Hi folks.
Could anyone afford a definitive answer to our conundrum?

Old garage now habitable space, new garage aded to the front of old
garage with access door between the two spaces.

Is there a definitive door spec. for this connection?
Builders have built standard door opening as per plans but we're now
confused as to whether the door needs to meet thermal requirements of
"part L" i.e. an "external" door due to the garage being uninsulated
rather than an internal fire door without any specific thermal rating?

Cheers
Pete