"tzd3sw" wrote in message
om...
I'm building a thermalite wall between my garage and what will be a
utility room. This wall will have a door through. What size gap should
I leave for the door and frame ? Is there a standard size ? This will
be a firedoor if it makes any difference.

Standard door widths, 762mm or 838mm. Add 3mm gap + 32mm lining + 5mm tolerance
on each side, so opening in blockwork = 80mm larger than door.
Standard door height = 1981mm. Add 3mm gap + 32mm lining + 5mm tolerance, so
height of opening under lintel needs to be 2021mm above finished floor level.
You could allow a bit extra for carpets etc, or trim the door to clear them
later.

Peter