Aluzinc sheet that has rusted

[mickeolsson]

Hello. On our house, we have a dormer with a balcony on the upper floor. The balcony has aluminum-zinc sheet metal on the floor. A few years ago, we laid roofing felt+decking here and installed a glass railing. We have now noticed that in some places the sheet metal has developed superficial rust/oxidation. We have now removed the glass railing and decking to redo it. Do you have any tips on how we can redo this without having the same problem? Removing the sheet metal would involve a major project (it goes behind the facade) and would be very expensive, so we want to avoid that completely. Some thoughts we have... sanding off the rust, painting with anti-corrosion paint+topcoat? Burning roofing felt over the entire area? After that, we need a new solution and without pressure-treated decking, which we suspect is part of the problem (we've been told aluminum-zinc and pressure-treated don't go well together). Composite decking is one thought. Any tips?


Best regards/Mikael

 

[Violina]

The problem is probably that the decking has rubbed off the surface treatment..

 

[plåtrickard]

The problem is probably that the decking has rubbed off the surface treatment..

No, the problem is that aluzink is a crappy material that barely works with itself.. I've seen several such examples like ts but worse.. It doesn't get along with plaster, pressure-treated wood...

 

[plåtrickard]

 

[mickeolsson]

Thank you for your response, Rickard. Rickard, do you have any tips on what we can do? I would prefer not to tear everything down.

 

[Kane]

[image]

You can't see in the image what the different symbols in the chart mean.

 

[plåtrickard]

Thank you for your response, Rickard. Rickard, do you have any tips on what we can do? I'd rather not tear everything down.

Unfortunately not, other than definitely not sanding aggressively, the sheet metal is only 0.6mm thick.
How old is the roof? I would probably recommend lead oxide on the rust, a good primer on the entire roof, and two coats of finish paint. If you then want to have decking again, use solar panel seam mounts and build from them, to avoid direct contact again.
But I don't know what the manufacturer recommends in such cases.

 

[plåtrickard]

You can't see in the picture what the different symbols in the table mean.

New attempt..

 

[mickeolsson]

I see in the table that papp can be a problem. We had placed papp between sheet metal and studs to lift a bit from the metal and avoid direct contact. It was where it was the worst, seems like papp we cannot have.

 

[mickeolsson]

Unfortunately not, other than definitely not sanding aggressively, the sheet metal is only 0.6mm thick. How old is the roof? I would probably recommend lead primer on the rust, a good primer on the entire roof, and two coats of finish paint. If you then want decking again, use solar panel seam mounts and build from there, so there's no direct contact again. But I don't know what the manufacturer recommends in such cases

The roof is about 7 years old. The decking is about 5 years old. Good tip with the seam mounts, I'll look into that.

 

[mickeolsson]

New attempt.. [image]

I am investigating painting options, but if we have to replace the metal, which metal would you recommend that is durable and preferably similar to Aluzinc?

 

[plåtrickard]

Zinc magnesium (but how it will be in 10 years, I don't know...) is supposed to replace aluzinc type..
Or regular coated sheet metal, silver metallic is available.

 

[plåtrickard]

Pure Aluminum is quite popular on the west coast I know.. However, not so familiar with it

 

[mickeolsson]

Ren Aluminium is quite popular on the west coast I know.. However, I'm not very familiar with it

Thanks for all the input. We are also considering tearing off the sheet metal and going with papp to avoid worrying about similar problems in the future.