uPVC windows with cills

[Tim Watts]

Hiya,

Probably a silly question - but all the uPVC windows I have fitted before have been cill-less (tiled cills already in the brickwork).

I have to fit 4 windows in my dormers that will have full size uPVC cills. The instructions recommend screwing the cills to the frame before fitting - I assume so that the cill is good fit to the frame. I've done this.

The instructions do not mention adding a bead of silicone between the two though. So I was wondering if this is the best way?

There are drain holes in the frame - where these are, right at the front outside edge, the slope of the cill already leaves a big gap, so easy to avoid bunging these up.

I would be inclined to run a bead of silicone along the centre ridge of the frame which bears onto the flat part of the cill. That would also protect the frame fixing screws and their holes which are roughly at the centre line.

Any reason I should not use sealant?

Cheers,

Tim

[harry]

No reason at all s long as you seal it to keep condensation out and to let any water that gets in drain out. The main thing to watch is that they are flat, vertical and the fixings don't distort them, (ie packings round the fixing screws You can get plastic packings with slots in from screwfix ideal for the job.. I use fixing foam as well to make draught proof.

[Tim Watts]

Cheers Harry,

Yes - I use packers and finish the gaps with foam followed by sealant on the outside.