# Any double glazing/window know-alls?



## helston90 (10 Feb 2021)

The windows in my new house were all replaced in 2007 and appear to be in quite good nick. 

I noticed that, from the outside, the windows have sealant along the top and the two sides only - not along the bottom. 

This is replicated on all windows, suggesting that it was done on purpose - but I would have thought they'd need sealing all the way around?

I don't want to go around chucking sealant in and then causing the windows to steam or something silly. 

I have been looking for air ingress during this cold snap as it's a large, slightly chilly, bungalow.

A virtual penny for your thoughts?


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## jowwy (10 Feb 2021)

helston90 said:


> The windows in my new house were all replaced in 2007 and appear to be in quite good nick.
> 
> I noticed that, from the outside, the windows have sealant along the top and the two sides only - not along the bottom.
> 
> ...


the bottom is probably sealed on the underside to the sloping/flat window sill and the window sill would be screwed/cemented to the brickwork

you can hopefully see on this picture that the window sits on the sill to create the bottom seal and then the use sealant around the edges to seal to the walls


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## Phaeton (10 Feb 2021)

If it ain't leaking don't try to fix what isn't broke


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## JhnBssll (10 Feb 2021)

As has been said, the frame is sealed against the sill when it's installed, there won't necessarily be any visible sealant there. The mastic around the edges is only really an external seal too - there's normally a 5-10mm gap between frame and wall which is sealed with expanding foam all the way around behind the mastic to make them airtight and reduce noise ingress from outside.


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## snorri (10 Feb 2021)

helston90 said:


> I have been looking for air ingress during this cold snap as it's a large, slightly chilly, bungalow.
> A virtual penny for your thoughts?


IME it's the rubber seals on the hinged window frames that fail first, running your hand around the inside of the frame on a cold and windy night usually reveals the weak points.


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## helston90 (11 Feb 2021)

Thanks all, it does look very much like you've all described with the frame being sealed but just being out of sight.

I have had the josticks out once or twice tracing drafts and the rubber seals all seem ok. I'll go back to trying to source some good value loft insulation instead


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