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