Warm air + cold surface = condensation.
Condensation in an enclosed environment doesn't dry and = mold.
Condensation in an enclosed environment doesn't dry and = mold.
Warm air + cold surface = condensation.
Condensation in an enclosed environment doesn't dry and = mold.
Usually the boiler room will be well heated by the heat lost from the boiler and any areas of uninsulated wall will warm enough on the surface to avoid any condensation.
However, when sealing off a room you must consider how any moisture that gets in will get out. If the boiler is drawing combustion air from that room and there is an outside source to replace that air, yes it will get cold in there, but when the boiler cycles off the temp will rise.
As for that room contributing to cooling of the basement, yes, unless you insulate the interior walls.
Bud
Interior walls should not present a moisture problem unless you turn that utility room into a second refrigerator. I had a 12' x 16' utility room with a big boiler and a big intake fan controlled by the boiler. I was worried that the room would freeze, but it remained reasonable even during very cold temps. Drywall the side you want to look good and optional on the other side. IMO
Bud
Specific to this - the answer is no. Because if the rim joist is exposed to the interior, it's surface will mostly remain warm (above the dew point) and it will have air circulation to dry if any condensation does develop.Based on the info above, would this mean that if someone insulated their basement fully, but forgot to insulated one small section of the rim joist, then that uninsulated section would get moldy?
You might be right on overkill & overthinking, Bud. I'm picturing this in my basement, where if I had a room on an outside wall that was not insulated, it would be cold; probably a 50+ degree delta temp.Hi Nick, not to get picky, but I just don't see the condensation issue. The room will be cool, not cold and it will be due to venting cold dry outside air. As that air warms up, its RH will go down.
As for warm inside air depositing moisture on the walls inside that room, those walls won't remain cool long enough to form condensation.
As for a vapor barrier, way overkill and technically, moisture moves from high concentrations to low concentrations, not warm to cold.
This is a simple issue and does not need a complex solution.
Bud
Interesting. I've never heard of kraft paper as a vapour barrier - only poly. Must be regional differences. I agree that un-covered insulation is a bad idea. I would only insulate interior walls for sound.If you insulate the interior wall, you should drywall & paint both sides & install a vapor retarder (kraft paper) to the warm side. This will limit vapor migration inside the wall, which will go from warm to cold.
Kraft paper is considered a "Vapor Retarder". Poly is pretty well impermeable, but kraft paper is designed to slow, but not stop vapor migration. Benefit being that, theoretically, water inside the wall structure could eventually dry through the retarder.
Interesting. I've never heard of kraft paper as a vapour barrier - only poly. Must be regional differences. I agree that un-covered insulation is a bad idea. I would only insulate interior walls for sound.