Single Storey Extension 7m RSJ

[SJSbuilding]

All,

thinking of building a single storey extension on the back of my house that would include removing the rear wall and fitting a 7m RSJ (to open it up into a more square room) is a 7m RSJ realistic ? cant find much info online of builds what that sort of size beam, or would it be way to hard to prop up ? any info would be appreciated before i start paying structural engineers and architects, Ta.[/QUOTE

 

[SJSbuilding]

Hi, you probably built the knock through but here's some info for other readers.
The design of the steel will depend on the loadings/span.
Most SE just punch in figures into a design program and out pops the steel size. If the wall is a solid brick or block wall then I would use two PFC's bolted back to back, we have also used UB's with spacers and bolts (stud) Two steels will be more expensive than one but it's a lot easier to insert one steel make foot and then install the other.
If you have a cavity wall then it's completely different and it's a case of either "strong boys" or props and pins, depending on the width/height and loadings.
I have designed steels with welded plates to eithe the top or bottom flange to support a cavity leaf, and others to span cavities.
End bearings will depend on the loadings, crushing strength of the brick/block under the steel. Sometimes they can sit directly on the brick/block, sometimes it requires a pad stone or steel plates. If the wall below can't take the loading due to its strength or thickness to width ratio (buckling) then steel columns may be the answer. Either as a goal post or picture frame design. The choice mainly due to the design of the foundation and the fact you can't undermine your neighbours house to install a large concrete foundation for the goal post system.