How to Soundproof a Ceiling

How to Soundproof an Existing Ceiling

1. Remove the Lights and Obstructions

   Turn off the power to the room. Remove light fixtures, down to the electrical boxes. Leave the boxes in place. Cap off loose wires with wire nuts. Remove all other items from the ceiling like junction box faceplates, recessed light trim, smoke detectors, and ceiling hooks.

2. Lay the Drywall Upside-Down

   Protect the floor with plastic sheeting. Lay the first sheet of drywall flat on the floor, with its back side facing up.

3. Prepare the Soundproofing Compound

   Fit the soundproofing compound in the caulking gun. Pierce the top of the soundproofing compound tube to open it up. With the utility knife, cut off the end of the soundproofing compound plastic nozzle to produce a 1/4-inch to 3/8-inch diameter hole. It's important to cut the nozzle to the correct size so that the bead of compound will be the correct thickness.

4. Spread the Soundproofing Compound on the Drywall

   Lay out long beads of soundproofing compound on the drywall sheet. Keep a border around the perimeter clear of compound. Do not spread the compound. Instead, squirt it out from above in a random pattern. Each sheet requires 56 ounces of compound or about two tubes.

   Tip

   It's important to add the full amount of soundproofing compound. The difference between one and two tubes of compound adds about two more STC points to the soundproofing rating.

5. Lift the Drywall Sheet

   With an assistant, add the sheet of drywall to the drywall hoist. Keep the back side facing up. Raise the sheet and place it in a corner of the room, leaving a 1/4-inch gap against the walls. Make sure that the sheet is placed perpendicular to the existing sheets of drywall.

6. Screw the Drywall Into Place

   Screw the new sheet into the framing members behind the existing drywall panels every 12 inches using 2-1/2-inch drywall screws. Do not screw the sheet only into the upper drywall. An attachment to the framing is crucial.

7. Cut Around the Obstructions

   When you reach an obstruction, cut an appropriately sized hole in the sheet of drywall. Be sure to do this before adding the soundproofing compound.

   Tip

   Magnetic electrical box locator systems like Blind Mark or Center Mark pinpoint the position of boxes on drywall sheets.

8. Add the Box Extenders

   Add the electrical box or ceiling box extenders to allow the boxes to remain flush with the ceiling drywall, per electrical code.

9. Add the Soundproofing Sealant

   Remove the soundproofing compound from the caulking gun and replace it with the soundproofing sealant. Add the sealant to all ceiling cracks, around the drywall perimeter, and around electrical and ceiling boxes.

   Tip

   For improved soundproofing, consider using mass-loaded vinyl instead of soundproofing compound. Available in rolls, mass-loaded vinyl is a solid, dense sheet of extremely heavy vinyl that provides mass while keeping thickness to a minimum. One square foot of 1/4-inch mass-loaded vinyl weighs two pounds. A square foot of 1/8-inch-thick mass-loaded vinyl weighs one pound and costs about $2.50 per square foot.

10. Finish and Paint the Ceiling

    Soundproofing the ceiling is now complete. You can finish the drywall by taping and mudding seams. Later, prime the drywall and paint it with the desired paint color.

How to Soundproof a New-Construction Ceiling

1. Install Insulation Between the Joists

   Add fiberglass or mineral wool insulation between the ceiling joists. The compression-fit insulation should fit between the joists without the need for support. If the insulation does sag, use wire insulation support rods. Arch the support rods upward to hold the insulation in place.

   Tip

   At 6-1/4 inches thick, R-19 insulation is more than sufficient mass for soundproofing between floors. It's not necessary to fill the entire floor cavity. Mineral wool insulation is about 20-percent more expensive than fiberglass but is up to three times more dense, making it better for soundproofing.

2. Install or Adjust Projections

   Planned or existing ceiling projections like junction boxes, recessed lights, ceiling lights, and heating vents will need to be adjusted to account for the increased ceiling thickness. For 1/2-inch-thick resilient channel plus two layers of 5/8-inch drywall, the thickness will be 1-3/4-inch.

3. Add the First Layer of Drywall

   Install a layer of 5/8-inch drywall to the joists. Maintain a 1/4-inch gap around the perimeter. Do not finish the drywall. Be sure to create cut-outs for any projections.

4. Apply Sound Deadening Tape

   Apply the sound deadening tape to the seams between the sheets of drywall.

5. Plan the Resilient Channel Layout

   Sketch out the plan for the resilient channel layout. Channels must be installed perpendicular to the ceiling's framing members. No perimeter channels are required. The first row of channels begins no more than 6 inches from the wall and progresses every 24 inches for 16-inch on-center joists. With 24-inch on-center joists, the resilient channels should be spaced every 16 inches. The last row should stop no more than 6 inches from the wall. Resilient channels should not touch the walls.

6. Install the Resilient Channels

   Attach the resilient channels to the joists with 1-1/4-inch screws. Use type W, coarse thread screws to attach to wood framing members. Attach the channel at every available point. Be sure to attach the channels on the upper section of the S-shaped channel. Leave the lower section of the S-shape available for attaching the drywall.

7. Install the Drywall to the Resilient Channels

   Attach the 5/8-inch drywall sheets perpendicular to the resilient channels with fine-thread, type S drywall screws. Drive the screws into the resilient channels being careful to avoid penetrating both the channel and the joists.

   Tip

   Avoid short-circuiting your soundproofing system. Short-circuiting, a soundproofing term, means inadvertently creating a sound bridge between layers. Driving a screw into a joist rather than into the resilient channel is one form of short-circuiting.

8. Add Another Layer of Drywall (Optional)

   Depending on the local building code, your home's construction, and the type of resilient channels you choose, you may be able to add a second layer of 5/8-inch drywall. Do so if you desire greater soundproofing.

   This drywall thickness weighs 2-1/2 pounds per square foot. Many single-leg resilient channels are rated up to 7-1/2 pounds per square foot. Be sure to attach the second layer of drywall with appropriate-length screws to penetrate the underlying drywall and the resilient channel by one-half inch. Avoid penetrating the ceiling joists with the attachment screws.

9. Finish and Paint the Ceiling

   The ceiling can now be drywall-finished in a conventional manner by taping and mudding the seams and corners, sanding smooth the dried compound, and priming and painting the ceiling.

When to Call a Professional

Soundproofing companies or companies that specialize in home theater or sound installations may be able to provide advice and install ceiling soundproofing for you. If you have a ceiling soundproofing system in mind, most general contractors will be able to construct the system to your specifications.