Rusty rsj

[evanthorncliffe]

Hi, I know very little about construction so any advice would be appreciated. My plasterers have uncovered an rsj supporting the first floor internal wall and the rsj is showing surface rust with a couple of patches of deeper rust caused by condensation. I have given it a brush with a wire brush and will use a drill with a wire attachment .It's not flaking ect . Can I treat with with rust converter x2 and red oxide x2 or is it a bigger problem and need replacing? They plan to stick the plasterboard on with moisture resistant foam. I will address the condensation problem. Any advice appreciated.

[nod]

It’s unlikely that it need replacing 

[Super_Paulie]

It's rusty, but I'd imagine that beam will still be doing it's job when all on here have departed this realm.

[Pocster]

Mine look pretty similar as exposed to the elements for a few yrs . Don’t worry about it 

[SteamyTea]

I have a vague memory that the steal used in RSJs is meant to get a coating of corrosion. It gets a thin layer of oxidation that creates a skin, which inhibits further oxidisation.

I may be wrong though.

Edited July 21 by SteamyTea

[saveasteading]

25 minutes ago, SteamyTea said:

meant to get a coating of corrosion. It gets a thin layer of oxidation that creates a skin

No. Rust can continue to form, deep in until failure.(except Corten, which is very different).

 

It would stop rusting though if the dampness is stopped.

However, as best practice, and to remove any concerns about  it , treat it as proposed.

Another option is bitumen paint. The advantage being applying it in tricky corners.  But stuff like plasterboard won't stick so well.

 

Do ensure that the source of dampness is permanently resolved. Any clues on that?

[evanthorncliffe]

8 minutes ago, saveasteading said:

No. Rust can continue to form, deep in until failure.(except Corten, which is very different).

 

It would stop rusting though if the dampness is stopped.

However, as best practice, and to remove any concerns about  it , treat it as proposed.

Another option is bitumen paint. The advantage being applying it in tricky corners.  But stuff like plasterboard won't stick so well.

 

Do ensure that the source of dampness is permanently resolved. Any clues on that?

Yes it's condensation, I'm going to improve ventilation and put a  dehumidifier extractor in the kitchen as well (I forget the name for it). Thanks I'll do as you say. I'm a bit of a worrier!!

[saveasteading]

1 minute ago, evanthorncliffe said:

I'm a bit of a worrier

Better than not thinking about it and keeping the problem.

Asking the right questions. Keep doing so of your builder and BH.

[Spinny]

We had the same with steels that had been in place about 42 years (see pics).

I had our structural engineer take a look, he gave them a good poke with a screw driver and said they should be fine for another 100 years, vigorous wire brush (as you propose) and treat. He suggested an intumescent coating paint, but when I got some delivered the skull and crossbones warnings all over the stuff made it seem you would die if you opened the can. So I went with vigourous wire brushing/drill attachment, then treatment with Neutrarust 661 (NATO approved rust convertor for use in ships, tanks etc - available on Amazon), then 2 coats of iron oxide paint. Photo shows the end result.

 

Builder showed zero interest in doing anything to the steels so I had to do it myself.

Edited July 21 by Spinny

[SteamyTea]

1 hour ago, saveasteading said:

except Corten

May have been that I was thinking of.

CORTEN is a trade name made from Corrosion and Tensile.

 

A quick search showed that even CORTEN is affected by a 'wrong atmoshpere'.  To dry, it does not create the crust, rain not acidic enough, not enough crust.  I suspect that either high or low levels of sunlight will also affect it (photoelectric effect).

 

 

[SteamyTea]

 

https://en.m.wikipedia.org/wiki/Passivation_(chemistry)

[saveasteading]

1 hour ago, Spinny said:

He suggested an intumescent coating paint, but 

That is for fire, not corrosion although it would have the secondary benefit.

The  coats of intumescent paint that expand in heat absorb moisture. The top coat seals it.

So for just corrosion don't use intumescent.

@spinny a fire under these unprotected beams might destroy the house, but such an event is unlikely.

 

[evanthorncliffe]

Thanks for everyone's replies. It's put my mind at rest. I'll treat as described and deal with the condensation issue. It's  a 19th century midterrace with double glazing and painted exterior brickwork. It also had bitumen coated on the inside of the roof slates when I first moved in so the was very humid. I've replaced the roof and have felt under slates now so it can breathe now.

[SteamyTea]

2 hours ago, evanthorncliffe said:

It also had bitumen coated on the inside of the roof slates when I first moved in so the was very humid. I've replaced the roof and have felt under slates now so it can breathe now.

Would it not have been easier to fit a ventilation fan?

[Spinny]

5 hours ago, saveasteading said:

That is for fire, not corrosion although it would have the secondary benefit.

The  coats of intumescent paint that expand in heat absorb moisture. The top coat seals it.

So for just corrosion don't use intumescent.

@spinny a fire under these unprotected beams might destroy the house, but such an event is unlikely.

 

Your comment made me check - My mistake apologies, I was misremembering from 2 years ago...

 

Structural Engineer did NOT recommend intumescent - he actually recommended Zinc Phosphate Epoxy and I bought some from here https://www.taindustrialpaints.co.uk/products/two-pack-epoxy-high-build-zinc-phosphate-metal-primer - it is two part and you have to mix in a catalyst. When it arrived it had loads of health and safety and storage requirements so I didn't use it, and went with the red oxide.

 

[SteamyTea]

5 minutes ago, Spinny said:

When it arrived it had loads of health and safety and storage requirements so I didn't use it

Try this if you want something really lethal.

 

https://dhmo.org/facts.html

[Spinny]

5 minutes ago, SteamyTea said:

Try this if you want something really lethal.

 

https://dhmo.org/facts.html

Strewth.

They are going to kill us all for dollar...

 

https://www.youtube.com/watch?v=SC2eSujzrUY
 

[Nickfromwales]

6 hours ago, evanthorncliffe said:

Thanks for everyone's replies. It's put my mind at rest. I'll treat as described and deal with the condensation issue. It's  a 19th century midterrace with double glazing and painted exterior brickwork. It also had bitumen coated on the inside of the roof slates when I first moved in so the was very humid. I've replaced the roof and have felt under slates now so it can breathe now.

These sound like a huge step towards managing the trapped humidity, but also via extraction fans where you know you're getting unwanted levels. 

 

The rust on that steel is zero problem, seen way worse than that and they've been in for a half century! Scrub, apply the rust convertor, and live a long happy life.