The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

How To Remodel Basements And Attics

Foil insulation is installed as indicated in Part E of Fig. 2. There must be an air space on both sides of the foil. In other words, nothing but the nailing flanges should touch structural details or surface materials.

Fig. 3 shows how an attic floor can be insulated to reduce the transmission of sound through the floor to the rooms below it. You can use either 1/2-in. rigid insulation or thick felt.

CONDENSATION CONTROL

When insulation is used as suggested in Fig. 1, some means of good ventilation for the unused spaces between the knee walls and eaves, and also the space above the ceiling, should be provided in order to prevent condensation (dampness during the winter months). Unless such ventilation is provided, knee walls, dormer walls and ceilings may become damp or actually wet. Parts A, B and C of Fig. 4 show how such ventilation can be provided. As indicated, air must enter through the eave vents and be exhausted through outlets in or near the top of the roof. The total area of all eave vents should be 1 sq. ft. for every 100 sq. ft. of floor area in the attic space.

HEAT-GAIN INSULATION

In climates where the summer sun is exceptionally hot and where attic spaces are likely to be unbearably warm, the use of a particular kind of insulation will be helpful. Suppose, for example, that a roof such as indicated in Part F of Fig. 2 is subjected to exceptionally high heat from the sun. During the day the roof temperature may be as high as 130 degrees. When no roof or ceiling insulation is used, as indicated at X, the roof absorbs great quantities of heat, much of which is radiated to the remodeled attic space. Mass insulations, such as shown at Z, may retard heat flow for a short time, but in doing so they absorb heat which is eventually reflected into the attic space. The radiation process is likely to continue during much of the night. Foil (reflective) insulations, such as shown at Y, have little bulk or mass. Thus, they cannot store much heat or emit appreciable amounts of radiation. In addition, foil insulations tend to reflect the sun's heat away from attic spaces.