I have an existing loft where the joists are Imperial and measure 7" x
2". The unsupported span being 4 Metres. I would like to raise the loft roof and use this area as a new room. The 7" x 2" joists seem to be right on the limit for a 4 Metre span. How does it sound if I stand 4" x 2" timber on top of the 7 x 2's to make a composite joist of 11" x 2". I would use 'gangnail' plates at say 400mm. spaceing to join the two joists together. I can afford to loose 4" in room height with the 4" x 2" stiffening joist. Does this sound a kosha method of doing it?Regards Chris.