How to Install Crown Molding to Cover Truss Uplifts

Place a ladder against the wall to give you access to the junction of the ceiling and wall. Measure the width of the walls you'll be installing the crown molding to.

Cut your crown molding to length. Use a miter box to cut the ends of the crown molding to the appropriate angles if you're joining the crown molding at corners.

Run a stud finder along the ceiling where it intersects with the wall and mark the location of the ceiling joist onto the ceiling with a pencil.

Place your crown molding against the wall and ceiling junction. Nail the crown molding into the marked locations for the ceiling joists with 6d nails. Don't nail the crown molding to the wall -- otherwise it won't move with the ceiling as the trusses raise and lower.

Counter-sink the nail heads with a nail set and hammer. Fill the depressions with wood filler and sand smooth when dry. Paint the crown molding, being careful not to paint the wall.