Hanging Wooden Joists Below a RSJ

[LondonLad21]

Morning all

Doing a single storey extension at home presently.

Was hoping to put the roof on now, but seems have hit an issue.

Typical 30's semi, dining room, with 3m opening on back of existing house. Opened up the ceiling over that opening, and it seems the rear of the house is supported by two good size steels (one for outer wall, one for inner)

The real pain, is the steels are set 175mm HIGHER than the ceiling....never expected that.

It means that if I fix the flat roof to that steel, the roof will be too high for planning.

I need to sling joists below it, spoken to a chippy and he's worried that it will be an issue, see his point, as any joist hanger will cause a twisting force on the joist.

What do people do in this situation?

Thanks, enjoy the holiday.

 

[cdbe]

I wonder if there's a reason he's a carpenter and not an engineer......

 

[tony1851]

It's very unlikely that a flat roof to a domestic extension will put an undue twisting force on a steel beam which is supporting an outer skin.