How to Soundproof a Door

How to Add a Soundproofing Blanket

Sound passes through doors of inadequate mass, especially hollow-core interior doors. The solution is to add a layer of dense mass on the interior side of the door.

Soundproofing or sound absorption blankets are long woven mesh fabric sheets that are specifically for soundproofing walls and doors. The blankets hang from grommets or hooks that allow the blankets to be removed and replaced.

1. Measure Hole Spacing

   Measure the distance between the holes at the top of the soundproofing blanket.

2. Transfer the Measurements to the Door

   Lay the tape measure across the top of the door and transfer the hole spacing to the door. To keep the holes level, use a bubble level. Mark with a pencil.

3. Drill Holes

   Drill holes in the door at the marked locations. Use a drill bit size specified by the blanket hanging kit.

4. Add the Wall Hangers

   Gently tap the hangers into the wall or door.

5. Install the Soundproofing Blanket

   Screw the grommets into the holes while holding the soundproofing blanket in place.

   Attaching the blanket to the door with hook-and-loop tape is another option. A combination of a blanket and sealing will most likely give you the best results.

How to Seal the Gaps Around the Door

Doors are surrounded by gaps, plus there are hidden gaps behind the door trim. Sound passes through gaps. The solution is to fill these gaps.

Seal the gaps around the door with a door sweep on the bottom and weatherstripping at the top and the sides. Extra door soundproofing can be achieved by removing the door trim and filling in the gaps with caulk or insulating foam.

1. Add Weatherstripping

   Cut three lengths of foam or rubber weatherstripping with scissors or a utility knife: two for the sides and one across the top. With the door open, remove the protective covers from the backs of the weatherstripping. Apply the weatherstripping on the inside of the door trim.

2. Add a Door Sweep to the Bottom

   Screw a rubber, vinyl, or neoprene door sweep to the bottom of the door. The door sweep may attach to the interior side of the door at the bottom. Other door sweeps slip under the bottom edge of the door.
   

   Tip

   For perfectly airtight door bottom sealing, install an automatic door bottom. This $200 to $250 device lowers a neoprene seal to the floor when the door is closed. It automatically raises when you open the door.

3. Seal the Inner Door Frame (Optional)

   Pry off the door trim. Squeeze caulk or low-expansion insulating foam in the gap between the door frame and the door header on top and between the door frame and the two-by-four studs on the sides. Replace the trim with finish nails or a power nailer.
   

How to Install a Solid Core Door

Sound passes freely through hollow-core doors. Hollow-core interior doors, standard in many houses, are made of thin pressed wood and honeycomb cardboard spacers. The solution is to replace a hollow-core door with a solid-core interior door.

Replacing a hollow-core door with a solid mineral core door boosts sound absorption by about 37 percent.A standard interior wall with two sheets of drywall, studs, and no insulation has a sound rating of STC 36. Installing a particleboard or mineral core solid core door makes the door comparable to walls.

1. Order the Door Slab

   Order or purchase a stock solid core door slab based on the measurements of the existing door.

2. Remove the Existing Door

   Remove the existing door by unscrewing the hinges from the door and the door frame.

3. Mark New Hinge Locations

   Hold the old door and the new door on the edge, side by side. Clamp them together. The hinge edge should point up. Use the old door's hinge locations to mark the locations of the hinges on the new door.

4. Mortise the New Hinges

   Cut out the locations for the hinges on the solid core door with the hammer and chisel. Chisel carefully to avoid cutting too deeply into the material. The tops of the hinges should be flush with the edge of the door.

5. Install the New Hinges

   Screw the new hinges into place in the mortises.

6. Install the New Door

   Lift the door into place and screw the hinges into the existing hinge screw holes on the door frame. Have an assistant help with this step because solid-core doors are heavy.

How to Add an Acoustic Door Panel

Sound transmits directly through the faces of interior or exterior doors. Acoustic or soundproofing door panels are a solution when soundproofing blankets are not an option. Soundproofing wall blankets hamper door access; acoustic door panels do not.

Acoustic door panels are sized to fit the door. Cut-outs and slits allow access to the door handle and the hinges. Acoustic door panels absorb some exterior sound but have more value in dampening in-room noise.

1. Dry-Fit the Door Panel

   Hold the acoustic door panel against the interior side of the door. Make sure that it is evenly spaced on all sides. Lightly mark the dimensions of the panel on the door.

2. Prepare the Adhesive

   Remove the protective cover from the adhesive backing. Some acoustic door panels may not have adhesive backing, requiring you to apply a separate adhesive.

3. Apply the Door Panel

   Apply the acoustic door panel to the door, remaining within the spacing lines marked earlier. Smooth out the panel by hand.

When to Hire a Professional

Installing a pre-hung solid core door (rather than a slab door or door blank) is a difficult process often best left in the hands of professional door installers. Professional-level door soundproofing for music studios or home theaters will need professional help from an audio consultant or sound control contractor.