Expert: Dan Griffin - 12/23/2008

Question
Hello -

I am in the process of finishing my basement in the Northeast. Our watertable is a bit high. We have french drains and sump pump with backup. I have waterproofed the poured concrete walls with extreme drylock. I plan to put an additional sump pump just to be safe even though we have not had water come through the floor.

Given that we may run into humidity moisture issues - I am planning to use steel studs. My question relates to the type of insulation and drywall I should use. I would like to avoid mold issues especially since humidity and little water seepage is possible. I have heard that fiberglass insulation is not good from the mould point of view. I was also told to consider the styrofoam type of board for insulation. One opinion had me glue it to the wall. My concern is that even though the water may sit with heat and humidity and catch mold. I am not sure if this board can be put on steel studs so that I can keep a air gap between the concrete walls and the studs/insulation. What would be your recommendation with this situation. Should I use board insulation or poly-encapsulated fibreglass? Should I glue it directly to the concrete wall or put it on the studs?

Also, what type of drywall board you would recommend?

Thanks in advance

Answer
Al,  I'm a belt and suspenders type of guy.  If you really expect moisture trouble, I would use 1 1/2" metal studs set on treated 2x blocks so water can get out from behind the wall and some air can circulate.  I would hang visqueen against the concrete wall.  I would be tempted to not use insulation, but I don't know your location or climate.  You could use rigid on the face of the concrete with joints taped or sealed.  Your local code official may have energy requirements that must be met.
There are mildew proof drywalls.  
http://www.gp.com/build/product.aspx?pid=4659

This is a good article on the issues:
hwww.state.mn.us/mn/externalDocs/Commerce/Basements_110602012856_Basement.pdf -