I have a 1960's ranch with 2x8 floor joists. Basement floor to bottom of joists is only 7 feet. A bathroom in the basement has heating and air ducts running across perpendicular to floor joists leaving only just over 6 feet of head room. I would like to modify this situation to give me more head room. My thought is to header off the section where the bathroom is and move the ducts up to get more head room. The areas on either side are unfinished so the span would be less than 10 feet. any ideas? Also there are a couple of taps from this trunk line in the bathroom so the header would have to be open truss.