I need to add an extra internal layer to the outer walls of a project that i'm working on - the layer is shown in aqua colour in the attached screenshot.
When I add the new layer (in this case it's moisture resistant plasterboard for a bathroom) it moves the entire outer wall layer further outwards which makes the wall appear out of line as shown in the screenshot.
How can I add the extra layer without causing the original wall layers to move outwards? Everything should remain in line (the grey thick stone wall) and the aqua layer should be added to the internal side without anything moving outwards.
I'm using Chief Architect Premier X13.
Thanks in advance,