How to Soundproof a Basement Ceiling

When an unfinished basement becomes living space, the effect of sound from upstairs on those downstairs — and vice versa — is often overlooked. The TV sound system in an upstairs living room sounds amazing, but not if you’re trying to work in your basement office. Same if you’re trying to sleep on the first floor when there’s a big game on the basement TV.

With the right materials and know-how, you can massively reduce these noise issues. Soundproofing your basement ceiling isn’t difficult or complex, as long as you do the work before the space is finished. If your basement ceiling is already drywalled and painted, you’ll need to remove that drywall before soundproofing can happen.

Still, if you have a serious noise issue, it’s worth the trouble. Proper basement ceiling soundproofing will greatly reduce upstairs noise heard in the basement and basement noise heard upstairs. Keep reading to learn how to soundproof a basement ceiling.

Gather These Materials

Fire code drywall

Drywall is a great soundproofing material. It’s dense and absorbs sound. Combined with tape and drywall compound, it forms an unbroken, crack-free surface. Here are a few tips for soundproofing your house.

The 5/8-inch fire code drywall is commercial quality and a much better choice for soundproofing than the regular 1/2-inch thickness. But a single layer of drywall isn’t enough — you’ll need four. This might seem excessive, but it’s part of a basement ceiling soundproofing approach I’ve used with great success over the years.

Green Glue soundproofing compound

Green Glue comes in caulking tubes. It’s the best stuff I know to seal cracks between sheet material in your basement ceiling and improve soundproofing. The rubbery compound absorbs sound while sealing basement ceiling cracks that transmit noise. Use it on all cracks between the subfloor and drywall sheets. Find out how you can keep the mold away with basement subfloor panels.

Fiberglass or mineral wool insulation

Lots of sound-absorbing material is an important defense against noise coming through a basement ceiling. That’s where good old fiberglass or mineral wool insulation can help.

The joist cavities in basement ceilings are typically empty, because there’s usually no temperature-related reason to insulate them. But if soundproofing is your goal, getting enough fluffy insulation to fill all those cavities is crucial.

Wooden cleats

You’ll need something to hold that insulation in place. I cut 1-1/2- by 1-1/2-inch strips of wood, then screw them to the faces of each basement ceiling joist with 2-1/2-inch deck screws. Buy enough 2×8 lumber to make all the strips you need, then use a table saw to rip cut it to 1-1/2- by 1-1/2-inch.

Metal hat channel and sound isolation clips

The subfloor of the room above and the drywall of the basement ceiling are both usually fastened directly to the floor/ceiling joists. That lets lots of noise and vibration through from one story to the next.

This is where uncoupling strips and clips come in. Strips of hat channel and sound isolation clips create space between the ceiling and the joists, making it much harder for noise and vibration to carry through.

Buy enough hat channel to cover the entire width of your basement ceiling perpendicular to the joists, spaced 16 inches on center. Buy enough clips to support each channel strip where it intersects each joist.

Screws

• 3/4-inch drywall screws;
• 1-5/8-inch drywall screws;
• 2-1/2-inch deck screws.

Gather These Tools

• Calking gun;
• Impact driver;
• Utility knife;
• Tape measure;
• Chop saw with metal cutting blade;
• Eye and hearing protection;
• Ladder;
• Long level or other straightedge.

How To Soundproof Your Basement Ceiling

Once you’ve gathered all the tools and materials, start soundproofing your basement ceiling. Here’s what to do:

• Seal all cracks in the subfloor: Use your ladder, calking gun and Green Glue to seal all cracks between sheets of subfloor of the rooms above your basement.
• Install first two layers of drywall: Use your tape measure, straightedge and utility knife to score and then cut sheets of drywall into strips of the correct width to fit snugly in all your joist cavities. Fasten the strips in place with an impact driver and drywall screws, then seal all cracks and seams with more Green Glue.
• Install insulation: Measure and cut strips of fiberglass or mineral wool insulation to fit snugly into all joist cavities. Hold each strip in place by fastening your 1-1/2- by 1-1/2-inch strips of wood to the inside face of each joist, flush with the bottom of the joists.
• Install hat channel clips: Mark lines on the joists with pencil every 16 inches. Use 1-5/8-inch drywall screws to fasten clips in place. Place one clip next to each line on all joists.
• Install hat channel: Custom-cut the strips of hat channel with the metal cutting chop saw to fit your ceiling space. (Don’t forget eye and hearing protection.) Secure the edges of the strips into the clips you’ve attached to the joists.
• Install final two layers of drywall: Cover the ceiling joists with a layer of 5/8-inch fire code drywall, using 3/4-inch drywall screws driven through the drywall and into the hat channel without touching the underlying joists. Seal all cracks and seams between sheets with more Green Glue. Install a second (fourth) layer of drywall with 1-5/8-inch drywall screws driven through both layers and into the hat channel strips. Offset the sheets so your seams don’t overlap with the seams of the first layer of drywall. Finish off with drywall tape and compound on all cracks and seams before applying paint.

Note: Wondering if four layers of drywall will decrease your basement ceiling height? Good question; you’ll only lose 5/8-inch.

The first two layers of drywall are inside the ceiling joist cavities, so no height is lost. The second two layers are surface mounted, leaving two sheets where there would normally be one. So the ceiling will be one drywall thickness (5/8 inch) lower than if there was only one layer.