In the summer of 2004 we built a 780 sf addition on a 1200 sf ranch style house. The existing house has 2×4 framing with fiberglass ins. and the addition has 2×6 framing and we sprayed icynene foam for insulation. The house already had a sealed combustion furnace, but did not have an air to air exchange system.
We had the normal amount of condensation the first heating season. However, on really cold days we would get frost on the windows and especially at the threshold of the patio door that ewe put in the addition.
I was certain that the threshold problem was dew to a metal sill pan that I put under the patio door causing thermal transfer. So we took the door out and modified the sill pan. We also cut 4″ fresh air intake into the retun air duct to the furnace and installed a bath fan connected to a humidistat. The condensation problem continued, but we assumed it was the normal condensation from the construction materials etc.. . This winter the windows are not condensating as badly but there is still frost on the threshold of the door. I have had the Anerson repo out to look at the weather stripping and it all checke dout. I don’t know what to do. Any suggestions would be greatly appreciated.
Replies
Too much humidity in the house? is the humidifier set too high? Do you use your bath and kitchen fans?
My aunt lives in a newer condo and occasionally gets condensation on an exterior wall. She complains to me (like I built it) and I asked her if she uses her bath fans? "Nope, but that cant be it. Something must be wrong with the builder".
Did I mention my family is nuts?
Thank you for the reply, but they are using the fan ( there is only one bathroom on the main floor). The fan has been connnected to a humidistat which is supposed to start the fan when the interior humidity reaches 45%.