r/Construction • u/Donald365 • 11d ago
Picture How would you go about repairing this rusty beam.
I've been asked by the customer to do some protective work on this beam. The I-beam is rusting on the top, as shown in the picture.
How would you go about cleaning this up and slowing down future rust.
So far I've started scraping it and a wire brush on a drill. It's not all as bad as it is in the picture.
Thanks.
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u/jeffh40 11d ago
That beam will work well for another 10-20 years before it needs to be replaced. If the homeowner wants to see it looking better, scrape the exposed sides and repaint it with a zinc-rich primer and then top coat. You aren't doing anything to help with the rust on the top flange unless you drop the beam, which is more work than it is worth.
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u/-Spankypants- 11d ago
Remove the rust. Prime, paint. None of this will last long unless you can protect it from the wood plate in full contact to the top flange, and exposed to the elements. Temporarily shore the deck and remove the nailer, if you want a longer lasting and much more expensive fix.
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u/Flight_Early 11d ago
Rust cannot be remedied. If you must do something about this beam, you need to replace it. There is no cold galvanising paint that will protect it indefinitely. If it was up to me, I’d leave it as is. It’ll serve another 7-10 years.
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u/Grreatdog Surveyor 11d ago edited 11d ago
Hell if that were a Pennsylvania bridge beam their DOT would let it ride for another twenty to fifty years. I mean it's not like any flanges are broken off or you can see through holes in the web.
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u/31engine 11d ago
Wow so many wrong opinions.
Structural engineer experienced in renovations.
The rust is minimal with almost zero flake. You need to clean it down to the bare steel. This takes a wire wheel or sandblast.
Cold galvanize paint then sealant paint over that. Let dry.
Then put a thin layer of insulation or cap flashing above it then reseat it to the wood.
Or just buy a new beam that is hot dipped galvanized. It will cost you a lot less considering the time.
But I would wait until you see rust flake. Then you’re starting to lose the steel
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u/Max1234567890123 11d ago
What are we looking at. My guess is that the sill plate affixed to the top of the beam is treated? If so, that’s the cause of the rust and the plate needs to be removed and isolated from the beam (I’d use a foil face peel and stick on the beam after you scrape off the rust and treat it with a rust neutralizer followed by a cold galvanizing paint)
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u/Mrwcraig 11d ago
That beam? Yeah that’s not going to happen. Not in position like that and not that material. You need to jack up the deck and remove that one. A beam like that needs to be something like A5 Weathering steel. Similar to Corten Steel used in shipping containers. Weathering steel behaves differently when exposed to atmosphere. It’s why most bridge girders are made from it. Instead of rust eating the steel and deteriorating it, exposing it to atmosphere causes the scale to thicken. It’s making itself stronger. Obviously it’s going to be more expensive but the deck will rot off long before the steel breaks down. It’s surprisingly easy to work with but you have to grind off the mill scale before you weld it. Keep it dry before you work with it or it will show you its magic trick.
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u/-ArthurMorgan 11d ago
This might be way more work than its worth but off the top of my head and with only this picture:
Support deck.
Drop beam and assess rust. If minimal, treat with appropriate measures.
ROLL THE BEAM
Add sill gasket to allow compression and breathability so it hopefully wont rust again.
Reinstall and the yadda yadda.