Treatment for rusted exposed RSJ ?

[Lower]

That steel looks like it is delaminating. I have only seen that happen on poor quality steel, either very old, or the Russian stuff that Italy used to make cars out of.

It looks like it has lost structural integrity.

That’s spalling rather than delamination. It’s quite badly rusted.

 

[cdbe]

I would be having a serious go at that, probably scaff tower and angle grinder (with a proper grinding disc) - back to clean bright metal and see what's left. I wouldn't be worried about it failing (unless half of it's gone under the rust) because it's right at end of the beam but still need proper attention. Looks like water getting inside the pillar as well - signs of blown render.

 

[borisbathtime]

That’s spalling rather than delamination. It’s quite badly rusted.

I think what you see as delaminating or spalling is mostly the large amount of direct to rust paint and wax oil I put on last year without grinding it down - the beam underneath has a lot of surface rust and a little spalling but is not delaminating ..…..yet !

 

[ajstoneservices]

Anyone thinking of touching that with an angle grinder is off their trolley.

 

[borisbathtime]

Ok so initial clean with vibrating hand tool looks ok - there was some delaminating on the bottom horizontal of the beam and that section has maybe lost a quarter of its thickness - vertical section and top horizontal seem to have remained original thickness. Will get a knotted wire brush on it next and try to get more bare metal before a coat of neutrarust 661 as suggested.

 

[cdbe]

Still looks far too rusty to me. Get that angle grinder on it with one of these:

That pitted stuff has no structural integrity.

 

[borisbathtime]

Still looks far too rusty to me. Get that angle grinder on it with one of these:

View attachment 360950

That pitted stuff has no structural integrity.

That was just an initial quick cleanup to remove the flakey bits - of course as mentioned I’m going to try to remove more pitted stuff and get more bare metal showing but I can see where bare metal begins now and it looks treatable. The integrity of the vertical “I” section and the top horizontal section seem 100% just some loss of integrity on the bottom horizontal section (25% loss of thickness at its worst). At this point it looks treatable if done properly but I’ll need to keep an eye on it.
Correct me if I’m wrong but I believe the main strength in weight bearing of a rsj beam is the vertical “I” section and the horizontal sections are weight spreading ?

 

[lostinthelight]

Very good shout mate - two handed tools up a ladder was not a great idea - I think i'm going to go with a twist knot wire cup that fits my small hammer drill -I can operate that one handed while hanging on.
Once red oxide is on and dry any recommendations for a paint to topcoat over the oxide ?

I would forget a twisted cup brush in an electric drill, they dont run at a high enough speed,the balance is all wrong so could catch and jerk out of control

 

[Harry Bloomfield]

I would forget a twisted cup brush in an electric drill, they dont run at a high enough speed,the balance is all wrong so could catch and jerk out of control

They will, though, get right into the corners - where a disc cannot get to.

 

[catlad]

It looks like it has lost structural integrity.

Definitely not as strong as it once was. Hopefully it was over engineered. I'd consider putting an accro under it if I didn't need access for a vehicle.

 

[borisbathtime]

Definitely not as strong as it once was. Hopefully it was over engineered. I'd consider putting an accro under it if I didn't need access for a vehicle.

Yes I think you are right - it’s ok at the moment but in the long run a new structural supporting pillar (not offset) under the corner would be the plan - we never used the undercroft for a vehicle anyway.