Flaking rusting RSJ

[DoughnutDave]

Hi, I just wondered if anyone could help me. Just moved to a new house and on looking in the side void area, I noticed the RSJs in there have almost an orange peel dimple effect and big pieces of the red paint have fallen off around the RSJs. Unfortunately I can't get in a lot of the area to rub down and repaint. Some of the pieces of paint are a few mm thick with paint on one side and rusty metal on the other. Is this an issue?

I can't work out how to upload my picture, sorry.

 

[tony1851]

Is this an issue?

It might be in about 200 years.

 

[ban-all-sheds]

I can't work out how to upload my picture, sorry.

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Alternatively use an image hosting site, e.g. http://postimage.org/ (other sites are available) to upload your images.

Some hosting sites don't allow direct links to the images, and make you use thumbnails, but if so the good ones will provide the code all packaged and ready to paste in.

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[DoughnutDave]

View media item 74885

 

[DoughnutDave]

A piece of the metal/paint that has fallen off.

 

[tony1851]

In a heated house, the initial loss of steel to rust over the first year or so will be around 0.01 to 0.02 mm (say 0.015). This forms a firm coating on the steel which, if left undisturbed, will slow the loss of steel down to about 0.01mm/year.

Much of the strength of a steel beam lies in the web (the vertical part), and in a typical domestic setting, the web of a steel beam will be around 5mm thick. So if we assume that the strength begins to become compromised when the web is down to - say - 3mm thick, then that gives it around 200 years.

Post back then for further advice if it's any thinner.

 

[Guitar_man]

If you can get access (which is sounds like you can't), then you can scrub it with a wire brush. Wear goggles is imperative. Then you can repaint with red oxide. Take a picture you can show for when you sell on the house.
Typical life is at least 60 years if left outside in the cold and the rain..

 

[tony1851]

Typical life is at least 60 years if left outside in the cold and the rain..

Are you referring here to the red oxide coating lasting 60 years?

 

[Guitar_man]

Typical life is at least 60 years if left outside in the cold and the rain..

Are you referring here to the red oxide coating lasting 60 years?

No I was referring to the life of the beam in a cold and wet environment.

 

[tony1851]

That could well be about right, so presumably if it's indoors - dry and relatively warm - and not subject to abrasion by wind etc, it should easily last a lot longer than 60 years.