My house is 12 years old. The living room is cathedral ceiling ( 14 ft ) and the foyer is open to the top floor (17ft) The other rooms are only 8ft however. Floor joists are 2x12. My dining room is 13x14 and I would like to create a coffered ceiling. This would involve cutting the joists in half about 1 ft in from each wall and then installing reinforcements on either side, perhaps installing additional joists as well. The span supported by the thinner joists would be 11 ft. The room above is a bedroom with wood floors. This would create a nice architectural effect and give the feeling of a bit more head room. I have seen 5 3/4 inch engineered joists in the UK, but don't know if they are available here in Canada. Is this idea feasible?