Since I bought my house 7 months ago, I have noticed this in the master bedroom, bathroom (only slightly) and in part of the bay window. In the master bedroom, there is about an inch of the black seal missing. Could this be causing this? On every window that I've mentioned, a small part of the black seal has come away from the window. Does the seal get replaced, or are the uPVC windows no good?

I noticed during the summer that the condensation was present then. I thought installing central heating might have solved this (the property never had central heating prior to me buying the place). The uPVC windows were put in 12 years ago in 1994.


Cheers :-).

There are different seals in a double-glazed window unit.
Firstly, there are 2 pieces of glass separated by an aluminium (usually) spacer and sealed all around the edge with what usually looks like an insulating type of tape. Often this is black.

This sealed unit is then held inside a UPVC frame and this will also have rubber seals between the glass and the UPVC and the glass to keep the rain, condensation and wind out.

The sealed glass unit has dessicant crystals in the aluminium spacer to keep the air between the 2 glass pieces dry (and so stop condensation).
If the seal on the glass unit has failed (which it does after time), the dessicant will have absorbed as much moisture as it can and now the air in the space has become moisture laden and will condense when cold.

You will need new sealed glass units, but probably not new frames. The UPVC should click out and allow you to change glass.

You can get sealed units yourself at a fraction of the price that a window seller will do them (and new seals as well).

I have just replaced the glass in my two front windows - 1 bay (6 panes) and the double bedroom above it (4 panes). The style was georgian and the rest of the house was plain glass which was how I bought the house. I never liked the georgian windows and always said I wanted to change when I got the chance. We bought the replacement glass from Wincobank Glazing for about £250 and it's K Glass.

Cheers for the advice people!

Most helpful.