Fill the hopper of your spray rig with loose, spray insulation fibers and binder as per the manufacturer's instructions. Enter the attic area dragging the nozzle of the spray hose with you. Spray the insulation in a sideways motion to coat the inside of the roof with the fibers.
Unroll pieces of R-19 insulation. Lay a strip of roll insulation in the space between each rafter with the paper side face-up. Cut the insulation with shears to fit.
Mix a cap full of bleach to 2 gallons of water in a plastic bucket. Dip a rag into the bucket and wring it out so that it will not drip. Wipe the ceiling with the bleach water-soaked rag to kill any mold or mildew present. Wait for an hour then wipe the ceiling with clean, dry rags to remove any remaining moisture.
Squeeze the trigger of your caulk gun loaded with construction adhesive and drag the tip of the tube across the back of a piece of foam panel insulation. Apply several beads of adhesive to the back of each panel then press them onto the ceiling. Cut the foam insulation panels with a utility knife as necessary. Cover the entire ceiling with the panels.
Cover the foam panels on the ceiling with 1/4-inch drywall. Drive drywall screws through the drywall, then the foam and into the existing ceiling. Countersink each of the screw heads with a power drill. Cover the seams between the boards with self-adhesive mesh tape. Cover the screw heads and mesh tape with drywall compound. Let the compound dry overnight then sand each seam and screw head smooth.