I have a 40 year old house in Southern Ontario with a belly in it. It runs from ridge to the facia and from gable end to gable end. The trusses appear to be hand cut and made on site. What would be a way of taking the belly out of it. They used 1x6 boards to cover it. I tought of laying out a new roof on top and support it where necessary, but how would I vent it?