Insulate attic apartment to keep cool in summer

How do I insulate my attic apartment so that I don't have so much heat inside in the summer?

Does anyone have tips?

I will soon insulate the roof from the inside, remove the old 80s insulation that still has an aluminum foil layer.

Best regards M Michael

Hello, have you installed an underlay membrane under the tiles? That would be very important, and how thick are the rafters? I have installed WLG032 for the insulation between the rafters, and what is at least just as important is the vapor barrier. Also, with roof windows, there are big differences in the glass; some keep the heat out and the cheaper ones do not, but I don't know the exact designations now.

Regards abo68