I am currently looking at this myself, I have sourced a local company that does a wide range on internal doors up to 2140mm (7ft) doors but I had my external doors and window head heights at 2.2m. My ceiling height is 2.750.
My question is, is it ok to have the internal door head height that bit higher than the window head heights or would I be better lower the window and external height thatch or pay an additional £80 per internal door to raise them to match the 2.2 head height.
I'd like you opinions on this as whilst it's a small thing it's been like a brain work and I can't seem to move on to the other 100 decisions I need to make quick till I land this one.