Rusting steel posts

Wondering if anyone can help. I have steel posts and plates supporting my house and deck. Some began to develop rust, some much worse than others. Got someone to treat them but now the rust is coming through again and I have found out they didn't do it right.

Here is what they did. First they wire brushed. Then they applied rust converter. Then they left it for about a month during which time it was exposed to the elements, including rain. After that they applied penetrol. Left it for another month and penetrol started peeling. Sprayed penetrol again. A month later came back and sprayed Cold Gal. Said they would be back to paint but never came. Now it's been 5 months since the process started and the rust is back, even flaking off in some parts.

Can anyone help with options from here? I called the Cold Gal manufacturer who said Cold Gal should only be sprayed on bare metal, not over penetrol or rust converter. They said if the condition of the cold gal is good still then just penetrol again and then paint. But I am wondering if I need to somehow remove the Cold Gal and start from scratch to actually stop the rust.

Also I live near the coast so the air is salty.

I don't have photos of all the posts before the work was done, only the worst ones. A few were very bad but the rest were only had surface rust. Now the posts that were very bad are beginning to flake. The ones that had only surface rust are again showing surface rust.

I would be grateful for any suggestions on how to rectify this!

You need good surface prep. You can’t paint rust and rust converter is useless in corrosive environments. Look up the data sheet for Dulux zincanode 402. Then get a mobile sand blaster or at least use a needle scaler with compressed air. Close to ground you could use a polyurethane waterproofing membrane over 2 coats of Zincanode. Best option is to look up someone who does industrial coatings.

Thanks Pulse 🙏. When you say look up someone who does industrial coatings, could you please give more info on the type of business you mean? Do you mean industrial painters? I live in the Tweed Shire in Northern NSW

https://sodatec.com.au/soda-blasting-tweed-heads/

this looks perfect, then get some good quality epoxy primer.

Thanks for the link 😊

Hey, I've got a similar issue (probably worse) in Perth. Did you fix yours? What approach did you take?

I still haven't had it fixed 🙁Had a few interruptions and waiting for a painter ... 2 quotes so far. One for 2 pack paint and the other for applying 2 coats penetrol and one coat epoxy.

Interesting. Thanks. I've written today to a guy in Perth that does mobile sandblasting and application of rust inhibiting coating - I'd then paint over myself with some sort of epoxy enamel in the colour we want. I've asked the sandblast / steel repair guy whether for me the penetrol route is really going to help rather than cleaning up the steel surface more actively.
I've got similar issue to you with steel support posts for a deck that sits at second storey height - lines up with our living space on second storey.

Don't know if I'm going down the right road but I'll let you know if the sandblasting guy gets back to me and if progress is made.

Hi Tsfreo, I've just had mine done. The painter ground away all the rust using a Josco 125 or 127mm wire wheel brush? It was a difficult job and he mentioned that a sandblaster would probably be better (they do make a mess though he said). But he did a great job and got all the rust off which is important. He did a coat of Penetrol, then a coat of Cold Gal and then 2 coats of Rust Guard Epoxy Enamel topcoat. The soil around your posts looks like it will continue to cause a problem with rust. You need to dig down to find the concrete footing. What happens from there depends on how bad the rust is. You might need to create a concrete footing if there isn't one? if it's rusted through you might need to replace the rusted section of the post? It sounds like you're in Perth and I'm on the east coast, otherwise I'd recommend the painter i hired.

Thanks for the update. I had a few people look at mine and conclude that I am too close to a neighbour to sandblast (because of mess). Without sandblasting the problem most likely to keep coming back for me. So, in the end, I am going to replace my four deck support posts. Custom made steel posts, galvanised and set in proper concrete footings. Is going to cost thousands, but is the proper way to fix them more permanently in the situation I am in. Of course, actually getting a final quote and commitment to do the job is proving hard. Huge tradie/build demand in the West.

That sounds like the best way to go if you want to resolve the problem and not have ongoing issues. I have some galvanized steel on my house already rusting - was probably made in China.

Seriously I would go for the zinc anode primer and wire brush. Hard to reach places can be done with a hand held sandblaster. It's not a huge mess at all. You could even drill a hole in each post and use rust converter as a spray inside the post. Get another 25 years out of those posts.

Fair enough. I've dug out two of mine that were not set in proper footings and they are in very bad condition below. Plus the welds at the top of a couple are pretty shot. I may be going over the top, but my kids play on that balcony and I don't want to have to worry about it. Cheers

You are right. Sometimes peace of mind comes at a cost. Especially with kiddies.

I suggest you get advice from your local council building surveyor
That will need to be inspected by a structural engineer.

Yep. Have a builder doing it. Not doing it myself.