Keeping the heat in -- but not moisture
Q. We have too much dampness inside our single-story house. A dehumidifier and attic fan run constantly. The walls are insulated with a vapor barrier inside. The ceiling is insulated with two layers of rock wool, with a vapor barrier in between as well as underneath. We limit the length of showers and steam from cooking. Any suggestions? Mrs. Hugh J. Parkhurst Hamden, Conn.
A. These days of energy-saving efforts by homeowners sometimes result in counterproduction, as in your case, of a home that is so weather-tight that inside humidity cannot leak out.
In other words, one problem was solved (insulation to reduce heating costs), but another one was caused (moisture.)
Discuss the problem with a local veteran insulation contractor or the city building department. Our information is that it is a no-no to have a vapor barrier on both sides of the insulation and can only contribute to an increase of humidity inside the dwelling.
For moisture control on the insides of the windows, buy a kit such as that made by Plaskolite Inc., PO Box 1497, Columbus, Ohio 43216, or its equal. Install the window covering per the manufacturer's instructions.
The attic fan and dehumidifier are effective humidity reducers. But you may need to supplement them with mechanical exhaust fans in the kitchen, bath, and laundry. Use the fans to eliminate steam and water vapor promptly.
Weather permitting, allow cross-ventilation where and as practical.
Inspect exterior moisture sources for elimination or minimization. Compel rainwater from downspouts to run away from the foundation of the house.Cock or replace roof and chimney flashing to ensure weather tightness.
Make sure that the ground all around the house slopes away from, not toward, the house.
These recommendations, added to any practical steps already taken, should res ult in a tolerable humidity level inside the house.