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Postby Yorkshireshrek » Fri Nov 14, 2008 6:43 pm

Hi, I have two horizontal RSJs encased in a cement block above my external garage door which support one end of a steel sheeted roof. I have been told by 2 builders that the RSJs have corroded causing some of the concrete to crack, with a large lump falling out due to the RSJs expanding and contracting. One builder insisted I need to replace both RSJs but the other suggests it is generally sound and I only need to repair the section of cracked concrete with some more cement. Exposing the RSJs to clean off the rust is not an easy option. Should I replace it or repair? - will repair work just result in more cracking and if it does crack, is it just a cosmetic problem? I am on a limited budget and if I can get another 10 or 15 years with a repair then I am keen to save money
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Postby the specialist » Sat Jan 10, 2009 3:05 pm


I don't know if your sorted yet.

The rsj's if corroding actually delaminate which makes them bigger. They do NOT then shrink again. If they continue to corrode they continue to delaminate. They probably still have structural integrity sufficient to do the job they are intended for.

You do need to take some action and the cheapest is to expose the ends and clean with wire brush and then treat with red oxide paint. After this they can be encased back in concrete. This should extend the life of the rsj's. This is a cheaper option than replacing them. I'm not saying they will last forever but should by you time.

Good luck.

the specialist
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Postby TheDoctor5 » Wed Jan 21, 2009 2:09 pm

Last year 64% of the questions asked in our forum were answered within our DIY project pages at The project pages are now separated alphabetically and your answers are accompanied by diagrams and the ability to see, and buy, the tools and/or required to complete your project. Use our search box to look for your answer and save a great deal of time and money!
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