New windows and cavity closure

30 Dec 2023
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United Kingdom
We have recently had old UPVC French doors removed and replaced with Aluminium (fairly high spec) doors.

The old frames were super thick and crossed the cavity, and presumably sealed the cavity along the 4 sides. The new installation being much thinner sits at the outer brick, and there seems to be a gap between the breeze block and the frame. When windy, I can hear air rushing under the frame. There does not seem to be obvious external leak in the silicone. I am reading 5 degrees on the internal frame, when 1-2 degrees outside, which can't be normal!! The internal has been sealed with a wooden trim , which had draught leaking under it, now sealed with a bead of caulk. I am concerned that outside airflow only has 1mm of caulk / silicone separating the cavity from the room.
I would have thought that this type of install is quite common, and if I had done the install would have closed the cavity with expanding foam a few inches back from the opening before putting a new frame in. Am I missing something? Grateful for thoughts.
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