How to replace a roller shutter cord step by step

What you need

• PZ2 Pozidriv and flat screwdrivers
• Scissors or Stanley knife
• Lighter to seal the cord end
• Tape measure
• 3-step stepladder
• Needle-nose pliers to feed the cord through the groove
• Braided shutter cord, 4.5 mm or 6 mm, 5 or 10 m roll (Gaviota, Wolfpack, Micel, 3-6 €)
• Recessed or surface-mounted cord winder if the spring no longer tensions (Gaviota or Pujol, 8-14 €)
• New plastic cord guide if the current one is worn (2-3 €)
• For alicantinas: 6 mm polypropylene rope and a stainless steel cleat (3-5 €)

Step by step

1. 1

   Lower the shutter and measure the old cord

   Leave the shutter fully down. Measure the old cord's diameter with a ruler (4.5 or 6 mm) and the length you need: window height times two plus a metre spare. Take a photo of the cord's route inside the box before you take anything apart.

2. 2

   Remove the cord winder

   Take off the winder cover and loosen the two side screws. Ease it out slowly: the spring may still be loaded. Free the old cord from the groove in the reel and let the reel unwind completely by turning it with your finger.

3. 3

   Open the box and clean the pulley

   Remove the inspection lid of the shutter box (screws or push-fit). Find the cord pulley at the end of the axle, undo the old knot and pull the cord out. Vacuum the sand and dust from the pulley and from the cord guide opening.

4. 4

   Tie the new cord to the pulley

   Melt the end of the new cord, feed it through the hole or slot in the pulley with the pliers and tie a small double knot that does not stick out. Pull hard to check it does not slip.

5. 5

   Wind it on in the right direction

   With the shutter down, turn the pulley by hand and wind the cord on in the same direction as the old one, with the turns side by side and not crossing. Wind on the window height plus two turns: 5 or 6 for a 1.2 m window.

6. 6

   Feed the cord down to the winder

   Drop the free end down through the box opening, pass it through the cord guide in the wall and take it to the winder housing. Check it runs straight and does not rub on the edge of the box.

7. 7

   Tension the spring and fit the winder

   Hook the cord into the groove in the reel and turn in the direction of the arrow: 10 turns for a window, 14 for a balcony door. Hold the reel, seat the winder in its housing, screw it in and fit the cover.

8. 8

   Test and adjust

   Raise and lower the shutter three times. It should go up with a firm pull and stay at any height with the cord taken up. If the cord hangs loose, add two turns; if it pulls too hard, remove two. Cut off the excess leaving 10 cm and melt the end.

Before replacing a roller shutter cord: cord types and why it breaks

The cord on a boxed roller shutter is a braided polyester or polypropylene cord of 4.5 mm or 6 mm diameter. It works just like a flat strap: it winds onto the pulley on the axle when you raise the shutter, and a spring in the winder takes it up when you lower it. It is sold in 5 and 10 metre rolls at any ferretería (hardware shop) and at Leroy Merlin, Bricodepot or Bauhaus for 3-6 €. The cord winder is different from a strap winder: it has a narrow reel with a round groove, and comes in recessed and surface-mounted versions.

The alicantina blind, very common in village houses, penthouses and terraces in Alicante, Elche and the Vega Baja, has no box. It is a curtain of wooden or PVC slats joined by chain or cord that hangs on the outside, and you raise it by pulling a 5-6 mm cord that runs over a pulley at the top and ties off on a cleat (the double hook on the wall). Here the cord takes sun and rain all year and usually snaps at the point where it rubs on the pulley.

In both cases the cause is the same: wear where the cord rubs on the pulley or cord guide, fibres dried out by the sun and, on the coast, salt that crystallises inside the braid and cuts it from within. If the cord is stiff, faded or fuzzy, replace it before it snaps with the shutter half way up, which is exactly when the spring gives you a whiplash.

• 4.5 mm cord: light PVC shutters up to 1.2 m wide, small winder.
• 6 mm cord: aluminium shutters, balcony doors and wooden alicantinas.
• Outdoor polypropylene rope (alicantinas): stands up to rain and does not rot.

Mistakes we see when people replace a shutter cord

The most common slip is buying washing line or smooth nylon rope. It slips on the pulley, stretches, and within a few months the shutter no longer goes all the way up. You need proper braided shutter cord, which grips in the groove and does not give. We also see cords that are too thick to fit the winder and jam in the cord guide.

The second mistake is tensioning the winder spring wrongly. Too few turns and the cord hangs slack and jumps off the reel; too many and the spring snaps or the shutter stays up and will not come down. The reference we use: 10 turns for a 1.2 m window, 14 for a 2.2 m balcony door, then adjust two at a time after testing.

On alicantinas the classic error is tying the cord to the bottom slat with a knot that works loose. Use a bowline or pass it twice through the ring and finish with a double knot, then melt the end with a lighter. And do not forget the cleat: if it is rusted by salt air, replace it with a stainless steel one (3-5 €) or the new cord will chafe through in weeks.

When to call a professional

If you open the box and the pulley is broken, the axle wobbles or the cord winds outside the groove, the repair needs parts and tools you will not have at home. On alicantinas, if the top pulley is anchored in hollow brick and has pulled loose, it needs refixing with chemical anchor, and that is a job we do.

Replacing the cord and winder costs 40-70 € including materials and call-out, and takes 30-40 minutes. If the pulley or axle also needs replacing, the price rises to 80-150 €. The full table is in how much roller shutter repair costs and you can book through roller shutter repair. We arrive in 20-45 minutes in Valencia, Alicante, Torrevieja and Benidorm and in 30-60 in Dénia, Jávea, Calpe and Altea.

For alicantinas and village-style shutters we mostly work in Alicante and Elche, where more homes have this system.

Care on the coast: salt air, sun and damp

Outdoor cords on the seafront last 2 or 3 years at most. Once a year, wash the cord with fresh water and a sponge to remove crystallised salt and check the section that runs over the pulley: if you see cut fibres, replace it. Always choose polypropylene or polyester cord with UV treatment, never cotton, which rots in the night-time humidity of Torrevieja or Dénia.

The pulley on an alicantina is usually zamak or iron and seizes up with rust. A drop of sewing machine oil on the pulley axle every six months stops the cord rubbing hard. In the internal winders of boxed shutters, vacuum out the sand that gets in through the gaps and do not use grease: the spring must run dry.

Related guides

If your shutter uses a flat strap instead of a cord, follow how to replace a roller shutter strap. If the shutter has jumped out of its guides when you pulled the cord, read roller shutter dropped or off its track. And for a general run-through of faults, how to fix a roller shutter.