How to remove rust from external metal beam?

Question

Hi! I live in an elevated home and this area is outside my storage room, with my bedroom directly above it. The rust seems to be on the exposed metal beam/trimming under the roof area.

What would be the best way to:

* remove the rust properly
* stop it from coming back
* repaint/protect it for outdoors

Also if it helps, I live in Darwin where it is hot and humid during wet season. Thank you so much!

MitchellMc · Answer

Hi @anne15,

Just checking in to see how you ended up going with the rust repair. There were a few important things to work through there, particularly identifying where the moisture might be getting in from above before treating the beam itself.

Did you manage to inspect the roofing and start cleaning the rust back yet? And if you did move ahead with the repair, I’m sure others in similar humid climates would be interested to hear what products and approach worked best for you.

Hopefully it’s all coming together well, but if you hit any issues along the way or want a second opinion before repainting, we’d be more than happy to help further.

Mitchell

MitchellMc · Answer

Hi @anne15,

The first thing I’d point out is that, particularly in the first and second photos, there appears to be a fairly significant amount of rust concentrated along the top edge of the beam, with rust staining running down the face below it. That’s usually a good indicator that this isn’t just surface rust caused by Darwin’s humid conditions, but that water is likely getting in from above.

Before repairing the beam itself, I’d strongly recommend inspecting the roof sheeting and fixings in that area. My suspicion would be that a roofing screw seal or flashing has failed and is allowing water to track onto the beam. Unfortunately, unless the source of the moisture is addressed first, the rust is likely to continue returning even after repainting.

In terms of repairing the existing rust by removing all loose rust and flaking paint using either a wire brush, orbital sander or an angle grinder with a wire wheel attachment for heavier areas.

Pay particular attention to the larger rust patch shown in the first image, as well as all smaller rust spots along the beam.

Once you’ve cleaned it back to solid metal, apply a rust converter, a metal primer suitable for exterior use and then a quality exterior topcoat paint to seal and protect the steel.

Please also make sure to wear appropriate PPE while carrying out the work, including safety glasses, gloves and a dust mask or respirator, particularly if you’re sanding or using a wire wheel attachment, as rust particles and old paint dust can become airborne.

Please let me know if you have any questions.

Mitchell