These do-it-yourself instructions cover installation of batts and blankets, loose-fill or poured-in materials, rigid boards, and reflective insulations. Before beginning the work, read and observe the following precautions:
- Wear clothing adequate to protect against skin contact and irritation. A long-sleeved shirt with collar and cuffs buttoned, gloves, hat, glasses, and disposable dust respirator are advisable in all do-it-yourself insulation projects. Also, read the label and follow all the manufacturer's directions.
- Do not cover or hand-pack insulation around bare stove pipes, electrical fixtures, motors, or any heat-producing equipment such as recessed lighting fixtures. Electrical fire-safety codes prohibit the installation of thermal insulation within three inches of a recessed fixture enclosure, wiring compartment, or ballast, or above the fixture so that it will trap heat and prevent free circulation of air, unless the fixture is identified by label as suitable for insulation to be in direct contact with the fixture. THIS IS FOR FIRE SAFETY.
Also, if your home is very old, you may want to have an electrician check to see if the electrical insulation on your wiring is degraded or if the wires are overloaded. In either of these two situations, it may be hazardous to add thermal insulation within a closed cavity around the wires because that could cause the wires to overheat. If your home was wired using a now obsolete method called knob and tube wiring, the National Electric Code forbids the installation of loose, rolled, or foam-in-place insulation if the insulation would surround the wires and prevent heat dissipation from the electrical conductors to a free air space. THIS IS FOR FIRE SAFETY.
Do not cover attic vents with insulation. Proper ventilation, especially in attics, must be maintained to avoid overheating in summer and moisture build-up all year long.
Blanket Insulation: Batts and Rolls
Installing batts and rolls in attics is fairly easy, but doing it right is very important. On unfinished attic floors, work from the perimeter toward the attic door. In new construction, the vapor retarder facing should be installed with the facing placed down toward the ceiling gypsum board, except in hot humid climates where unfaced batts should be used. If reinsulating over existing insulation, it is recommended that unfaced batts be used. If there is not any insulation in your attic, fit the insulation between the joists. If the existing insulation is near or above the top of the joists, it is a good idea to place the new batts perpendicular to the old ones because that will help to cover the tops of the joists themselves and reduce heat loss or gain through the frame. Also, be sure to insulate the trap or access door. Although the area of the door is small, an uninsulated attic door will reduce energy savings substantially.
On walls, begin at the top and work down. Place the vapor retarder towards the lived-in side, except in hot humid climates. Fit the insulation between the wood frame studs, cut off the excess length where necessary, and secure the insulation by stapling the flanges of the vapor retarder according to the manufacturer's instructions. Cut the batt carefully to fit around obstructions with no gaps. Don't compress the insulation to fit behind pipes or wires. Instead cut to the middle of the batt's thickness so you have a flap under the wire and one over the wire.
The kraft paper or standard foil vapor retarder facings on many blanket insulation products must be covered with gypsum or interior paneling because of fire considerations. Some blanket products are available without these facings or with a special flame resistant facing (labeled FS25 - or flame spread index 25) for places where the facing would not be covered. Sometimes, the flame resistant cover can be purchased separately from the insulation. Also, there are special fiber glass blanket products available for basement walls that can be left exposed. These blankets have a flame-resistant facing and are labeled to show that they comply with ASTM C 665, Type II, Class A.
When a fiber glass blanket is used to insulate the inside of basement walls, it is necessary to attach wood furring strips to the walls by nailing or bonding; or to build an interior stud-wall assembly on which the interior finish can be attached after the insulation is installed. The cavity created by the added framing should be thick enough for the desired insulation R-value.
When a fiber glass blanket is used to insulate the walls of an unventilated crawlspace, it is sometimes necessary to attach wood furring strips to the walls by nailing or bonding. The insulation can then be stapled or tacked into place. Alternatively, the insulation can be fastened to the sill plate and draped down the wall. Because the insulation will be exposed, be sure to use either an unfaced product or one with the appropriate flame spread rating. If you live in a very cold region, you should continue the insulation over the soil for about two feet (on top of the necesssary ground vapor retarder discussed previously).
Batts and rolls must be cut and fit around such obstructions as cross-bracing between floor joists, and window frames in walls. Strips of insulation may be cut off and stuffed into tight spaces by hand. Do not hand-pack insulation around hot spots such as recessed light fixtures. THIS COULD CAUSE HEAT BUILD-UP AND MAY BECOME A FIRE HAZARD.
When batts or rolls are used overhead, such as above an unheated crawl space or basement, fit the insulation between the beams or joists and push it up against the floor overhead as securely as possible without excessive compaction of the insulation. The insulation can be held in place, either by tacking chicken wire (poultry netting) to the edges of the joist, or with snap-in wire holders. Don't forget to place insulation against the perimeter that rests on the sill plate (see Figure 1 ). If you insulate above an unheated crawl space or basement, you will also need to insulate any ducts or pipes running through this space. Otherwise, pipes could freeze and burst during cold weather.
Rigid Board Insulation
When rigid foam insulation boards are used to insulate the interior of masonry walls, they do not require added vapor retarder treatment. If foil-faced board is used, the foil side is placed toward the room. To install boards, wood furring strips should be fastened to the wall first. These strips provide a nailing base for attaching interior finishes over the insulation. Fire safety codes require that a gypsum board finish, at least ½-inch thick, be placed over plastic foam insulation. The gypsum board must be attached to the wood furring strips or underlying masonry using nails or screws.
When rigid foam insulation boards are used to insulate the walls of an unventilated crawlspace, they can be bonded to the wall using recommended adhesives. Because the insulation will be exposed, be sure to check the local fire codes and the flame-spread rating of the insulation product. If you live in a very cold region, you should continue the insulation over the floor of the crawl space for about two feet (on top of the required ground vapor retarder discussed previously). If you live in an area prone to termite damage, check with a pest control professional to see if you need to provide for termite inspections.
This insulation is most efficiently installed by blowing it into place with pneumatic equipment. This method effectively breaks up any lumps and incorporates air so that the insulation has the desired density and thickness. When using loose-fill insulation in new construction, install a vapor retarder on the living side (see earlier section on moisture control). When loose-fill is used as additional insulation, either placed over existing loose-fill or over batts or blankets, do not install an additional vapor retarder.
Loose-fill insulation must be prevented from shifting into vents, eaves, or from contacting heat-producing equipment (such as recessed lighting fixtures). Block off those areas with baffles or retainers to hold the loose-fill insulation in place.
Installing reflective insulation is similar to placing batts and blankets. Proper installation is very important if the insulation is to be effective. Study and follow the manufacturer's instructions. Often, reflective insulation materials have flanges that are to be stapled to joists in attics or floors, or to wall studs. Since reflective foil will conduct electricity, one must avoid making contact with any bare electrical wiring.
Radiant barriers may be installed in attics in several configurations. The radiant barrier is most often attached near the roof, to the bottom surface of the attic truss chords or rafter framing.