How to Mount Lights and Fittings on Corrugated Iron (Without the Wobble)
If you've ever tried to mount a sensor light, junction box or camera on a shed wall, you'll know the problem. Corrugated iron is all hills and valleys, and a flat fitting only touches the tops of the corrugations. Tighten the screws and the fitting rocks, twists or crushes the sheet — and there's nowhere neat to hide the cable.
Why flat fittings and corrugated iron don't get along
- Only a few contact points. A flat base sits on the crests, so it can pivot and work loose over time.
- Gaps behind the fitting. The valleys leave openings for water, wasps, geckos and dust to get in.
- Nowhere for the wiring. Cable either runs along the outside of the wall or through a hole that's hard to seal.
- Crushed sheeting. Over-tighten to stop the wobble and you dent the corrugations.
The usual workarounds
Most people cut a timber block to shape, pack the gaps with silicone, or make up a bracket. They work, but timber rots and stains Colorbond, silicone never looks tidy, and none of them give you a clean place to run the cable.
Meet CorroLock
We designed CorroLock to solve exactly this. It's a mounting block with a back shaped to the corrugated profile, so it sits flush on the sheet and locks across two corrugations. The front is a solid, flat face to screw your fitting to.
- Locks across 2 corrugations — it can't twist or slide once it's fixed.
- Hidden rear cable recess — room behind the face for wiring, connectors and resistors.
- Cable exit slot with a press-in blanking cap — run cable out the bottom, or cap it off for a clean finish. A cap comes with every block.
- Countersunk holes over the crests — fixed the same way roof screws are.
- Black, White or Grey — to suit your cladding.
Which size do you need?
Every CorroLock is 160 mm wide and 27 mm deep. Pick the height that suits your fitting:
| Size | Cable recess | Good for |
|---|---|---|
| 160 × 150 mm | 32 × 120 mm | Small lights, sensors and cameras |
| 160 × 200 mm | 32 × 170 mm | Floodlights and small junction boxes |
| 160 × 250 mm | 32 × 220 mm | Larger junction boxes and switches |
| 160 × 300 mm | 32 × 270 mm | Outlets, larger fittings and signs |
They come in 1, 2, 3 and 4 packs, and the price per block drops the more you buy.
Will it fit my wall?
CorroLock suits standard corrugated iron with crests about 76 mm apart and about 16–17 mm deep — that covers Custom Orb, Stramit Corrugated, Wallclad and similar 762 mm cover sheets. Measure from the top of one corrugation to the top of the next to check. If your shed is Trimdek, Spandek or Klip-Lok, send us a message about versions for those profiles.
How to install it
- Sit the block over two corrugations where you want the fitting, with the cable slot facing down.
- Mark the 4 screw holes and, if you're bringing cable through the wall, your cable entry inside the recess area.
- Drill the cable entry through the sheet inside the recess — it stays hidden behind the block.
- Fix with 4 × 10g roofing screws with sealing washers, into a girt or frame behind the sheet where possible.
- Mount your fitting to the flat face, then run cable out the slot or press in the blanking cap.
Fixed electrical wiring must be installed by a licensed electrician.
Designed and made in Far North Queensland
CorroLock is designed and 3D printed by us at FNQ Industrial 3D in Far North Queensland. Need a different size? Send us a message — we're always happy to talk custom jobs.
