Double, triple sealing.

[Russell griffiths]

Morning all. 

I have been looking at a lot of windows and a fair few have 3 rubber gaskets to seal up when you pull the windows shut. 

Now I know a few of you have gone with rationel  windows, now looking at the website it looks like they only have 2 sealing gaskets, am I looking at the wrong windows. 

Or is this something you have never noticed or am I over thinking it. 

[ProDave]

Yes definitely only 2 seals on my Rationel windows. But they do seem to seal very effectively, no obvious leaks in practice or when doing an air tightness test.