Joining RSJs

[igglepiggle3]

Hi.

We are hoping to have a extension built to our home and will be requiring RSJs to be installed, at the moment we have a flat roof extension at the rear and want to build up from that.



We have a existing steel beam in place which will need another one attached to it running towards the rear of the house and that one will then be connected to a new one running across the rear window forming an H shape if you looked down on them from above.



SE has said that the beam connecting the two will have to be joined by the web of the existing one because of the load so will have to be boxed round under the celing height.



This is the main thing that I did not want and wanted the joining beam to sit across the top of the other 2 in the celing void.



Can this not be done as wouldnt the load be the same on the beam anyway?



He should know about this as he has done our Planning And Building Regs which have both passed and I have mentioned many times that I did not want another boxed beam.


I feel very angry at the moment as we have spent £2500 on plans and fees since this started last August and to be told yesterday afternoon that the RSJ will be below the ceiling has is not acceptable .


Should I cancel his cheque and get another SE to sort it out as he is not doing what I want him to do?


Any help appreciated.

I stopped smoking in January and have never wanted one more than now!!!!

 

[^woody^]

It's hard to comment without knowing the layout, design or loads

Is he a proper structural engineer?

 

[tony1851]

Normal steelwork practice is to join beams meeting at right-angles by fixing into the web of the supporting beam. This means extra expense because it involves welding an endplate on the incoming beam, and some hole-drilling and bolting. For normal domestic loadings, though, it is usually possible to simply sit the incoming beam on top of the supporting beam without any bolting.

However, there is an important qualification, which might be applying in your case. If the existing beam is quite slender, when considering its span, it is possible that the additional load from the incoming beam would overstress it and cause it to buckle sideways. A way to prevent this is to rigidly restrain the beam, by bolting the incoming beam into the web. If this is the case, sitting the incoming beam on top of the existing beam would not be accepted as giving adequate lateral restraint - you would only be relying on friction.

As the previous poster said, it depends on the loadings, spans and the size of the existing beam(s). Having said that, SEs sometimes try and make life easy for themselves by not bothering to do proper figures. Ask why, and don't take this at face value.