Aluminum windows: seal tightness and resolving leak

[Winchy123]

Not quite DIY but would appreciate advice!
We had aluminium windows installed.
1. Seals: I was surprised that they were noisier than the UPVC ones they replaced (and also draughtier than I expected). Looking closely at several of the windows I could easily get a business card between the main frame and opening window. After discussion the installer has suggested putting thicker rubber in. Does this sound sensible?

2. Leak. After heavy rain 2 of the windows let in water where the frame and sill meet. The sales man from the manufacturer visited and said "The leakage appears to be as a result of the frame and cill sitting directly down onto a single skin of brick, which is exposed to the elements outside. There is nothing obviously wrong with the window, so I believe that the leak has been caused by the fabric of the building (i.e. not having the correct D.P.M. installed between the D.P.C. and the floor screed.) not the window."
I'm surprised: windows I've had previously in single skin buildings haven't leaked. Despite not accepting responsibility they propose to install some form of patch.

I'd appreciate views - and/or recommendations of an independent person I could get to look at this (we're in Hampshire)

Thanks

 

[Notch7]

Do you mean the window goes down to the dpc?

If the rain penetration gets in where the frsme and cill meet -thats an installation fault.

Did the previous windows leak there?

New windows should correctly compress seals when the sash is closed and the lock operated. Its either manufacturing fault or lack of adjustment when fitted or fitted twisted.

Sometimes damp issues are caused by the fault of the fitting, but in this case Id say they are avoiding taking responsibility

 

[Gazman16]

photos would help