We are getting ready to replace the roof on our 20 year old home (in Michigan). In the process we would like to increase our attic ventilation and are considering a ridge vent to replace our existing roof vents. We currently have soffit vents, however not enough to balance a ridge vent on the full length of the house. We would like to avoid changing the soffit vents if at all possible. I am wondering if there is a down side to installing a ridge vent on 18 feet (spread across the peak in 2 foot sections) of the approx. 30 foot roof, which would balance the amount of soffit ventilation we have. (We would have the ridge vent installed the full length of the house for asthetic purposes, but only cut 2 foot sections of the roof decking to equal 18 feet instead of 30.) Any thoughts would be appreciated.