The artic has sent a cold blast down across a good portion of the country this week. It's gotten so cold I have seen polar bears heading south.
Well, not really, but it's pretty darn cold.
The cold weather has spurred an up tick in calls to my office for thermal imaging scans and energy audits. When the mercury plummet's, the coldest parts of a house become more noticeable. An uncomfortable house is not pleasant.
One of the more crucial parts of a houses thermal envelope is the plane between the house and the attic. Most people call this the ceiling. Approximately 30% of heat loss occurs through the ceiling. Standard building practices make the ceiling holier than the Pope. Wires, pipes, lights and vents are the common and necessary ceiling penetrations. Unfortunately these holes are rarely sealed.
A common cold weather event in an attic is frost forming on the roof sheathing. During a recent energy audit I found an single long, frosty line on the roof sheathing. It was concentrated closest to the soffit vent dissipating up the sheathing. I knew what was causing this long and frosty line of condensed moisture. It was due to another common and wrong building practice, placing the bathroom vent into the soffit.
Soffit vents are the intake part of the attic ventilation system. The exit is the ridge vent. Subsequently the moisture blown out the soffit effectively gets sucked into the attic through the vent. Interestingly building codes state that a vent can not expel within three feet of a building opening. Venting out the soffit is done in my experience regularly on new construction and on renovations.
I think this long and frost line demonstrates exactly why venting out the soffit is not an acceptable means of expelling the warm, moist air from the bathroom.