I asked my builder to build my house exterior walls with 7.5 Q-Con and interior with red bricks. He previously built an entire development of homes using Q-Con and mentioned that they had some issues with paint staying on and he doesn't like Q-Con so much. I think the issues were water penetration issues effecting the paint on exterior bathroom walls.

He has agreed to build my house with Q-Con but we seem to have a misunderstanding. He has begun using red brick for all interior walls and for the bathroom exterior walls and Q-Con for all other exterior walls.

He really believes I will have fewer problems with the bathroom exterior walls if they are made of red brick but will replace them with Q-Con now if I request it since he has only done one so far.

The three bathroom walls are not really a huge area of exterior wall space so I don't think it would be a big issue concerning the insulation of the house .....but I'm not sure.

I've read conflicting reports online about some people having the type of water penetration problems in bathrooms that the builder is describing so I believe it to be real but I am not sure if it's because of improper treatment/rendering of the walls. Or maybe the walls were not tiled and grouted properly?

I'd like to hear some suggestions?

Thanks

Mike

In my my current build, all walls are single-layer Q-Con except the bathrooms, which are red brick. I think the problem is that Q-Con doesn't fare well in wet environments.

The term 'damp proof course' comes to mind.

Q-con does have sponge-like properties.

Local contractors put 2-3 courses of red bricks at floor level in wet rooms, higher up the tiles should stop the wet getting to the Q-con.

I've found a Mortar additive called Sika Latex that I believe when added to the mortar for the rendered walls inside and out of the bathroom exterior walls should help reduce water migration.