Replies

1. 
   maine_tyler | Jan 30, 2021 08:36pm | #1

   55 RH is pretty high for winter. At 74 degrees F that's a dewpoint of about 56 degrees F. So in theory any object below that temperature will form condensation.

   What are your sources of moisture? Lots of showering going on perhaps? Tight structure and low levels of ventilation? Bathroom fans, range hoods, etc. being used?

   "had condensation on one wall of cathedral ceiling in living room, the inside wall." What is meant by this? Do you mean the interior of the ceiling has condensation? Is it uniform, in strips, or other?

2. 
   Jtice13 | Jan 30, 2021 10:39pm | #2

   Thanks for your response. Pic shows white ceiling, green is the wall where you can see about 3 lighter spots which were the condensation areas that were dripping. Structure is tight and since my first post I found that the two bath vents were emptying into the attic ! But every window is showing much condensation on inside everyday even if bath vents not being used for a few days. Thanks

   
3. 
   oberon476 | Jan 31, 2021 12:19am | #3

   From University of Minnesota:

   Maximum Recommended Humidity Levels based on engineering studies at 70° F conducted at the University of Minnesota Laboratories.

   • Relative humidity levels above these are not recommended at the low
   outside temperatures indicated, unless special provisions are taken in
   building construction.
   • If higher relative humidity levels are required because of special interior
   environmental conditions, the window manufacturer should be consulted.

   Outside Air Temperature Inside Relative Humidity
   -20° F or Below Not over 15%
   -20° F to -10° F Not over 20%
   -10° F to 0° F Not over 25%
   0° F to 10° F Not over 30%
   10° F to 20° F Not over 35%
   20° F to 40° F Not over 40%