Thermal Bridging - A Sign of More Serious Problems
Thermal bridging occurs in one of two conditions:
1) There is not adequate insulate in the walls or ceilings so the cool air and warm air are meeting on the surface causing condensation issues.
2) The house is sealed too tightly, insulated improperly and the thermal bridge is occurring on the plastic vapor barrier on both sides.
The later is more likely than the first condition. Moisture stains appear where the studs are because that is what the water molecules cling to. They drip down plastic and, at least partially, absorb into wood creating a holding point from moisture and eventually staining along the studs.
All of the things to the right may cause condensation issues in any season. Generally, speaking, however, winter moisture means a tight home, with improper insulation methods. Fiberglass batts are NOT an insulator. They form air pockets that air insulators trapping warm air. There is a small problem. On days like today when the temperature is zero outside, the fiberglass is going to get cold too because it is made out of spun glass. Cold material will not trap warm air, it will draw the warm air to it and form condensation. The only reason to have a vapor barrier like plastic is because of condensation. If it happens on your windows, it will happen in your walls too.
Other issue in the winter cause moisture issues such as cloths dryers, showers, baths, dishwashers and stoves. If you have specialty equipment in your home such as an air recovery unit (ARV) it should be checked for proper operation every year. This will help keep your home dry.
Moisture is a huge issue and should be taken seriously. If you have a musty smell in your home but can't figure out where the issue is, call an energy consultant. They will go through the house with you to find the answers you are looking for. This will be a topic I get very in depth with in a later article.