Sealant under upvc window frame

5 Feb 2005
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United Kingdom
I have exterior concrete window cills and upvc windows. There's a upvc cill sitting on top of the concrete one.

There's a gap between the upvc and concrete that's been filled with silicone sealant. I removed it so I could remove the flaky paint and repaint.

A cill with silicone

A cill where I removed silicone to paint

When I removed it I saw a lot of water drops on the underside, after a night of rain. Kinda makes sense, the windows are flush sash style with drain holes in the window frames Guessing any driving rain thet gets past the outer fluffy seals head down these

So should the silicone be there? Did the wi dow fitters put it in the close the gap and make it look neater? It stops driving rain entering, but, the only place for any water ingres is then down the cavity.

Basically: should I reninstate the silicone or leave it?
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