Roof changes

[regnovice]

My home has poor insulation in the roof. The only way to really improve this without reducing the habitable area is to take the roof off and replace it, boarding the sloping parts above the bedroom ceiling and some otherwise inaccessible areas. Ideally this would be a warm roof but that would raise the roof height so need planning permission and cost a lot.

i'd prefer to put 50mm insulation down the sloping parts, and some sort of insulation board/ roll in the parts that are otherwise inaccessible. I think a warm roof is not required if I can show I cant recover the cost in 15 years.

What's the best professional to advise me on this/ draw up the drawings I'll need for building reg approval.

Hard to picture in my mind but you should likely be able to insulate without removing the roof.
Celotex or similar insulation panels fitted between the rafters usually do the job but beware it can get hot in summer so maybe include a couple of Velux windows.

We need a couple of pictures of what you mean. Pulling down the ceilings and putting up insulated plaster board only loses about 65mm in height.

Not great at diagrams, but I'll try. I just want advice on what type of professional to get advice. The roof looks a bit like this although the top bit is pointed, not flat. The gap between the ceiling and the roof is just 100mm with no insulation on the sloping parts and no insulation on parts of the walls. . Dont want to lose 65mm as the rooms are not big and as the walls are not insulated everywhere it would mean 65mm on 3 walls. This is not a loft conversion as it was built this way.

My in-laws have something similar. Heat loss feels instant in the winter.
You need a reputable roofing/insulation company.
I think a warm roof may be a bit too expensive, and anyway the ventilation requirement would detract greatly or even completely. You will need some very efficient 50/60mm to insert between the ceiling and the roof, to keep the ventilation. There will be products available.