You can't do a renovation change on part of a wall (i.e just the external skin).
So you either need to do as you have suggested and model 2 separate walls, and deal with adding empty openings in the second wall and matching them with the windows.
Or you simply apply the reno status to the entire wall and replace the whole wall.
I know that is not how it is done in real life, but until Archicad gives us the ability to renovate just one skin of a wall, that is what we must do.
Another option might be to use a wall accessory for the cladding on the wall.
That will be a separate object but will read the opening information from the associated wall.
Then maybe you can renovate the accessory (cladding).
Of course this will depend what wall accessories you have - if any.
Barry.
One of the forum moderators.
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