The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
First Aid For The Ailing Houses
An attic, especially under a dark roof, becomes heated through the open exposure of the roof to radiant heat from the sun. If the attic is not ventilated, the still air confined within it may become much hotter than the outdoor air. For an example, on a day when the outdoor air was at 95 degrees, the air in an enclosed attic was found to be 141 degrees. The chief reason for discomfort on summer days and nights is lack of ventilation in the attic. The hot attic air heats the attic floor and the ceilings of the rooms below. The hot ceilings radiate heat to everything within the rooms. At sundown, the attic air begins to cool off; but it may be many hours before it drops to a temperature at which the ceilings cease to be radiators. During all of the hours when the attic air is overheated, the effect on the house is that of a hot-water bottle. Attic floor insulation of the usual forms will have no effect, for in time it, too, will become heated.
The situation can be greatly relieved by providing attic ventilation. This may be done by placing louvers (protected openings) at the proper spots to create a natural circulation of air. Air will rise when heated, and cool air will replace it. Louvers placed under the eaves will permit cool air to enter the attic space, while louvers placed high in the gables will permit the hot air to flow outside. If the house has a hip roof (with no gable ends) a vent must be placed at the highest point on the roof to permit the passage of the hot air.
One excellent plan is to provide a scuttle at a high point in the roof; for convenience, it can be arranged to open and shut with cords and pulleys. Beneath it there should be a trap door in the floor of the attic, preferably opening into a hall or other central location. As it is heated, attic air will rise through the open scuttle. This will draw air through the open trap door, to be replaced by air entering through open windows. Through the circulation thus set up, no air in a house should rise to a temperature higher than that outdoors.
Attic fans provide ventilation not only for the attic itself, but will also cool the rest of the house by creating a forced flow of air from the lower areas to the attic, thus carrying out the hot air by its natural path, There are two types of attic fans. The first is installed simply to keep the attic itself cool and is usually placed in one gable opening, exhausting air drawn in under the eaves or from the other gable. For extreme summer temperatures, the attic fan should exhaust the air once every minute. Air-inlet space should be figured by the same ratio as for kitchen exhaust fans (see section on Kitchen Fans).
