of 5
Birmingham
Repair existing concrete sill – fill chips, repaint. • Brick-on-edge sill – use engineering bricks with slope and drip groove. • Cast in place concrete sill – pour on site with slope. • Aluminium sill cover – slim, good water shedding, easy to fit.
Answered11 August 2025
0