we want to do the flooring in a 10 x 20 area of our basement. we've sealed the walls and put in a hydraulic cement joint between walls and floor and doubled the drainage capacity of the system around the foundation and on the site. We never get pools of water or leaks any more. It's been years like this. But with days and days of hard rain (2inches or more a day) we might get a sheen of wet on the floor. Today after 2-3 days of rain, it is dry, no sheen, and 67% humidity, 45 degrees outside, 65 degrees in the room. We have damped the vents so as not to heat the room fully as yet. Upstairs is 70 degrees. It's a daylight basement room with huge 6 foot wide french doors looking north under a deck, looking into a valley. No sun pours into this room. We have not installed the dehumidifier planned for the area when the floors go in place. We've looked at Mar 2005 fine homebuilding recommendation for subflooring and we've looked at building sciences Healthy Homes subflooring methods. We like the building science one with the dimpled plastic on the concrete, then the eps foam, then the plywood, then the finished floor. If we build this floor with the ability to blow air underneath it when we think there's been a lot of rain, do you think we can keep mold from forming under the floor or in the room? Science reports say mold grows at 60% humidity, and 50-90 degrees, ph 3-8. But some building reports say, don't put in a floor unless you have 50% humidity or less. How much dehumidfier electricity are we going to be laying out to keep this room mold free? Do we have to go to 50% or 60%? Thanks for your help.

I am building a couple interior walls in my already finished basement. It has carpet already- do I need to cut the carpet where the bottom plate will be? (the carper is quite thin) I am also looking at ideas on how to attach the bottom plate- I am thinking about using concrete achors through the carpet? Any suggestions?