 Helps to prevent the transfer of heat either into or out of a building  Winter – keep heat in  Summer – keep heat out  Heat is transferred through walls, floors, ceilings, windows, and doors at a rate related to:  Difference in temperature  Resistance to heat flow provided by intervening materials

 Done after exterior of house is completed and house is water proof  After rough plumbing system is installed  After rough electrical system is installed  After rough HVAC system is installed

 Three methods – conduction, convection, radiation  Conduction – transmission of heat from one molecule to another within a material, OR;  From one material to another when they are held in direct contact.  Dense materials such as metal or stone conduct heat more rapidly than porous materials such as wood and fiberglass.

 Convection – transfer of heat by another agent, such as air or water.  In large areas molecules of air can carry heat from warm surfaces to cold surfaces.  When air is heated it becomes lighter and rises.  Air is a good insulator when confined to smaller spaces  Or porous materials and their cells help confine heat

 Heat is transmitted by wave motion in the same manner as light.  Radiant waves do not heat the space through which they move.  But when they contact colder surfaces the energy is absorbed.

 Great insulators include:  Air – already mentioned  Fibrous materials because of the porosity of the fibers  Also because of the thin film of air that surrounds each individual fiber  Good insulation material should be fireproof, vermin proof, moisture proof.

 Loose Fill – Sprayed or poured into cavities that require insulation.  Rigid Insulation – usually used for roof and wall sheathing, subflooring, interior surfaces, base for plaster and synthetic stucco exterior wall finish.  Reflective – usually a metal foil.

 Flexible – blanket, quilt, or batt.  Blanket insulation is enclosed with paper tabs on the sides for attachment.  Made of fiber glass or fiber-like materials  Paper also serves as a vapor barrier.

 Heated areas especially in cold climates.  Walls, ceilings, and floors, crawl spaces, finished attic, finished basements.  Best to have insulation as close to heated area.  For example the ceiling joists should be insulated if the attic is unused. If the attic is used, ceiling joists and rafters should be insulated.

 Insulation and other building materials have an R-Value.  (R) represents resistance, which is the opposite of conductivity or conductance.  The higher the R-Value the better the insulation.  2x4 insulation has an R-Value of 13.  2x6 insulation has an R-Value of 19.  Thicker the insulation the better the R-Value.

 Water vapor is always present in air.  Acts like a gas and penetrates wood, stone, concrete.  Water vapor creates condensation.  When warm air is cooled, some of its moisture will be released as condensation.  Condensation reduces the R-value of insulation.

 Vapor Barrier – Membrane through which water vapor can not readily pass.  Vapor barrier must be installed on the warm side of the insulation (heated side).  Prevents moisture from moving through the insulation to the cool side where it could condense.  If insulation roll does not have a vapor barrier, use polyethylene films or rolls.

 Always wear safety glasses, and vapor mask if applicable.  Don’t rub or scratch your eyes or skin.  Wash hands with cool water and soap. Do not wash with hot water.  Wear loose fitting clothes with long sleeves.  Wear gloves if provided.  Do not play with insulation. No horseplay with insulation.