Ventilation Tips :

Ample Attic Ventilation:

Winter Frost Damage on Attic Roof Sheathing

The best vented attic will have a continuous ridge vent along the peak. Along the lowest edge of the roof overhang, it will have a continuous soffit vent. Having either one vent or the other alone won't do. Air must come in at the bottom of the roof in order to circulate out at the top. Almost 85% of every attic is improperly vented. *Soffit vents are designed to take in air, roof vents are designed to exit air.

Attic insulation placed correctly:
The insulation between your rafters should stop at the outer edge of the house's outside wall. That way it won't block fresh air from the soffit vents at the low edge of the roof. With blown-in insulation like cellulose, "channel vents", or "baffles", made of plastic foam or cardboard need to be inserted between rafters to keep the loose insulation from falling onto soffit vents. Be sure the insulation hasn't flattened the vents or baffles. Stand in the attic with all lights off. You should be able to see daylight from the soffit vents at the roofs edge. Giving immediate attention to these areas will ensure that your attic is being properly vented, and you can expect to get the full life expectancy out of your building materials.

Bathroom Vents:
Another common, but unsatisfactory practice, allowing heat to enter the attic, involves installing bathroom exhaust vent duct into the soffit vents, rather than correctly installing the duct to an outlet vent. Bathroom exhaust vents should be vented out through the roof with a travel span of no more than 6 feet. Soffit vents are inlet vents, not outlet vents! Everything that exits the house at a soffit vent immediately re-enters the house in the attic space, because that is what soffit vents do, they bring in outside air flow. Not only will this add heat, but it will also add humidity and moisture to the attic, defeating the very reason for installing the bathroom fan in the first place. This is a REAL PROBLEM! Even a home with functional attic ventilation can now develop mold on the roof sheathing cavities above these unsatisfactory ducts. Now you have no air flow, added heat and humidity in a dark, moist environment - THE PERFECT CONDITIONS THAT MOLD NEEDS TO GROW.