Exterior Wall Material

[footbridge]

I've added an addition and now one of the exterior walls is partially interior, new roof bisects this wall. What is the best way to keep the exterior portion the same and change only the interior without change the exterior?

[ben.144787]

I would recommend looking at stacked walls. You can make the bottom portion of the wall using your interior wall, and the top with exterior, and if you should change either of those two, the stacked wall will reflect the change.