Software
Houzz Logo Print
epicurus22

Condensation on furnace room ceiling

2 years ago

We have a furnace room in the basement where the ceiling is underside of a landing exposed to outdoors. In winter, when the furnace is running we get heavy condensation on the ceiling due to the heat hitting the cold ceiling. I plan to cover the ceiling with foil/bubble wrap insulation to create a barrier between the warm and cold. Is there a better way to do this? Thank you in advance.

Comments (8)

  • 2 years ago

    Possibly, but you may have a different problem. You may have combustion by-products (CO2 and water vapor) escaping into the room, eg from a cracked heat exchanger. You should probably get it checked out.

  • 2 years ago

    Probably you should have the furnace looked at, and then maybe add some insulation either way. There should be better options than foil and bubblewrap though...

  • 2 years ago
    last modified: 2 years ago

    I'm not a pro, but the foil/bubble wrap sounds vapor impermeable to me. Depending on the material of the ceiling, you may not want it impermeable, unless that ceiling material can vent to the outside (else you could end up with mold, rot, etc). They do make smart vapor barriers that will let humidity move one direction, but not the other, and that may end up being part of your insulating assembly. Certainteed membrain is one example. There's a lot more to the eye about insulating in that type of a situation than meets the eye (to prevent other issues). After you get the furnace checked out, consider finding an insulating contactor who really understands building science - many don't.


    You may also be able to do some dehumidification of the room.

  • PRO
    2 years ago

    What you need is to get the best local HVAC folks to your site. ASAP

  • 2 years ago

    Condensation occurs when warm air comes in contact with a cold surface. One way to prevent this is to cover the ceiling with insulation so that the surface temperature is close to the room temperature. Foil and bubble wrap are poor insulators. An insulation value of R-10 to R-13 should be suffient. I recommend sealing all the joints so the warm air can't get past the insulation barrier.

    The other question is why is the furnace room getting warm and it there a high level of humidity. This is where you need an HVAC pro to do an evalution of the furnace and the ventilation of the room.

  • PRO
    2 years ago

    HVAC pro NOW and yesy ou need to address that part exposed to the outside I cannot figure that part out .All of this area needed to be insulated

  • PRO
    2 years ago

    "In winter, when the furnace is running we get heavy condensation on the ceiling due to the heat hitting the cold ceiling." Warm air contacting the uninsulated ceiling surface may or may not result in condensation forming on the surface. Condensation occurs when the temperature of the surface is at or below the dewpoint temperature of the air. While the condensation could be the result of a leak in the furnace exhaust, it's more likely that the the furnace is heating the space surrounding it and evaporating moisture that is in the surrounding basement walls. It's not clear without more information whether the space needs to be insulated or whether moisture control alone would be more appropriate. If it's not a leak in the furnace exhaust, I suggest you consult with an insulation contractor who understands building science principles.

  • 2 years ago
    last modified: 2 years ago

    In reference to the comments on airsealing - be aware that if there is a flame and it's not sealed combustion, it requires a supply of air for combustion. In years gone by, it was acceptable to source that air through a normally (i.e. not tight) building enclosure and tighter structures required a dedicated means of combustion makeup air. By tightening up the structure, you can potentially change this balance, which could lead to a safety issue - so do ask the HVAC guy about that.