Is it possible to run new joist the same way as existing joists when lowering a ceiling
Due it being in such poor condition and not wanting to drop lathe and plaster due to the mess it would create I want to just lower it as height is not an issue.
The room size is 3.65m X 3m and the loft joists run along the 3m currently. I would normally run joists 90 degrees to this however my local wood yard has 3m lengths 4x2 then it jumps to 4.8m which is almost double in price.
Cost is not the main issue because yes of course I want it right, just wondering if I can use 3m lengths instead

Plan is 4x2 screwed to wall around perimeter then span at 400mm centres for 8x4 plasterboard 12.5mm to be screwed and skimmed

Thanks in anticipation

you dont need a dropped ceiling,you can level off the insitu ceiling by using random lengths of one by stuff and packing it out equal flat. you screw the 1x through the laths and plaster into the ceiling joists.
stretching level string lines from diagonal corners of the ceiling will give you a benchmark to work to. use a cheap line level

Anythings possible . I've used shorter timbers before now rather than buy extra. For example you could still go at 90* using the shorter lengths. Once you have put your perimeter timbers in could run one as a trimmer to take the ends of the 3m lengths ( or perhaps shorter) leaving a row of small joists.