Wooden window, need subframe?

[Loofah]

I was going to be closing up the garage doors with a timber clad frame but am now considering a single skin rendered blockwork wall with window instead.

Would the wooden window frame require a subframe to be set in or am I OK to create the correct size hole while constructing to sit the frame into directly? (+5mm all round for expansion). Seems like it should be obvious but I'd like to check.

The window will be directly underneath the existing solid wooden lintel of the current garage doors

 

[s60tsy]

some old ali windows had a wooden subframe but wooden windows dont need one, would a upvc one not be better

 

[Loofah]

Quite possibly better but not free lol I got a good hardwood frame gratis

I'll get on with the planning, thanks