How to Use Soundproofing Foam Spray

Silence really can be golden when it comes to the rooms in your house. The trouble is that sound, like air, can sneak through your home’s walls ruining the peace of your down time. Spray foam prevents noise from disrupting your interior by filling wall cavities that don’t contain other forms of insulation. As a bonus, you’ll be making your home more comfortable and much more energy efficient.

Things You'll Need

• Stud finder
• Pencil
• Masking tape
• Plastic drop cloth
• Clean rags
• Power drill
• 3/4-inch bit
• Respirator
• Tyvek coverall suit
• Safety goggles
• Nitrile gloves
• Spray foam insulation kit
• Wall compound
• Sanding pad

Instructions

Preparation

1. Locate and mark the studs along the wall you intend to soundproof, using a stud finder and pencil. Also locate and mark the location of any blocking, horizontal 2-by-4 members installed between studs as fire protection.

2. Tape down a plastic drop cloth, covering 4 to 5 feet of floor in front of the wall. Set aside a few damp rags to clean up any spillover.

3. Drill three 3/4-inch holes in each wall cavity. The first hole should be 30 to 32 inches above the floor, the second should be 32 inches above the first, and the last should be right below the ceiling. You may have to adjust this spacing to accommodate blocking or other obstructions such as wiring and electrical boxes, as well as the ceiling height.

4. Buy your foam kit. Most manufacturers provide a simple formula for the amount of foam you’ll need based on the wall’s square footage.

5. Dress in the appropriate safety gear. This includes a respirator approved by NIOSH for use with polyurethane sprayed materials, safety goggles, a Tyvek coverall suit, and nitrile gloves. Most manufacturers offer complete safety kits containing all these components.

Spraying

1. Rock the foam canisters back and forth for a minute or two. Connect one end of the hose to the canister, and the other end to the gun.

2. Open the valve on the canister. Hold the spray gun with the nozzle inserted into a bottom hole and press the trigger. Count slowly to 13 and stop spraying.

3. Check the hole. The foam should be rising up inside of the wall to the level of the next hole. If it begins to breach the hole, use a rag to block the opening.

4. Replace the spray gun nozzle. The nozzle will clog if the gun is allowed to sit for more than 30 seconds. Move to the bottom hole on the next wall cavity and begin spraying. Adjust your count to reflect the actual time it took for the foam to reach the hole above.

5. pray foam in all the cavities up to the second hole, working side to side, and then repeat up to the top of the wall cavities. Replace the nozzle whenever it becomes hard to spray the foam.

6. Fill the holes with wall compound, sand when dry, and paint the wall. Remove the drop cloth and throw it away with the coveralls and gloves.

Tips & Warnings

• Modern non-load-bearing walls are often framed with metal studs. If your stud finder cannot locate the studs, try a hand-held metal detector.

• When working around a blockage, or if you just want to increase the control you have over the stream of foam, consider using a 2-foot length of 5/16 inch hose attached to the nozzle of the gun. By sliding the hose into the hole, you may be able to better judge the rising foam. If you choose to work this way, you’ll have to regularly replace the hose because it will become clogged as the foam hardens.

• Any workspace in which expanding foam is sprayed must be adequately ventilated. Use a window fan to remove any residual vapors that leak out of the holes in the wall.

References

• Spray Polyurethane Foam Alliance; I’m a Do-It-Yourselfer Installing Spray Polyurethane Foam

Resources

• U.S. Department of Energy; Energy Efficiency and Renewable Energy; Energy Savers; Your Home; Sprayed-Foam and Foamed-In-Place Insulation
• “Green Building & Remodeling for Dummies”; Eric Corey Freed