A New Garage Door

How to choose the right spring size for your garage door

Garage door springs carry the weight of the door and control its balance. An undersized spring makes the opener work harder, accelerates cable wear, and may leave the door unable to close properly. An oversized spring can create the same balance problems while placing unnecessary stress on the opener, tracks, and frame.

Choosing the right spring size starts with the complete door system rather than the visible panel dimensions. Two doors of the same width and height can weigh different amounts because of insulation, windows, steel thickness, and hardware. The spring must match the door’s weight, lift, track arrangement, and shaft.

Australian properties add several practical considerations. Sectional doors are common in Sydney, Melbourne, and Brisbane apartments, while roller doors remain popular in suburban and regional garages. Metric hardware is standard, yet some spring charts still use imperial lift ratings. Wind-rated retention systems are particularly important in cyclone-prone areas of north Queensland.

Use the process below to identify the system, check the numbers, compare suitable options, and avoid guesswork. Spring replacement is high-risk work because torsion and extension springs store substantial energy. Selection can be done carefully, but installation and adjustment should be left to a qualified technician.

Identify the spring system and door weight

A torsion-spring garage door has one or two springs mounted horizontally above the opening. Their winding cones fit onto a torsion shaft connected to the cable drums. An extension-spring door has springs attached between the lower part of the door and brackets near the header, often working through cables and pulleys. Identifying the correct type prevents an incompatible replacement.

The most useful starting point is the door’s actual weight. Check the specification label, instruction manual, or original sales documentation for the model. If those records are unavailable, have the door weighed or ask the manufacturer to confirm the weight for its exact configuration. A calculation based only on area and panel type is an estimate and can be wrong by enough to cause a serious balance problem.

Also record the door’s width, height, number of panels, track style, and lift arrangement. Insulation, windows, reinforcement, and heavier hardware all affect the operating load. Note whether the torsion shaft is solid or hollow, the cable-drum diameter, and whether the existing installation uses standard, high-lift, or low-headroom tracks.

Match the spring type to the door design

For a torsion system, spring selection considers total door weight, lift, IPPT rating, spring wire diameter, installed length, winding-cone size, shaft length, and the number of winding turns allowed. IPPT means inches per pound of torque and describes the lift the spring is designed to produce under load. A spring with the correct weight capacity can still operate poorly if its lift characteristics do not suit the tracks.

Extension springs are selected from a different chart based on door weight, spring capacity, and the cable or pulley arrangement. They normally work as a matched pair, and the chart may specify capacity for the complete door rather than for one spring. A replacement spring should also match the original spring length and hook or eye dimensions so the existing hardware remains correctly aligned.

The lift and track configuration cannot be changed simply by fitting a different spring. Standard-lift, high-lift, and low-headroom systems place the cable drums at different heights and use different spring geometry. Wind load is another separate issue: a stronger lifting spring does not replace wind-rated guide hardware, retention struts, or structural anchoring.

Read spring sizing charts correctly

Begin with the confirmed door weight and the manufacturer’s chart for the matching spring type and lift system. For torsion springs, the chart may show the required IPPT, wire size, length range, and allowable turns. If two springs are used, follow the chart’s instructions for dividing the load instead of assuming that any equal split is suitable. Match the drum, cone, shaft, and hardware dimensions as well.

Charts supplied with North American torsion springs commonly use pounds and inches. Australian doors are usually specified in kilograms and millimetres. You can convert door weight from kilograms to pounds and physical measurements from millimetres to inches to interpret an imperial chart, but the IPPT rating must remain in the chart’s stated units. Confirm that an equivalent metric spring is approved for the door before ordering it.

Several common errors produce unstable doors. Selecting the strongest available spring increases opener strain and can damage cables or hinges, while a weak spring leaves the motor fighting the door’s weight. Copying the label from an old spring may reproduce an incorrect specification, and stretching or modifying a spring to make it fit changes its operating characteristics. If a spring has broken, the correct replacement should still be selected from the door’s weight and configuration rather than from the failed part alone.

Account for Australian conditions and usage

Wind performance matters in regions where cyclones, strong winds, or sudden gusts can affect the garage. Australian garage doors are commonly considered under wind-load regions, with the required category depending on the installation location and exposure. Ask the supplier to document compliance with the current applicable Australian garage-door and wind-load standards, such as the relevant AS 1906 requirements, and confirm which retention hardware is approved for the site.

Climate can shorten the life of springs and related hardware. Salt-laden air around coastal areas of Queensland, New South Wales, and Western Australia can accelerate corrosion at winding cones, brackets, cables, and hinges. Hot, dry conditions in Perth and inland Australia also subject metal components to large daily temperature changes. Galvanised or corrosion-resistant finishes, sealed bearings, and suitable lubricants help protect the system, but the correct spring remains the foundation of reliable operation.

Local door preferences also affect the calculation. Apartment garages in inner Sydney, Melbourne, and Brisbane frequently use sectional doors with several insulated panels, while standard roller doors remain common on detached homes. A replacement door assembled for a local market may use different steel gauges, window sections, or reinforcing struts from the original model. Check the complete door specification rather than relying on its nominal size.

Make a safe final decision

Before ordering, compare the measured information with an approved spring chart and the door manufacturer’s parts list. Use this practical checklist:

A correctly selected spring should allow the door to remain balanced at normal stopping points and move smoothly without heavy opener effort. It should not force the opener to lift the entire weight, slam into the floor, drift, or remain uneven. If a new spring behaves this way, the issue may be incorrect installation, an unbalanced door, damaged tracks, or a different door weight rather than the spring itself.

Before ordering a replacement, gather the door model, measured weight, spring type, lift arrangement, drum diameter, and clear photographs of the complete system. Pro Support B.V., based in Hengelo, Netherlands, offers practical garage-door guidance and company contact details for checking these requirements. Contact Pro Support B.V. through its website with the recorded specifications to identify a compatible spring and arrange safe installation without unnecessary trial and error.