Upvote:1
1 hour 15 minutes should be more than enough to transfer between two non-schengen flights at Frankfurt Airport.
If you are travelling on one ticket, your luggage will be checked through and arriving from Birmingham (usually terminal 1A) and departing to Torono (usually terminal 1B), you can stay air-side and will not have to pass immigration or additional security checks.
Even check-in and bag-drop for new passengers do not close until 40 minutes before departure for the Lufthansa flight to Toronto.
Upvote:3
Yikes, this is tight. Apparently LH thinks they can do it otherwise they wouldn't have sold you the ticket and if you miss the flight Toronto they will rebook you on the next for free and may even put you up in a hotel overnight, if needed.
Terminal 1 has 4 "piers" what are essentially individual terminals by themselves. A, B, C & Z. Some of these are really far apart and not all allow airside connection.
UK is not Shengen so you may be lucky and get all your Canadian entry checks in Birmingham and can do an airside transfer in FRA. I would call LH and ask for gate info and ask whether this will be an airside transfer. If you have to go through security and passport, this seems extremely tight.