Step 1
Remove all furniture, wall hangings and window coverings from the room. Lay tarps over the floors to protect them from scratches, debris and damage. Remove window, door and baseboard moldings with a flat pry bar and set them aside for reinstallation.
Step 2
Turn off the electrical power to the room. Remove the electrical receptacle and light switch boxes with a screwdriver. Install extender boxes that are large enough to accommodate the second layer of drywall so they sit flush with the existing wall. Turn on the power on the room.
Step 3
Measure and mark obstacles on the new drywall panel, such as electrical outlets, light switches or windows, with a pencil. Cut these areas out with a drywall saw.
Step 4
Cut the tip off a tube of green glue with a utility knife and puncture the inner protective skin with a sharp nail. Load a caulking gun with the green glue.
Step 5
Lay the drywall on the floor or across two sawhorses.
Step 6
Run wavy lines of green glue over the back of the drywall panel, spaced every 4 inches, beginning 1 inch from the edge of the panel.
Step 7
Lift the drywall panel up against the existing drywall, beginning in a corner of the room, and press it in place. Have a helper hold the drywall to prevent it from falling. Move around the face of the drywall and press it against the existing drywall.
Step 8
Drive Type G screws through the drywall into the wall studs with a power screwdriver to secure it in place. Drive screws through the drywall every 16 to 18 inches along the wall studs to penetrate the studs by at least 7/8-inch.
Step 9
Create wavy lines over the next drywall panel with green glue. Lift the panel in place to tightly abutt it against the first panel then press it against the existing drywall. Drive Type G screws through the drywall into the wall studs every 16 to 18 inches. Continue to glue each drywall panel in place and secure each one with Type G screws until the second layer of drywall covers all of the walls in the room.
Step 10
Scoop up drywall joint compound on a drywall knife and fill in the gaps between drywall panels. Place self-sticking drywall tape over the joint compound. Add a thin layer of joint compound over the tape and let it dry. Sand the joint compound smooth with 220-grit sandpaper wrapped around a sanding block.