We are in the process of replacing the paneling in our modular home with gyproc. Should we remove the paneling on all walls or is it all right to leave it on the interior walls and just cover it with gyproc?

Fortunately, there is no need to go to the extra work, mess and expense of removing the wood veneer paneling on either the interior or exterior walls. Just remove all the window, door and corner moldings first. This is also a great opportunity to upgrade your vapour barrier on the exterior walls. Often, homes built before 1982 came equipped with 2 or 4 mil vapour barrier that was poorly installed and poorly sealed. These leaky vapour barriers permit moist air to condense in the wall and ceiling cavities, creating opportunities for mould and rot. So installing a 6 mil UV rated poly vapour barrier against your exterior walls before you install new gyproc will help seal the exterior wall cavities. Also consider installing a dehumidistat, inter-connected to your bathroom fan to evacuate any build-up of moist air in your home.

You will also need to consider how you are going to deal with or treat the window and door frames because the additional layer of gypsum will add about 5/8 inch thickness to your walls. One option is to overlap the existing window and door frames with gypsum but hold back 3/8 inch all around (this hold–back is called a “reveal”). Then cap the gypsum edges with “J” mold and finish with mudding, sanding and painting. The advantage of this strategy is that you avoid having to build out your window and doorframes and you don’t have to install new window and door trim moldings.