Rust on Steel Joists
Rust on Steel Joists
(OP)
I am involved in a renovation project where a lot of the existing bar joists have some rust on them. The roof has a lot of leaks. It appears to mainly be surface rust and not to the point where it looks like the joists have been weakened. We are going to be replacing some but would like to try to keep as many as possible. What are my options with the rust? I am thinking about blasting in order to clean the rust off. It seems that would be cheaper than replacing a joist because it has some rust on it.
Thanks for your input.
I tried to attach a couple of pictures. Maybe it will work.
Thanks for your input.
I tried to attach a couple of pictures. Maybe it will work.






RE: Rust on Steel Joists
RE: Rust on Steel Joists
RE: Rust on Steel Joists
If you find lead, consider using dry ice blasting to keep down the quantity of contaminant. You'll have very little to dispose if you do this. If you use sand or abrasive grit, you'll pay a lot to dispose of all the contaminated sand.
Do some thickness testing on the deck to check its integrity. The "white rust" looks like it results from condensation. You might consider some mitigation for this as it will produce long term deterioration.
RE: Rust on Steel Joists
RE: Rust on Steel Joists
You should concentrate on ensuring that the roof doesn't leak anymore.
RE: Rust on Steel Joists
It was less expensive than I anticipated and the dry ice can be made on site.
It's also a lot less messy than water blasting.
RE: Rust on Steel Joists
hokie66:
Will it continue to rust if the existing rust is not removed?
I attached another picture. I have these joists marked to be replaced. They don't look like they have any section loss but they are rusted pretty bad. Any thoughts?
RE: Rust on Steel Joists
If you do feel you must replace the joists, is it not a better option to sister joists with additional ones and keep the old ones. (or that is what you meant)
RE: Rust on Steel Joists
One thing you might check though...if you're in a higher wind area, many times older joists were not checked for uplift, so lateral bracing and 1st diagonal should be checked. With small "wiggle bar" joists, the buckling in the first diagonal can be a problem under load reversal.
RE: Rust on Steel Joists
RE: Rust on Steel Joists
The joists are strong. The roof currently holds about 4" of water when it rains. It looks like a big lake up there. I found two joists that were damaged due to the extra weight. I will be able to look closer when they get the deck off.
I don't know a great deal about rust. They are building a new roof with a proper slope. The joists will be dry and in a low humidity environment. Will this stop the joists from rusting further? My concern is that I don't want the joists to continue to rust and lose strength. I have read about rust converters that basically sound like they seal the rust to keep out moisture and oxygen. It would go on like paint.
Thanks for all your input.
RE: Rust on Steel Joists