i am having a extension built with bi folding doors spanning 8mtrs i am using columns to support part of the load of the rsj which is supporting the roof do the columns need there own pads to sit on

In response to your question ! When i use this method of inner leaf columns to support the inner leaf RSJ i was made to dig a 500 x 500 x500 hole with300 mm of concrete in the bottom and a 9 newton concrete pad layed under the girder. As you can well apreciate all jobs are different. On another project of mine i was made to weld a plate on the bottom of the rsj and bolt directly to the floor. Hope this helps Regards ken

These are questions for your architect & structural engineer.

There would be three different methods to catch the load that spring to mind. Each would need structural calcs and drawings for building regs, but at least you can explore the cost implications of each before deciding what works for you. A standard pad dug A reinforced or oversized floorslab where the weight would sit Or a groundbeam to span the 8 metres, on which the load can be transferred. I hope this helps. Kind regards, Craig

Normally this detail is shown on the building reg drawing if you have no drawing then . ask the building inspector for advise after all he has to inspect the columns and pass them Malcolm