LOCATION OF INSULATIONIn most climates, all walls, ceilings, roofs, andfloors that separate heated spaces from unheated spacesshould be insulated. This reduces heat loss from thestructure during cold weather and minimizes airconditioning during hot weather. The insulation shouldbe placed on all outside walls and in the ceiling. Instructures that have unheated crawl spaces, insulationshould be placed between the floor joists or around thewall perimeter.If a blanket or batt insulation is used, it should bewell supported between joists by slats and a galvanizedwire mesh, or by a rigid board. The vapor barrier shouldbe installed toward the subflooring. Press-fit or frictioninsulations fit tightly between joists and require only asmall amount of support to hold them in place.Reflective insulation is often used for crawl spaces,but only dead air space should be assumed in calculatingheat loss when the crawl space is ventilated. A groundcover of roll rooting or plastic film, such as poly-ethylene, should be placed on the soil of crawl spaces todecrease the moisture content of the space as well as ofthe wood members.Insulation should be placed along all walls, floors,and ceilings that are adjacent to unheated areas. Theseinclude stairways, dwarf (knee) walls, and dormers of 11/2 story structures. Provisions should be made forventilating the unheated areas.Where attic space is unheated and a stairway isincluded, insulation should be used around the stairwayas well as in the first-floor ceiling. The door leading tothe attic should be weather stripped to prevent heat loss.Walls adjoining an unheated garage or porch should alsobe insulated. In structures with flat or low-pitched roofs,insulation should be used in the ceiling area withsufficient space allowed above for cleared unobstructedventilation between the joists. Insulation should be usedalong the perimeter of houses built on slabs. A vaporbarrier should be included under the slab.In the summer, outside surfaces exposed to thedirect rays of the sun may attain temperatures of 50°For more above shade temperatures and tend to transferthis heat into the house. Insulation in the walls and inthe attic areas retards the flow of heat and improvessummer comfort conditions.Where air conditioning is used, insulation should beplaced in all exposed ceilings and walls in the samemanner as insulating against cold-weather heat loss.Shading of glass against direct rays of the sun and theuse of insulated glass helps reduce the air-conditioningload.Ventilation of attic and roof spaces is an importantadjunct to insulation. Without ventilation, an attic spacemay become very hot and hold the heat for many hours.Ventilation methods suggested for protection againstcold-weather condensation apply equally well toprotection against excessive hot-weather rooftemperatures.The use of storm windows or insulated glass greatlyreduces heat loss. Almost twice as much heat loss occursthrough a single glass as through a window glazed withinsulated glass or protected by a storm sash. Doubleglass normally prevents surface condensation and frostforming on inner glass surfaces in winter. Whenexcessive condensation persists, paint failures anddecay of the sash rail can occur.CAUTIONPrior to the actual installation of theinsulation, consult the manufacturer’s specifi-cations and guidelines for personal-protectionitems required. Installing insulation is notparticularly hazardous; however, there aresome health safeguards to be observed whenworking with fiberglass.INSTALLATIONBlanket insulation and batt insulation with a vaporbarrier should be placed between framing members sothat the tabs of the barrier lap the edge of the studs aswell as the top and bottom plates. This method is notpopular with contractors because it is more difficult toapply the drywall or rock lath (plaster base). However,it assures a minimum of vapor loss compared to the losswhen the tabs are stapled to the sides of the studs. Toprotect the top and soleplates, as well as the headers overopenings, use narrow strips of vapor barrier materialalong the top and bottom of the wall (fig. 5-28, view A).Ordinarily, these areas are not well covered by the vaporbarrier on the blanket or batt. A hand stapler iscommonly used to fasten the insulation and the vaporbarriers in place.For insulation without a vapor barrier (batt), aplastic film vapor barrier, such as 4-roil polyethylene, iscommonly used to envelop the entire exposed wall andceilings (fig. 5-28, views B and C). It covers theopenings as well as the window and doorheaders andedge studs. This system is one of the best from thestandpoint of resistance to vapor movement. Further-more, it does not have the installation inconveniencesencountered when tabs of the insulation are stapled over5-22
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