Condensation Buildup - Basement

Discussion in 'Remodel Forum & Blog' started by ManCave, Jan 6, 2014.

  1. ManCave

    ManCave New Member

    Messages:
    11
    Location:
    Columbus, OH
    I am slowly finishing my basement and while working on it the last few days I noticed condensation building up on the gas line and the PVC intake pipe for the furnace. There is enough there that it is dripping on the floor pretty regularly. Tonight I also noticed the main electrical line entering the house has some condensation building up on it also. I'm a little concerned... At this point I don't know if this happens all winter and I've just never noticed it before. Or if this is happening because it's just REALLY cold here in central Ohio right now. What should I do?

    I should note that while finishing the basement I put 2" of XPS insulation in the rim joist bays around the entire basement. I also have 1.5" EPS insulation on the walls in all the areas that I am finishing (the EPS ends right near where all of this condensation build up is starting. I don't have drywall up yet so the basement is still all wide open.

    Any help would be GREATLY appreciated!

    Thanks!
  2. Reach4

    Reach4 Well-Known Member

    Messages:
    2,419
    Location:
    IL
    It's because of the cold, but it will be cold other times. Insulating the pipes adequately should solve this.
  3. Dana

    Dana In the trades

    Messages:
    2,922
    Location:
    01609
    Reach4 tells it true!

    Normal wintertime indoor air runs 25-35% relative humidity at 70F, which means it has a dew point between 33-41F. The furnace intake has been pulling in air much colder than 33-41F, and the gas line is very conductive, and exposed to much colder outdoor air. When the pipe/duct is at a temp below the dew point of interior air voila', you get condensation.

    I'm not sure if it's safe or legal to insulate the gas pipe, but you can insulate the air-duct. It doesn't take much- R2 will do, but it's best if it is air-impermeable (foam). If you just did a cheap fiberglass wrap you'd end up with just as much condensation, but it would be dripping through the soggy fiberglass.
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