I am in the process of tackling the air sealing/insulation/venting of my attic in order to prevent heat loss and the formation of gigantic killer icicles. I am in the middle of the process and could use some advice/guidance.
The Current Situation:
I live in a 2-story house built in 1902. The house is stucco with balloon framing and is in Ontario Canada. The attic is roughly 1000 sq ft, has maybe 3 inches of old loose insulation (maybe r-10?) between the ceiling joists. Venting is exhausted by 2 whirlybird type vents and I am in the precess of adding intake vents in the soffits. There are cathedral ceiling on the second floor. These ceilings are plaster on 2x4 rafters. The roof was recently done and I had the space between the ceiling and the sheeting insulated with 2 inches of rigid foam, which left a 2 inch air gap for air flow from the soffit vents into the attic (not ideal but better than nothing, and I did not want to reframe the roof with larger rafters for more insulation). I have capped the balloon framing on the gable ends with rigid foam and spray foam (can-type). Walls are not insulated. Crawl space dirt floor has been poly'd and the foundation walls spray foamed.
I was thinking of adding soffit gaurds, adding a layer of poly over the entire floor of the attic to help air-seal, and then blowing in cellulose insulation to about R-50.
Thoughts on this plan? I'd love to prevent the loss of heat into the attic to save on $ and to prevent giant icicle formation. But I'd also like not to cause other issues that I may be overlooking.