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Standard Practice for the Installation of Sprayed Cellulosic Wall Cavity Insulation

Cellulose wall cavity spray insulation is rapidly growing in popularity among new home builders and buyers. This guide is a general outline of the methods and practices that have been found to result in satisfactory cellulose wall-spray installations.

1.1 This recommended practice covers the application of Applegate Stabilized Cellulose insulation (ASC) into wood/steel framed cavities of single, multifamily dwellings, and commercial buildings.
1.2 ASC is limited to vertical enclosed or covered applications.
1.3 When installing ASC materials, it is essential that the guidelines of the manufacturer are followed. This Standard Practice is not intended to supersede local, state or federal codes.
1.4 This Standard Practice assumes that the installer possesses a good working knowledge of the applicable codes and regulations, safety practices, tools, equipment, and methods necessary for the proper installation of ASC. It also assumes that the installer understands the fundamentals of residential construction that affects the installation of insulation materials.

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 that need to be taken. This recommended practice was prepared after consulting with the Technical Committee of Insulation Contractors Association of America (ICAA), numerous manufacturers, and the Department of Housing, and Urban Development, Use of Materials Bulletin No. 80.

3.1 ASTM Standards
C-168 Standard Terminology Relating to Thermal Insulating Materials
C-739 Specifications for Cellulosic Fiber (Wood Based) Loose-Fill Thermal Insulation
C-755 Standard Practice for Selection of Vapor Retarders for Thermal Insulation
C-1015 Standard Practice for Installation of Cellulosic and Mineral Fiber Loose-Fill Thermal Insulation
C-1149 Standard Specification for Self-Supported Spray Applied Cellulosic Thermal/Acoustical 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


Overspray – that portion of material from a spray pattern not filling or adhering to intended substrates.
4.2 Spray Nozzle – a tube with a liquid atomizing unit attached to intermix fibers and liquid. These nozzles can have various numbers and configurations of spray tips.
4.3 Wall Scrubber – a tool, with a rotating brush, that grooms the insulation level with the face of the studs.

5.1 An inspection of the building is essential prior to installation. Special considerations to the following areas is very important.
5.2 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.

5.3 Seal all vertical plumbing and electrical penetrations through both top and bottom plates of all walls according to local, state or federal codes.
5.4 It is best to cover finished areas including windows, doors, fireplaces, etc. It is faster to protect finished surfaces than to clean them later. 2 or 4 mil. Polyethylene sheeting works well.
5.5 Protect electrical boxes and other boxes on walls that are being sprayed, until the spraying is complete. Duct tape works well.
5.6 If recycling the ASC, a clean work area is important. Objects such as nails, wood, wire, etc., could damage the machine. Sweep these from the floor before starting to spray the ASC.
5.7 The installing contractor shall examine all surfaces and substrates to be sprayed. Any surfaces or substrates that are wet, damaged or have any signs of mold should not be sprayed until these problems are corrected.

6.1 The insulation shall be applied with spray application machines, spray nozzles, and other necessary equipment, in accordance with manufacturer’s instructions.
6.2 Semi-spiral hose shall be used. This hose allows the material to tumble and stay in the air stream.
6.3 A pump capable of providing 300 pounds per square inch (PSI) at a flow rate of 55 gallons per hour will work well in most every case. Diaphragm pumps have been found to be adequate. They are very forgiving and supply a constant pressure.
6.4 There are many nozzles to use and various configurations. Nozzles should be 2”, 2.5”, or 3” to facilitate good volume of material. Some have two spray tips, while others have up to six spray tips. Either way, the control of fiber to water ratio must be consistent. The liquid pressure line must be rated to handle the pressures that the pump is delivering. Applegate recommends stainless steel tips, as they last longer and wear less quickly than brass tips. As tips wear additional water is used, which can negatively affect the coverage per bag and moisture loading of the insulation. Regardless of what type of tip is used, installers must test their tips regularly and adjust the water flow and pressure to ensure that excessive water is not being applied.
6.5 A wall scrubber should be used for removing excess material from the wall and cleaning the face of the stud. This does a superior job and will quickly pay for itself in labor savings.
6.5.1 When using a wall scrubber, refer to the manufacturer or supplier for recommendations of safe and correct us of the wall scrubber.
6.6 A moisture meter should be available to monitor the moisture content during application and while the ASC is curing.
6.7 Large commercial vacuums may be used to aid in the recycling process (see Section 9). Some machines have vacuum systems attached that blend the recycled cellulose. Otherwise, vacuum systems may be added to machines.

6.8 Other items include:
6.8.1 Water Tank
6.8.2 Shovels, Brooms, Trash Cans (for recycle)
6.8.3 Staple Gun and Webbing
6.8.4 Stiff Kitchen Broom

7.1 The blower machine may be mounted in a truck or trailer to be positioned at the job site as close to a door as practical to make recycling easier and increase production. An alternative is to take a small machine into the building in a central location. This works very well when spraying in cold weather.
7.2 The pump should be positioned so it may operate according to manufacturer’s recommendations. Some larger gas machines have the pump mounted to the blower machine and powered by the gas engine.
7.3 At the job site, pull the hose to the farthest point you will insulate. Extend the hose no longer than necessary (100’ min.) having as few bends as possible. Next, pull the water line out along the insulation hose. Temporarily attaching the water line to the last ten or twelve feet of insulation hose helps avoid tangles while moving around the work area.
7.4 Connect the blower hose to the nozzle loosely, for easier direction of the nozzle. It is best to not tape the nozzle to the hose.


7.5 Adjust the blower machine and pump according to manufacturer’s recommendations. Refer to manufacturer’s recommendations for the correct pressure settings for the nozzle in use. Normally the liquid to fiber ratio should be between 1.3 to 1.75 gallons per bag of insulation. For instance a 26.5 lbs. bag of insulation at 1.3 gallons would result in a moisture content by weight of 27%. At 1.75 gallons it would be 35%. Higher moisture levels are unnecessary and should be avoided, as it increases drying time and may cause additional problems. Liquid flow tests should be made periodically to ensure a proper liquid to fiber ratio. In order to install ASC properly, these procedures must be followed.

8.1 The angle of spray is an absolutely essential part of spraying and must become a habit. A straight or downward angle of approximately 5 to 10 degrees and about two to four feet away from the wall gives a layering effect. When spraying layers upon layers, the cavity becomes one solid mass, with no inner voids and giving structural integrity. To fill the very top, under the plate, turn the nozzle angle up and step in a little closer to pack the insulation against and into the top of the cavity. After the top portion is almost full, step back and level out the nozzle to finish the cavity. Be careful not to over fill the top portion of the wall cavity. The cavities under windows, soffits, etc. must be treated the same as the top plate.
8.2 Filling the cavity to the proper thickness comes with experience. Wiping off the stud to get a better idea of the actual thickness in the cavity, will help in learning to judge the thickness of the over spray and help to keep it to a minimum. A smooth and steady movement of the nozzle will also help to decrease the amount of over spray. Many new applicators have problems with fall out. There are three principles to know about fall out:
8.2.1 The deeper the wall cavity or the wider the distance between studs, the more weight is pulling on the sprayed insulation. Therefore, it is very important to know the fiber to water ratio and keep it consistent. The deeper or wider the wall spacing, the more important this becomes. Framing up to 2x8, 24” OC can be successfully sprayed with the right equipment, material, and technique.
8.2.2 Do not install material at less than 2.5 pcf. Additionally, do not exceed 2.8 pcf as the additional weight doesn't improve the performance of the insulation, extends drying time and increases the likelihood of fallout.
8.2.3 The angle of the nozzle and the velocity of the material are the two most important factors to reduce fall out. The sprayed insulation must hit the substrate and stay. This can only be achieved with the proper angle. If the angle is not correct, the material will tend to deflect or slide off the studs and substrate. This can be mastered with practice and training.
8.3 Interior finish may be installed when the insulation is sufficiently dry, having a measured moisture content of 20% or less if no vapor retarder is used. The insulation moisture content 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.

9.1 When recycling, the material must be mixed properly or problems are likely to occur. If mixed improperly, the wall cavity insulation may be too wet, causing inconsistent flow. This can lead to instability and potentially, causing the insulation to fall out of the wall cavity. There are advantages and disadvantages to using the recycling method.
9.2 Advantages of recycling:
9.2.1 When recycling the material, all of the insulation is used, therefore there is very little waste. This also reduces the need for disposing of the excess material.
9.2.2 Carefully adjust moisture or fiber volume when the recycling method begins. The recycled material adds moisture mixed with the dry product. Adjusting the water pressure or changing the spray tips, will help maintain the same moisture percentage throughout the job.
9.3 Disadvantages of recycling:
9.3.1 Machine damage and down time are the most crucial items to consider. This can occur when foreign objects such as nails, wood, and other objects go through or get stuck in the machine.
9.3.2 The recycling method can be more time consuming. Normally, there is need for approximately 3 persons to each crew. This is a minimum; larger jobs may require a crew of 4. The type of machine can also factor in how much recycle material can be used. This can slow down the process and cause an over supply of recycled material. It is critical that the right equipment is used.
9.3.3 Mixing the recycled with the dry product is very important and can make or break the best sprayers. The material must be blended consistently.

10.1 ASC can be applied successfully in freezing or high humidity conditions. Always consult Applegate for recommendations on spraying in severe/adverse climates and conditions.
10.2 Heating the building while spraying may be necessary in extremely cold temperatures.
10.2.1 If the material doesn’t bond to studs and sheathing, it may be necessary to temporarily heat the building. In below freezing temperatures, the entire spray system can freeze up. The most vulnerable is the pressure hose and the nozzle. The pump and the inlet pump hose can also freeze.
10.2.2 ASC may take longer to dry in colder conditions. It may be necessary to use supplemental heat sources until moisture equilibrium is achieved if a vapor retarder is used or, until moisture content measures 20% or less if no vapor retarder is installed. Heat sources that add moisture to the air should be avoided, and it is imperative that provisions be made for the safe use of such heat sources and for the ventilation of moisture to the outside of the structure.
10.2.3 Opening windows and taking other steps to allow for free air changes through the structure may also aid the drying process.
10.3 In high humidity conditions, it may be necessary to use a dehumidifier until moisture content reaches 20% or less if no vapor retarder is used or, moisture equilibrium is achieved if a vapor retarder is used.

11.1 ASC is excellent for sound control. It can be used in walls between rooms and other areas that require sound control. Consult Applegate Insulation for the recommendations of the type of sound control that is needed for each configuration.


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 13.10 for precautions if required to use a vapor retarder with ASC.

13.1 Heaters and recessed light fixtures must not be covered by the insulation. Local or Federal codes must be followed if applicable. It is recommended that a minimum of 3 inches of air space be maintained between any non-I.C. rated fixture and the blocking.
13.2 Cold air returns and combustion air intakes for hot air furnaces must not be blocked and the insulation should not be installed in a manner which would allow it to be drawn into the system.
13.3 Insulation must not be allowed to contact chimneys or flues with temperatures in excess of 180 degrees. A minimum of 3 inches of air space must be maintained with blocking used to retain the insulation.
13.4 Applegate Cellulose Insulation is not recommended for filling the cavities of masonry walls.
13.5 Applegate Cellulose Insulation is not recommended for installation in or in contact with below grade exterior walls.
13.6 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.
13.7 This insulation is to be used in a temperature range of -50° F. to 180° F.
13.8 It is recommended that the installers wear a dust mask and goggles.
13.9 This insulation should only be installed by a professional insulation applicator using equipment and application procedures especially designed for this product and application. The instructions on the amount of liquid to be added and the recommended moisture content of the product during application must be followed. 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.
13.10 The insulation moisture content 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.
13.11 Installers are advised to refer to and follow other relevant documents, such as but not limited to, the National Electrical Code, ASTM Standard Designation C 1015, etc.

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