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Standard Practice for Installing Cellulose Building Insulation

Cellulose insulation can be installed in attics, walls, ceilings, floors, and other building assemblies using a variety of standard accepted techniques. This guide covers typical assembly designs and some of the more common installation methods that can be used to insulate new and existing structures.

This recommended practice covers the application of cellulosic thermal insulation in attics, sidewall cavities and between floors of single & multi family dwellings and other buildings by means of pneumatic equipment.

The purpose of this recommended practice is to inform installers, system designers and consumers of acceptable procedures to ensure proper installation. It also identifies some of the precautions which need to be taken.

ASTM Standards
C-168 Standard Terminology Relating to Thermal Insulating Materials
C-739 Standard Specification for Cellulosic Fiber (Wood Base) Loose Fill Thermal Insulation
C-755 Standard Practice for Selection of Vapor retarders for Thermal Insulation C-1149 Standard Specification for Self-Supported Spray Applied Cellulosic Thermal / Acoustical Insulation
C-1015 Standard Practice for Installation of Cellulosic and Mineral Fiber Loose-Fill Thermal Insulation
E-241 Standard Guide for Limiting Water-Induced Damage to Buildings
3.2 Federal Regulations
16 CFR Part 1209 Consumer Products Safety Commission Interim Safety Standard for Cellulose Insulation
16 CFR Part 460 FTC Trade Regulation Rule, Labeling and Advertising of Home Insulation

Backer board - a rigid, non vapor barrier forming material such as rock lath, treated cardboard, plywood, netting, etc. which is used to cover the open side of an existing wall and forms a cavity which may be filled with loose fill insulation. It must have sufficient strength to withstand the pressure developed when filling the cavity.
4.2 Blocking - a material used to retain the insulation in place in open areas.
4.3 Fill tube - a tube which enables a cavity to be filled through a single entry hole.


4.4 Enclosed ceiling cavities - a ceiling area which is covered on both top and bottom.

An inspection of the building shall be made prior to installation. A thermal camera and other inspection / diagnostic tools are recommended for before and after installation inspections when applying insulation in existing building. A moisture meter is recommended when installing stabilized cellulose insulation in both new and existing sidewalls.
5.2 The installing contractor shall examine all surfaces and substrates to be installed upon and ensure that they are in a suitable state. Any surfaces or substrates that are wet, damaged or have any signs of mold should not be insulated until these problems are corrected. Special consideration should be given to the following areas.
5.2.1 Holes in ceilings or sidewalls, that would allow the insulation to escape, should be sealed.
5.2.2 Weak areas of interior walls that may not be able to withstand pressures during the filling operation should be reinforced.
5.2.3 Walls with alterations, such as built-in bookshelves and cabinets, which create isolated cavities, will require special entry holes.
5.2.4 Wall cavities, which are used as air ducts for heating or air conditioning systems, must not be filled with insulation.
5.2.5 Openings in heating or air conditioning air systems, in insulated areas, must have blocking placed around them.
5.2.6 Wall cavities, which open into basements or crawl spaces, must be sealed.
5.2.7 The external siding of existing buildings should be inspected for paint peeling or other evidence of moisture problems. Insulation alone may not solve such problems. Other remedial actions may be necessary. (See Sections 9 and 10 for some of the steps to be taken.)

New Construction
6.1.1 Where individual vents are used in the soffit, the rafter space immediately in front of and on either side of the vent should be provided with an air chute (see Fig.1A and Fig. 1B). Other spaces should be totally blocked.
Where a continuous strip vent is used in the soffit, an air chute should be provided in every rafter space (see Fig. 1A and 1B).

Attic soffit diagram 1A

Figure 1A

6.1.3 All voids around windows and doors should be sealed to stop air infiltration. Various materials such as foam backer rod or urethane spray foam are available for this purpose. See Note 1.

Note 1 - Some window manufacturers will not honor warranties if foam is used, even if the foam is non-expanding. Check with window manufacturer for approved sealing procedures and materials.

6.1.4 Insulating the corners of attics in buildings with hip roofs may require special nozzles or placement tools. Alternately, corners can be insulated with suitable insulation before the drywall or plasterboard is installed. Any other areas inaccessible after the interior finish is installed must be handled in like manner.


6.2 Existing Structures
In joist areas, where soffit vents are installed, the opening from the attic into the soffit area may be treated as described in 6.1.1 and 6.1.2. Install chute as per Figure 1B.
6.3 New and Existing structures
6.3.1 Blocking should be placed around access to the attic to prevent insulation from falling out.
Blocking should be placed around recessed lights, heating fixtures, exhaust flues of furnaces, water heaters, space heaters or other heat-producing devices. Clearance between heat producing elements and combustible constructions should follow applicable codes. Blocking should be permanently placed so as to keep insulation a minimum of three inches away from all sides of recessed lighting fixtures and other heat-producing devices. The open area above recessed lighting fixtures and other heat-producing devices should not be insulated per the National Electrical Code and the Consumer Protection Safety Commission.

Attic soffit diagram for airflow 1B

Figure 1B

6.3.3 Cabinet bulkheads, stairway wells and wall cavities which open into the attic should be covered by a retainer to support the insulation. (See 4.1)
6.3.4 The open side of any wall between a heated and unheated area should be covered by a retainer to form a cavity to retain loose fill material.
6.3.5 See section 11 for areas requiring specific attention and care prior to installation.

When installing insulation, installers must not exceed maximum square feet coverage per bag, and must install both the minimum number of bags per 1000 square feet and the stated initial installed thickness to ensure that the stated R-value is achieved.

Coverage may vary as much as 10% without significantly affecting the stated R-value as long as the installation instructions are followed. Actual coverage will vary depending on applicator's technique, machine type and settings, hose type and length, ambient temperature and humidity, etc. Stabilized insulations will also vary in coverage based on condition of spray tips, amount of moisture added, etc.

When installing insulation by pneumatic means, it is important that the application machine be set as recommended by the manufacturer. Tuning of machine settlings to match equipment wear and environmental conditions is to be expected.

Install insulation per the coverage requirements noted in section 7, 11 and ancillary installation documents such as: fact sheet, moisture loading per bag (if using a stabilized product), standard operating procedures, etc. Additional documents include, but are not limited to: ASTM Standard Designation C1015, Consumer Products Safety Commission 16 CFR Part 1209, local and national building & fire codes, Federal Trade Commission 16 CFR Part 460, etc.
8.1 Ceiling Areas
8.1.1 Accessible Ceilings
Apply insulation uniformly and to the desired minimum thickness and square-foot weight across the entire area. Additionally, note sections 6, 7, 8.0, 10 and 11: which detail areas that require additional care, attention and or reference additional documents.
8.1.2 Enclosed Ceiling Cavities
Installations of this type must be made by pneumatic means and the cavity should be completely filled. This is done by inserting a fill tube into each cavity and withdrawing it as the cavity is filled. With cathedral ceilings, loose-fill insulation is to be installed at or above 3.5 pounds per cubic feet (pcf)
8.2 Sidewalls (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 blocks or other obstructions with an electrician’s fish tape or other similar tool. A mathematical check should be made in the first few stud space to assure that the proper amount of insulation is being installed
8.2.1 Filling through external siding in applications of this type, the following procedure is recommended. Drill holes 5/8 inch to 2 inches (1.59 to 5.08 cm) in diameter, depending on the siding, in each wall cavity. Vertical distance between a hole and top or bottom plate should not exceed 2 feet (.62 m) and the vertical distance between holes should not exceed 5 feet (1.52 m). 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 inch to 3/4 inch (1.59 to 1.9 cm) in diameter drilled in the mortar joints. All holes should be filled with suitable plugs. (See Figure 3).

Reccomend hole locations for dense-packing existing wall

Figure 3 


8.2.2 Filling with 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 inches (45.72 cm) of the plate farthest from the point of entry. Fill tube size will depend upon the size of hole which can be drilled. (See Figure 4 for alternate points of entry for the fill tube.

Existing wall insulation diagram

Figure 4

8.3 Sidewalls (New Construction)
The same installation techniques used with existing walls are occasionally employed in new construction (see section 8.2 with the addition that restraining material such as fabric is used to enclose walls prior insulation installation and final covering.) Insulation is usually installed in new walls before the walls are closed using Applegate's wall-spray system which uses a Stabilized Cellulose Insulation.
8.3.1 Applegate Stabilized Cellulose Insulations should only be installed by a professional insulation applicator using equipment and application procedures especially designed for this product and application. The insulation is sprayed into the wall cavities from inside the building, using a water mist to activate a dry adhesive in the stabilized insulation. Applegate Insulation's instructions with regard to application equipment and its use should be followed explicitly, as should Applegate's instructions on the amount of liquid to be used during application. All pipes, ducts, conduits, wiring, outlets, etc. should be installed in the wall before the insulation is applied. Windows and areas from which insulation is to be excluded, such as electrical boxes, should be masked using duct tape. Additionally, 2 or 4 mil Polyethylene sheeting works well for covering larger, finished areas such as windows and fireplaces.
8.3.2 After application the insulation is made even with the stud faces by a "stud scrubber." Do not install interior finish until the insulation moisture content is within the guidelines set forth in precautions 11:9and 11:10. For details regarding sprayed wall cavity insulation please see the, Standard Practice for the Installation of Sprayed Cellulosic Wall Cavity Insulation.

Most authorities agree that vapor retarders of any type should not be used with spray-applied cellulose. This recommendation may conflict with some building codes, but knowledgeable code officials understand the special nature of wall-spray cellulose and normally grant exceptions when the material is used.

Consult local or state building codes about the use of vapor retarders if applicable. Most authorities agree that vapor retarders of any type should not be used with wall-spray cellulose. This recommendation may conflict with some building codes, but knowledgeable code officials understand the special nature of wall-spray cellulose and normally grant exceptions when the material is used. See section 11.10 for precautions if required to use a vapor retarder with Applegate Stabilized Cellulose.
9.2  A ground surface vapor retarder such as plastic film is recommended when there is a crawl space beneath the floor. (See Section 10.0 for Ventilation)

Attic Ventilation
10.1.1 In vented attics without vapor retarders standard practice is to provide one square foot (.093 m2) of net vent area for each 150 square feet (13.94 m2) of ceiling area.
10.1.2 In vented attics with vapor retarders standard practice is to provide one square foot (.0903 m2) of net vent area for each 300 square feet (27.87 m2) of attic floor area.
10.1.3 When using a combination of roof and eave vents, and no ceiling vapor barrier, there should be 1 square foot (.093 m2) of net vent area for each 300 square feet (27.87 m2) of ceiling area. Vents should be installed with 50% of the total area in the eaves and 50%of the total area in the roof near the peak.
10.2 Unconditioned Crawl Space Ventilation
There should be 1 square foot (.093 m2) of net vent area for each 150 square feet (13.94 m2) of floor area.
10.3 "Conditioned" Crawl Spaces
No ventilation is required. Instead, line crawl space floors with a plastic vapor barrier extending up the crawlspace wall 4-6" sealing all seams; insulate crawlspace walls; and introduce conditioned air into crawlspace.


Heaters and recessed light fixtures must not be covered by the insulation, unless the fixture has an IC rating. Local and national codes must be followed if applicable. A minimum of 3 inches (7.62 cm) of air space must be maintained between fixtures (exhaust flues of furnaces, water heaters, space heaters or other heat-producing devices) and the blocking.
11.2 Cold air returns and combustion air intakes for hot air furnaces must not be blocked or insulation be installed in a manner that would allow it to be drawn into the system.
11.3 Insulation must not contact chimneys or flues in excess of 180 degrees. A minimum of 3 inches (7.62 cm) of air space must be maintained with blocking used to retain the insulation.
11.4 The homeowner should be advised that in tightly constructed homes or when insulating existing homes which have fuel fired heating systems within the living area or basement, an air duct must be installed between the furnace room and a well ventilated outside area to provide combustion air. A local heating contractor should be contacted for proper duct size and installation.
11.5 The homeowner should be advised that the relative humidity within the living area should be kept below 40% R.H. when outside temperatures fall below 32 degrees F. (0 degrees C.)
11.6 Applegate Cellulose Insulation is not recommended for filling the cavities of masonry walls.
11.7 Applegate Cellulose Insulation is not recommended for installation in or in contact with below grade exterior walls and or floors
11.8 Applegate Stabilized Cellulose Insulations should only be installed by a professional insulation applicator using equipment and application procedures especially designed for this product and application. A water pH factor greater than 7.8 requires Applegate Bora-Spray insulation or a pH buffer must be added to the water to reduce it's pH below 7.8. The instructions on the amount of liquid to be added and the recommended moisture content of the product during application must be followed.
11.9 When used in an enclosed cavity, adequate drying time after installation is required before covering. While many variables affect the length of the required drying time, the moisture content must be 20% or lower before enclosing the insulation if no vapor retarder is used.
11.10 The moisture content of Applegate Stabilized Cellulose Insulations and the ambient moisture of surrounding building materials, such as framing members, must be in equilibrium prior to activation of air conditioning or prior to covering if used in conjunction with a vapor retarder. Typically moisture equilibrium will be achieved around 12% moisture content, however, moisture equilibrium must be verified at each job as ambient conditions have a profound impact on moisture content and drying times.
11.11 This insulation is to be used in the temperatures range of -50 degrees F. to 180 degrees F. (-45.6 degrees C to 82.2 degrees C.)
11.12 It is recommended that the installers wear a dust mask and goggles.
11.13 Installers and specifiers are advised to refer to other relevant documents, including the National Electrical Code, ASTM Standard Designation C1015, Applegate moisture loading and SOP sheets, etc., for additional information.

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