1. Chapter 27 Insulating Structures

2. Objectives After reading the chapter and reviewing the materials presented the students will be able to: List the ways heat can move through a wall or ceiling Describe the purpose of insulation in buildings Explain how sound travels through a structure Describe safety precautions that should be taken when installing insulation

3. Introduction Insulation: Material that isolates heat and sound from being transferred. Insulation reduces heat loss in cold weather. Insulation conserves cool air in cold weather. Insulation absorbs sound. Insulation retards burning.

4. Heat Transfer Heat moves from warm matter to cool matter. Conduction is the transfer of heat through materials. Convection is the transfer of heat as a result of natural air movement. Hot air rises. Radiation is the transfer of heat by waves, such as those given off by the sun.

5. Reducing Heat Transfer Insulation is used to reduce heat transfer. It holds the heat in the winter and keeps it out in the summer. Wood framing resists conduction better than metal. Without insulation, convection currents will be created inside the stud cavities and the attic space causing heat transfer. Resistivity: is the resistance of material to conducting heat. R-value: Number that represents how well a material resists heat movement. The better it insulates, the higher the R value. Infiltration: airflow that causes heat transfer. Can be through gaps and cracks in the building.

6. Thermal Insulation Materials Fiberglass insulation: Glass spun into fine fibers and formed into a loose mat. Rigid insulation: Insulation made of plant materials or foam plastic in 4’ x 8’ sheets. Blanket insulation: Insulation materials consisting of fibers that matches stud spacing. Loose fill: Loose fiber that is poured or blown by machines into place. Reflective insulation: Insulation that has a foil surface that stops heat waves by reflecting them away. The foil is installed facing the outside of the building. Weather stripping: Material placed around the edges of doors and windows to reduce infiltration. Sealant: Material used on walls to make joints watertight or to fill cracks to improve appearance.

7. Vapor Barriers The amount of water vapor in the air is called relative humidity. Vapor barrier: A plastic sheet or aluminum foil placed under the wall or ceiling covering to prevent moisture in the air from entering the insulation. Aluminum paint may also serve as a vapor barrier.

8. Installing Thermal Insulation Loose insulation comes in bags and is poured or blown into attics and wall spaces. Poured insulation is placed by hand and distributed uniformly over joists using a rake. Loose plastic beads and vermiculite insulation are mixed with concrete. They are poured on to roof decks to insulate ceilings. Rigid insulation is nailed or glued in place.

9. Sound Insulation Sound: Vibration that moves through air and can be heard by the human ear. Sound transmission: The passage of sound through barriers such as walls, floors, or ceilings. Sound deadening materials: Materials that absorb sound. Staggered stud construction: Building technique that uses two sets of studs. The studs vibrate without transferring sound through the framing to the opposite wall surface. Blanket installation is installed the same way for sound as it is for thermal insulation.

10. Safety Insulation can cause sickness or itchiness. Proper work clothes can prevent most problems. Long sleeved shirts, gloves, and loose fitting clothes keep the insulation off your skin. Goggles and respirators protect the nose, mouth, eyes, and lungs. Shower with soap and water after working with insulation. Wash work clothes separately form other clothes. Rinse the washer before using it again.

11. Summary Insulation: Material that isolates heat and sound from being transferred. Conduction is the transfer of heat through materials. Convection is the transfer of heat as a result of natural air movement. Radiation is the transfer of heat by waves, such as those given off by the sun. Resistivity: is the resistance of material to conducting heat. R-value: Number that represents how well a material resists heat movement. The better it insulates, the higher the R value. Fiberglass insulation: Glass spun into fine fibers and formed into a loose mat. Rigid insulation: Insulation made of plant materials or foam plastic in 4’ x 8’ sheets. Loose fill: Loose fiber that is poured or blown by machines into place. Reflective insulation: Insulation that has a foil surface that stops heat waves by reflecting them away. Weather stripping: Material placed around the edges of doors and windows to reduce infiltration. Sealant: Material used on walls to make joints watertight or to fill cracks to improve appearance. Vapor barrier: A plastic sheet or aluminum foil placed under the wall or ceiling covering to prevent moisture in the air from entering the insulation. Sound: Vibration that moves through air and can be heard by the human ear. Sound transmission: The passage of sound through barriers such as walls, floors, or ceilings. Sound deadening materials: Materials that absorb sound. Insulation can cause sickness or itchiness. Proper work clothes can prevent most problems. Goggles and respirators protect the nose, mouth, eyes, and lungs.

12. Home Work 1. What is insulation? 2. What is the R-value?