Sealant underneath external sill ?

[Coniferman]

I was just examining my old upvc double glazed windows, one in particular which seems a bit cold. Anyway I noticed that there is no sealant underneath the external sill, where it meets the brick. Is there supposed to be any? I guess water is unlikely to be a problem and certainly no problems encountered but is it worth sealing it for extra heat insulation?

 

[Richard C]

Yes even if only to keep undesirable insects out; it probably won’t make much difference to the thermal insulation though! Have you checked that the window gasket is sealing properly?

 

[Coniferman]

ok Thanks for the reply. Will seal it up anyway. I had already replaced the gasket - although only one of the two. You know where there is one on the frame and another on the window that meats the external face of the frame, if that makes sense. I guess if one needed replacing, its worth doing the other???

With the cold window, I decided to remove the trim that had been fitted between the internal sill and the upvc frame. I had wondered if there was some sort of void that could have done with being filled. There wasn't however I noticed a small hole in the paster leading to the wall cavity that was not visible because of the trim. It felt like cold air was coming through this and the trim was not previously tight to the wall. Needless to say I have filled it all up and refitted the trim (after a well needed clean) It does APPEAR to have improved things.