Have you had any builders come round to give you an idea of what is possible? We’re waiting for our loft conversion to start but I got recommendations from friends and friends of friends for builders – had 4 round and all 4 use their own architects which I understand is probably the better way to do things as they’re used to working with each other and knows their style etc.
Now ours is a 1930s semi-detached house which is pretty standard and we have a long landing which makes wrapping a staircase over the top of the existing staircase fairly straightforward. Obviously that’s not so obvious in your case and I doubt there’s a one size fits all way of doing things here. It’s hard to know without knowing the sizes of the rooms, the height of your ceilings, structural walls etc. A few ways spring to mind – one would be to put the staircase to start where the storage cupboard is by bedroom 3 and wrap it round so you lose space where your master bedroom wardrobes currently are – no idea if this would affect the use of the loft space to still give you 2 bedrooms, I guess it depends if getting a toilet or bathroom up there would be useful too? I guess it would be for a 5 bedroom house The second way that occurs to me would be to turn that storage cupboard into a new entrance to the master bedroom and then lose some of the master bedroom to making a little landing, start a staircase to then turn over the existing staircase.
From what I’ve seen the new staircase doesn’t necessarily need to be as wide as the existing staircase but maybe that’s just because our staircase is quite generous – there are obviously minimum sizes to stairs. A 3rd option might be to somehow change the second bedroom to the master bedroom – would obviously make the space tighter but the en suite looks quite large so making that a bit smaller and making the rest of the space a walk in wardrobe type room could be a pay off.
I guess I always find an en suite a bit of a luxury I could (and do) easily live without so a 4th option could be to make the en suite a second bathroom and would make it easier to plonk an additional staircase in. It might also mean that the 2 bedrooms in the dormer might be slightly bigger and they would be able to use the bathroom at the bottom of the stairs.