Cellular shades have a honeycomb construction that reduces heat loss through the window and provides ultra-violet protection. Treat top-down, bottom-up shades as two blinds, one above the other. They have separate cords and controls for the top and bottom sections, so you can raise and lower them independently. If the strings for one or both sections tangle or break, you can restring them yourself to save money.
Things You'll Need
Plastic washers, one for each cord
Remove the shades from the window. Lay them on a clean work surface in the closed position with the top rail facing away from you. Open the top section slightly so you can locate the middle rail, which is the bottom rail of the top section and the top rail of the bottom section. The middle rail, also called the floating rail, contains an aluminum stiffener to identify it.
Remove the cord locks from both sides of the top rail. The cord lock on the left holds the cords for the top section and the cord lock on the right holds the cords for the bottom section. Slide the top rail to one side.
Cut the cords that finish at the floating rail and remove them. Measure and cut new cords for this section. Cut each cord to a length equal to twice the height of the fully open top section plus the width of the blind, plus 12 inches. Thread one end of the first cord through the restring needle and tie a washer to the other end. Push the needle through the first hole in the floating rail and thread it from bottom to top of the top section and out through the top stiffened bar, drawing the cord behind it. Repeat for all the cords in the top section. Pull the top ends of the cords so the washers lie flat against the floating rail. Tie a colored thread to the top of each cord for identification.
Remove the end caps from the bottom rail and slide the rail to one side. Locate the lowest pleat, which contains an aluminum stiffener. Cut the cords that finish at the lowest pleat and remove them. Measure and cut new cords for the bottom section. Cut each cord to a length equal to twice the height of the fully open blind plus the width of the blind, plus 12 inches. Thread one end of the first cord through the restring needle and tie a washer to the other end. Push the needle through the first hole in the lowest pleat, through the stiffener, and draw it through the blind until it emerges through the top edge of the floating rail. Repeat for all the cords in the lower section.
Thread the first cord of the bottom section into the restring needle again and draw the cord through the holes in the upper section and out through the top stiffened bar. Repeat for the rest of the cords from the bottom section and then pull the top ends of the cords so the washers lie flat against the bottom pleat. Slide the bottom rail onto the bottom cell containing the stiffened strip. Replace the end caps on the bottom rail.
Hold the cords with the colored thread attached in your left hand and the rest of the cords in your right hand. Ensure the cords are not twisted or tangled around each other. Take the cords in your left hand and lay them on top of the top stiffened bar, through the left cord guides and across to the left edge of the fabric. Take the cords in your right hand and lay them on top of the stiffened bar, through the right cord guides and across to the right edge of the fabric. Remove the colored threads.
Slide the top rail onto the top cell and stiffened strip, being careful not to catch or tangle the cords. Maintain a slight tension on the cords as you slide the top rail into place. Thread the left-hand cords into the left cord lock. Insert the cords through the balls and out the bottom of the cord lock. Repeat with the right-hand cords and the right cord lock.
Replace the cord locks on each end of the top rail. Hang the shade on the installation brackets and tighten the screws carefully.
Work slowly and methodically to ensure the cords don't get tangled.