Best method I find for draftproofing is, 5mm gap around edge roughly to allow for expansion and contraction, expanding foam around the 3 edges in the 5mm gap.. then silicone sealant over the top on outside, caulking on inside.
then you have not only a thermal separation between the window frame and wall, which means less heat transfer from frame to wall which in turn reduces heat loss anyway and with foam doesnt absorb heat which is another added insulation factor as theres no heat transfer through the foam from the frame to the brickwork.
and with silicone on outside, foam between, then caulking on inside you have 3 layers of draftproofing.
I also use cavity closers on cavity gaps, which removes any cavity drafts also and provides a DPC.
never had a draft on any of the windows fitted, and council always seem impressed at the high standard of installation.
in my oppinion all installations should be done like that... but more often than not, no foam is used around the window and gap is just covered with caulking / silicone. then when the sealant breaks down on the outside a draft occurs.
or if not that the windows are fitted tight against the brickwork.. then the brickwork soaks up all the heat from the frame, which then absorbs more heat from the room.
So much for fensa, lol I saw a door fitted by a fensa registered company and they not only put silicone accross the drains sealing them off but left with daylight visible through the gap between the metal door and frame.