Just built a 35'X40' garage with 11' ceilings. I used pre-engineered trusses for the hip roof. I have a 4" soffit, non-vented in anticipation of foaming the roof. The roof pitch is 14/12 on two sides and 8/12 on the other two. This made a really large roof area. I purchased a LG 18,000 24 SEER...