Hiya ! It is my first post so please understand any mistakes. So, trying to install a new loft ladder with hatch using an old very very tiny hatch (enlarging it). New loft ladder frame size is 1180mm x 680mm and unfrotunately it has to be installed perpendicularly (not sure if the right word). You can see what I mean on attached pictures. After checking everything and planning which joists I have to cut I met a problem which is: Distance between 5 joists (including 3 I have to cut) is 1570mm but the frame is only 1180mm so we have about 390mm empty space which I'm not reallt sure how to fill or how to exactly and safely fix the frame to the existing joists. Unfortunately I cannot fit new frame between 4 joists as the distance is not long enough. I know as well I have to support all the joists around the new entrance. All doesn't let me sleep tidy is how I should fix the frame properly and how to fill the gaps between joists and frame. Thank you for any help and advices. If need any pictures just let me know.