25year old attached wash house converted into a room(no building regs)

Might find insulation and ventilation required to comply to change of use difficult to advise unseen

Its important to understand the clear distinction between planning permission and building regulations. Planning permission primarily centres around external aspects of property use and appearance, as well as land use considerations. In contrast, building regulations take a deep dive into the structural and safety aspects, including the internal alterations as in your case. In terms of planning you should be fine but I’d encourage you to ensure your renovation project remains compliant with all safety requirements.

The first thing you need to do is to check with the council if this can be done or if you need any sort of building permission. These days the council may need all sorts of items carried out. Your best bet is to get a structure engineer for whom you need to put the steel in to open up for a new doorway. The other person you need is a an architect who will draw up plans of what is needed in conjunction to all of the works, like, plumbing, electrics, flooring, walls, and ceiling works. These works need to be looked at and passed by the council for you to live in. Once all have been done then you will get a pass letter from the council. You may also have to inform your house insurance company of the works but again have a word with them. Good luck.

Yes you will need building regulations approval to create new door opening.