The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
First Aid For The Ailing Houses
Another form of insulation is puffed mica, in pellets of gold color. Being dry, the pellets can be poured into place and are suitable for a filling between attic floor beams. The depth of the filling should be 3 to 4 inches. The pellets are noninflammable and water resistant.
Sawdust, straw, hay, and similar materials should never be used, for they are inflamable, absorb and hold moisture, and form breeding places for a variety of insects as well as mice and rats.
No material should be used that attracts vermin, either as food or as a nesting place. It is, of course, preferable to use a material that is fireproof or at least slow burning.
Metal-foil Insulation The passage of heat through a surface can be largely checked by reflecting the heat waves, much as a mirror reflects light. The effect is explained in the section on Radiators. The principle can be applied to house insulation through the use of aluminum foil. In application, one or both sides of the foil should face open air. Two sheets of foil are placed between adjoining rafters or studs. They are not drawn tightly, but slightly crumpled to form an air space between. Some brands are accordion-pleated to emphasize this effect. Interior heat is reflected back into the house, and exterior heat is prevented from entering. Installation begins with lining the spaces with airtight and waterproof paper. In a roof, similar paper is stretched on the exposed edges of the rafters. In a vertical wall, the inside wall covering takes the place of the second layer of paper. The three spaces of dead air thus formed give insulation in addition to the effect of the foil. Stiff insulating boards with one side covered with foil, and foil on a backing of building felt can be obtained. These should be so placed that the foil side faces in the direction of the heat that is to be reflected, and forms one side of an air space.
Wall and Roof Condensation When insulation of a fibrous nature, such as mineral wool, insulating fiber, stiff insulating boards, etc., is applied to the under side of tight roof sheathing, there may be trouble from condensation, if the house air is humid. These materials can be penetrated by water vapor in the house air, and condensation will occur when the vapor comes into contact with the cold sheathing. Ice may form. With melting, and with water of condensation that does not freeze, the material becomes damp and loses its insulating effect. In extreme cases there can be a drip to the attic floor similar to that from a roof leak.
