The strap (or "cord") is perhaps the most wearable component of a manual roller shutter. After years of daily use, it frays, wears thin and eventually snaps - leaving the shutter trapped in whatever position it was in.
The good news: replacing the strap is one of the few shutter repairs you can do yourself, even without much technical experience. You don’t need to pay €40 or €50 to a tradesman for something so straightforward. Put on some old clothes, grab your tools and let’s fix it!
Before you start, gather the following:
Buy a strap of the same width (14 mm or 22 mm - measure the old one before going to the shop). Sold by the metre at any hardware or paint store. You’ll typically need around 4 to 5 metres for a standard balcony door - get 50 cm more than you think. Colours are usually grey, beige or white.
Phillips screwdriver (or flathead, depending on cover screws), scissors or a sharp knife, lighter or candle (to seal the cut ends so they don't fray).
Allow 30–45 minutes if it’s your first time. An experienced technician does it in 10–15 minutes. You’ll also need a ladder to reach the upper shutter box.
Follow these steps in order. Don't rush - your safety comes first.
If the strap hasn't snapped completely yet, lower the shutter all the way down. This unloads the drum spring, making the job safer. If the strap has already broken, the shutter will already be down (if it was released).
Find and remove the screws or clips holding the cover on the interior side (above the window). Keep the screws in a cup. You can now see the drum (the cylinder around which the strap winds).
On the drum you'll see a small slot or clamp holding the strap. Pull it out or unscrew it; remove the old strap entirely. Keep it as a length reference. Next, go to the lower wall and unscrew the strap winder box (the casing that collects the strap). ⚠️ Caution: Inside there is a metal wheel with a very strong spring. If it's still wound up, hold the wheel firmly with one hand and let the spring unwind slowly and in a controlled manner.
Cut the new strap to the correct length (measure the old one + 10 cm extra). Seal the ends with the lighter. Thread one end into the winder box, tie it to the wheel and wind the mechanism (turn the wheel in reverse until the spring tightens). Then take the other end, thread it through the guide rollers and tie it to the upper pulley (inside the box) exactly where the old one was. ⚡ Pull the strap so it sits relatively taut between the upper pulley and the lower winder.
Manually wind the strap around the drum 2-3 times. Close the cover temporarily and test: pull the strap to raise the shutter, let it return. If it operates smoothly, screw the cover on permanently.
Strap replacement is a simple job, but a few points can trip you up:
If you buy the wrong width, it won't fit through the wall slot or onto the drum. ALWAYS measure the old strap before buying.
If you haven't fully lowered the shutter, the drum may be under spring tension. If released, it can spin violently and injure fingers or damage the shutter.
If the strap is too short, the shutter won't lower fully. Always leave 10-15 cm extra length for wrapping on the drum.
A fabric strap frays immediately if you don't seal the cut ends. Use a lighter to gently melt the fibres together.
💡 Tip: If the strap keeps snapping every 2-3 years, the drum or guide rail is probably wearing it. Consider upgrading to a motorised system - the investment pays off over time.
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