A broken or detached rung on a steel fire escape ladder is a serious safety hazard that needs fixing promptly and correctly. While an experienced DIY welder can tackle this repair, the structural and life-safety nature of a fire escape means the work must meet a high standard — a poor weld here could cost lives. If you have any doubt about your welding ability, call a qualified tradesperson.
Understand the Safety Stakes First
Fire escape ladders are life-safety structures. Under the NZ Building Code, means of escape from fire must be maintained in a safe and functional condition. If your fire escape is on a commercial or multi-unit residential building, repairs may require a building consent or at minimum a record of the work — check with your local council before starting. For a private single dwelling, the repair is generally exempt from consent under Schedule 1, but always confirm with your council.
Before touching the ladder, take it out of service if at all possible. Cordon it off and put up a sign so nobody uses it while it's being repaired.
Assess the Damage
Before striking an arc, inspect the ladder carefully:
- Check the rung itself — is it cracked, bent, or just detached at the weld joint? A bent or cracked rung may need full replacement rather than re-welding.
- Check the stringers (side rails) — look for rust, cracks, or deformation around the rung socket or weld zone.
- Check for corrosion — surface rust is manageable, but deep pitting or section loss means the steel may be too compromised to weld safely. In that case, the whole ladder section may need replacing.
- Identify the steel grade — most NZ fire escape ladders are mild steel (typically Grade 250 or 350 to NZS 3404). If you're unsure, treat it as mild steel and use a compatible filler.
If the damage is extensive or you find significant corrosion, stop and call a structural engineer or experienced fabrication welder.
Tools and Materials You'll Need
- MIG welder (a 150–200A machine is suitable for most ladder steel) or stick (MMA) welder
- Angle grinder with flap disc and cutting disc
- Wire brush and rust converter if needed
- Welding helmet (auto-darkening recommended), gloves, leather apron, and steel-capped boots
- Clamps or magnetic squares to hold the rung in position
- ER70S-6 MIG wire (0.8 mm or 0.9 mm) or E6013/E7018 stick electrodes for mild steel
- Weld-through primer or cold galv spray for finishing
You can source welding consumables and PPE from Bunnings or Mitre 10.
Step-by-Step: Welding the Rung Back On
1. Prepare the Joint
Grind back the old weld material and any rust from both the rung end and the stringer socket until you have clean, shiny steel. Contamination is the enemy of a strong weld — paint, rust, and galvanising all cause porosity and weak joints. If the ladder is galvanised, grind the zinc coating back at least 25 mm from the weld zone and work in a well-ventilated area, as zinc fumes are toxic. Refer to WorkSafe NZ guidance on welding fumes before you start.
2. Position and Clamp the Rung
Offer the rung up to its original position. Use clamps and magnetic squares to hold it square and level. Double-check it's at the correct height and angle — rungs should be horizontal and evenly spaced (typically 250–300 mm apart on NZ fire escapes).
3. Tack Weld First
Place small tack welds at two or three points around the joint to lock the rung in position. Check alignment again before committing to full welds.
4. Run the Full Welds
Weld all the way around the joint (a full circumferential fillet weld if it's a round rung into a socket, or full perimeter welds if it's a flat bar into a notch). Aim for a fillet weld throat of at least 6 mm for typical ladder steel. Work in short passes and allow the steel to cool between runs to avoid distortion and heat-affected zone cracking.
- MIG settings: roughly 150–180A, 19–21V for 5–6 mm mild steel
- Stick: E7018 at around 120–140A for 3.2 mm rod
5. Inspect the Weld
Once cool, visually inspect for porosity, undercut, cracks, or incomplete fusion. Grind and re-weld any defects. For a critical life-safety repair, consider having the weld inspected by a qualified welding inspector or structural engineer.
6. Protect Against Corrosion
Apply a weld-through primer or cold galvanising compound to the bare steel, then finish with a suitable metal paint. Resene and Wattyl both offer metal primers and topcoats suitable for exterior steel.
Load Test Before Returning to Service
Once the paint is cured, apply a static load test — stand on the rung and apply your full body weight, then bounce gently. If anything moves, creaks, or feels wrong, take it out of service and re-inspect.
When to Call a Professional
Call a qualified tradesperson if:
- You are not an experienced welder — a poor weld on a life-safety structure is dangerous
- The ladder is on a commercial, industrial, or multi-unit building
- There is significant corrosion, cracking, or section loss in the stringers
- The ladder is galvanised and you're not set up to handle zinc fumes safely
- You need a structural engineer's sign-off for insurance or compliance purposes
A qualified fabrication welder or structural steel tradesperson can complete this repair correctly and provide documentation if required. You can find experienced local welders on tradedirectory.co.nz.
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