Icicles forming on the outside of the house from stove hood vent-help!

Vic Schapansky
by Vic Schapansky
I have ice forming on the outside wall and vent location. I have insulated the pipe which goes up into the attic and out the side of the house. I have built a stearafoam box where the pipe runs inside and insulated it as best I could.
I live in a cold location so not sure what else to do. Before I did this insulated box I had condensation coming down the pipe into the cupboard.

  3 answers
  • Wendy Wendy on Apr 03, 2018

    You re probably getting back drafting. Where the cold air from outside is travelling in from the exterior vent and mixing with the warm air from the inside your house., the warm and cold causing moisture and then the cold air is SO cold today that it is freezing the condensation that forms. First thing to do is check that the exterior vent outside is closing properly. The flaps on the cheap builders ones can freeze open and it lets the cold air right in.

  • Kelly Kelly on Apr 05, 2018

    If I understood you right, your vent exits through/ near the roof, right? Your vent stack may not be high enough to pull the vented air/ moisture up and away from the house, causing that condensation to come back down. Check the recommendations for vent stack heights and you may be able to just extend your stack (usually above the roof line) and properly draw that up and away.

  • William William on Apr 05, 2018

    I agree with Wendy. The outside vent should have a flapper that opens when the hood is on. It more likely is not closing when the hood is off. If it does not have a flapper then you need to replace the vent with one that has a flapper.