| Since the energy crisis of the '70's, the climate of our | | | | decking is allowed to overheat... which is just what |
| attics has taken on more importance as we have | | | | happens in an underventilated attic. |
| insulated, weather-stripped and sealed our homes into | | | | In the cooler months, moisture is the most serious |
| virtual mausoleums. The idea of actually allowing a | | | | concern. Even with the use of vapor barriers to keep |
| part of our home to be cold... and to do it | | | | moisture from entering the attic, there are air leaks |
| intentionally... | | | | around ceiling light fixtures, bathroom exhaust fans, |
| can give one the chills! It seems a contradiction to all | | | | access panels and fold-down attic stairways that |
| the brainwashing we have received regarding the | | | | allow unwanted moisture into the attic. Just going into |
| absolute need for an energy efficient home. But your | | | | the attic to bring down that old Monopoly game can |
| attic is unlike other areas of your home, performs | | | | increase the moisture level in the attic a hundred fold. |
| different functions and, to do its job, must be | | | | Moisture condensing on the framing members and |
| allowed to... | | | | the inside of the roof deck can lead to the growth |
| breathe!! Think of your attic as a buffer zone. | | | | of mold, mildew and rot in the roof deck and framing. |
| Outside in the "real world" meet Mother Nature in all | | | | And for those of you who use the attic area for |
| her glory, with temperature swings and moody | | | | storage, watch those roofing nails and any metal |
| weather. Inside your home, you have relatively | | | | reinforcements! Have you ever noticed that items in |
| constant temperature and humidity hopefully | | | | the attic seem to have evidence of slight water |
| matching the health needs of the folks inside. The | | | | drips, but there doesn't seem to be a roof leak? |
| attic allows for a transition between the wild and the | | | | Glance at the business end of the roof nails sticking |
| wonderful through the cooperation of your roof, | | | | through the roof deck. Are they rusty... or is the |
| insulation, vapor barriers and ventilation. | | | | wood around them stained? If so, you almost |
| The attic roof, of course, keeps rain and melting | | | | definitely have an attic moisture problem. Moisture |
| snow from ruining your Persian carpets. | | | | from the living area is entering the attic and freezing |
| Insulation in the attic slows down the movement of | | | | on the nails. When the attic warms slightly, the ice |
| heat up from your living space, trying its darndest to | | | | melts and drips onto your stuff. |
| keep the inside of your home warm or cool | | | | Mystery solved! As if that wasn't enough, relative |
| regardless of the attic temperature. | | | | warm and cold spots on the inside of the roof deck |
| Vapor barriers in the attic keep moisture rising from | | | | can lead to the nightmare of ice dams and their |
| your living space away from the insulation. They are | | | | associated roof leaks when the roof is snow-covered |
| needed because damp insulation loses much of its | | | | (see article on ice dams for more information). |
| value. Vapor barriers can take the form of plastic | | | | Understanding non-mechanical attic venting... |
| sheets installed on the attic floor (under the | | | | One common type of vent, especially in homes built |
| insulation), a built-in paper or aluminum foil facing on | | | | prior to 1980, is the gable vent, which is a louvered |
| the insulation itself (always installed towards the living | | | | and screened vent located at or near the peak in the |
| space), or in the form of special vapor barrier paints | | | | sidewall of the attic. Gable vents come in different |
| (See article on insulation for more information). | | | | sizes, materials, and shapes... triangular, rectangular, |
| Sufficient ventilation helps to keep attic temperature | | | | wood, plastic or metal. They offer a reasonable |
| and moisture at their optimum levels for the season. | | | | amount of ventilation in the upper-most areas of the |
| In winter, the perfect attic temperature is the | | | | attic but they do not produce uniform temperatures |
| outside temperature... cold and dry. | | | | throughout the attic, leading to the formation of "hot |
| In summer, the ideal is to have lots of air movement | | | | spots" of overheated motionless air. |
| so the attic is as cool as possible... without adding | | | | By far the best non-mechanical venting system is the |
| refrigeration! Proper attic ventilation has year-round | | | | combination of soffit vents and ridge vents. This |
| benefits... | | | | type of ventilation requires a specific roof design with |
| The obvious benefit of increased ventilation in the | | | | an overhanging area at the lower edge of the roof |
| warmer months is a lower attic temperature, which | | | | called a soffit. |
| can decrease cooling costs in the home. This is true | | | | Vents are installed into the underside of the soffit |
| regardless of how much insulation there is in the attic. | | | | overhang to allow air to move into the attic. The |
| In fact, attic insulation can actually cause increases in | | | | graphic shows a continuous soffit vent which runs |
| temperature in the home as the insulation holds the | | | | the entire length of the soffit. |
| heat long after the sun is gone, continuing to transfer | | | | To complement the soffit vents, another vent is |
| it slowly through the ceilings into your living space. | | | | installed at the peak of the roof, called a ridge vent. |
| Though we think of attic insulation as a barrier to the | | | | This is a replacement for the uppermost shingles |
| movement of heat, the oppressive heat of an | | | | bridging the peak of the roof, allowing air to flow in |
| underventilated attic can make your insulation a "fair | | | | or out of the attic along the entire peak. The system |
| weather" friend. | | | | is devilishly simple in function yet effective... warm air |
| In the warmer months, a not-so-obvious effect of | | | | in the attic rises and exits through the ridge vents to |
| lower attic temperatures is increased roof shingle life. | | | | be replaced by cooler air entering the soffit vents. |
| Though asphalt shingles are designed to take the | | | | Because the path of the cool air is along the |
| abuse of the sun for many years, they are | | | | underside of the roof deck, it provides uniform air |
| subjected to greater temperatures when the roof | | | | movement and the best possible ventilating action. |