[Jar944_2]

It depends on the depth of the extension.
Flush to the outside would be normal with the extension on the inside but if the wall is 8" thick the door may not open all the way, if that matter.

Change to a out swing and that 8" thick wall doesn't interfere anymore.

 

[Jar944_2]

I asked my door manufacturer (ThermaTru) about this and they said the jamb extensions should always go on the exterior side by removing the brickmold. They say it should be used with a sill extender. I recommend asking the manufacturer of your door too.

Depends on the wall. It doesn't work great on a 12"+ thick wall.