Application procedures

Ceiling areas. When installing insulation by pneumatic means in accessible ceilings, it is important that the blowing machine be set as recommended by the machine manufacturer. Specifiers do not need to compensate for settling in attics because federal law (the CPSC standard and the FTC R-Value Rule) requires R-value and coverage data to be stated at settled density. Specifiers, installers, and buyers need to understand that the “minimum thickness” col­umn on cellulose coverage charts represents settled thickness if the chart has only one thickness column. The “bag count” and “weight” columns are the “official” coverage statements.4

Installations in enclosed ceiling cavities must be made by pneu­matic means, and the cavity should be filled completely. This is done by inserting a fill tube into each cavity and withdrawing it as the cavity is filled. The air setting on the machine should be set as rec­ommended by the machine manufacturer for sidewall application. Coverage will be proportional to that shown on the manufacturer’s coverage chart under sidewalls, depending on the cavity size.8

Sidewalls in existing buildings. Installation into sidewall cavities must be made by pneumatic means. The air setting on the machine should be set as recommended by the machine manufacturer according to the size nozzle being used. After fill holes are drilled, all cavities should be checked for fire blocking or other obstructions with an electrician’s fish tape or other similar tool. A mathematical check should be made in the first few stud spaces to ensure that the proper amount of insulation is being installed. Installers also should verify with the manufacturer’s coverage chart.8

In wall applications, standard practice is to compact loose-fill cel­lulose to a density that will prevent settling. While this is a matter of some controversy, most authorities recommend a density of at least 3.0 lb/ft3 for cellulose insulation in walls. Materials with high nominal settled densities (2.0 lb/ft3 and higher) should be installed at 3.5 lb/ft3. Research has confirmed that settling is virtually nil with any cellulose insulation at densities of 3.5 lb/ft3 or higher. Compacting cellulose insulation may produce a very slight reduc­tion in R-value.4

If filling the wall cavity through the external siding in an exist­ing building, the following procedure is recommended by СІМА. First, drill holes from 5/8 to 2" in diameter, depending on the siding, in each wall cavity. The vertical distance between the access holes and the top or bottom plate should not exceed 2 ft; the vertical dis­tance between the holes should not exceed 5 ft. Homes with shin­gle or lapped siding should have the holes drilled as near the shadow line as possible. Homes with brick veneer should have holes 5/8 to 3/4M in diameter drilled in the mortar joints. All holes should be filled with suitable plugs8 (Fig. 7.7).

Filling the wall cavity with a fill tube in some applications is desirable. When using this method, only one entry hole per cavity is necessary. The fill tube should be inserted far enough to reach within 18" (45.72 cm) of the plate farthest from the point of entry. Fill-tube size will depend on the size of hole that can be drilled (see Figs. 7.8 and 7.9 for alternate points of entry for the fill tube).

Application procedures

Figure 7.7 Installation holes. {СІМА)

Application procedures

Sidewalls in new buildings. Various types of permanent retainer sys­tems are used to install dry cellulose insulation in new walls. All systems are proprietary, and the manufacturers provide detailed instructions and often special training programs for their use. All systems require pneumatic installation and compression of the material to sufficient density to prevent settlement. The Insulation Contractors Association of America (ICAA) recommends a density of 1.5 times nominal settled density for sidewall installations. Some manufacturers recommend an installed density of at least 3.5 lb/ft3 in sidewalls.

Dry cellulose insulation can be installed in new walls using tem­porary retainers that are clamped in place to create a closed cavity.

Application procedures

Insulation is blown into the temporary cavity at sufficient density to keep it in place when the retainer is removed.

One manufacturer of a proprietary product uses a polyester tire chord vapor retarder as the retainer during installation. Convenient access to the cavity is advantageous and allows visual inspection of the process during installation. The ParPac system uses any loose – fill cellulose insulation and is installed at a density of 3 lb/ft3, result­ing in an R-value of 3.61 per inch (Figs. 7.10 and 7.11).

Vapor retarders. As discussed in Chap. 4, the need for vapor retarders and their proper location within a wall assembly are influenced by the interior and exterior environmental conditions as well as the wall’s thermal and vapor flow characteristics. It is important to note that each building is fairly unique in terms of wall construction, interior use, and environmental conditions, and should be evaluated individually by the building designer. The homeowner also could consult an insulation manufacturer and building code official for recommendations on where to place a vapor retarder.

When installing loose-fill insulations, a material such as 6-mil (0.006м) polyethylene plastic sheeting can be used as a vapor retarder. Some cellulose manufacturers recommend against use of vapor retarders in walls insulated with spray-applied cellulose.

Application procedures

СІМА is not aware of any endemic problems resulting from this practice.

A vapor retarder is typically not required under attic insulation when the attic is adequately ventilated, but a vapor retarder must be used when the cold side of ceilings cannot be ventilated. A ground-surface vapor retarder such as plastic film is recommended when there is a crawl space beneath a floor.

In existing construction, most cellulose producers regard vapor retarders as unnecessary with dense-pack cellulose under most conditions. If design temperatures are below — 15°F (—26°C), the interior surfaces of exterior walls and ceilings where the cold side cannot be ventilated can be painted with a vapor barrier paint. As with new construction, a ground-surface vapor retarder, such as plastic film, is recommended when there is a crawl space beneath a floor.

Ventilation. Ventilation guidelines are specified in the locally adopt­ed building codes. The more stringent requirement should be used if the following СІМА guidelines contradict with the building code. In vented attics without vapor retarders, standard practice is to provide 1 ft[7] [8] [9] [10] [11] of net vent area for each 150 ft2 of ceiling area. In vent­ed attics with vapor retarders, standard practice is to provide 1 ft2 of net vent area for each 300 ft2 of attic floor area. When using a combination of roof and eave vents and no ceiling vapor barrier, there should be 1 ft2 of net vent area for each 300 ft2 of ceiling area. Vents should be installed with 50 percent of the total area in the eaves and 50 percent of the total area in the roof near the peak. If the residence is built over an unheated crawl space, there should be 1 ft2 of net vent area for each 150 ft2 of floor area.