kneewall/dormer insulation retrofit: need expert advice
The sitch: 1922 1400sf bungalow with finished 1 1/2 floor/attic dormered living space. Too cold in winter, too hot in summer. Forced air heating has one vent to upper floor which is not very effective due to length of duct from basement. I blew cellulose into the ground floor walls last spring, but this has had little effect on the hot/cold conditions upstairs.
I want to retrofit the existing insulation in the triangular side attic spaces [see photo] off the finished dormered space.
Here's an illustration of the existing insulation scenario. The existing fiberglass batting is of unknown year, likely the 1970's, and has many gaps and holes. There is no vapor barrier present.
1. Everything I read (for instance) tells me that either the rafters OR the kneewall should be insulated, depending on whether I want this storage space to be part of the thermal envelope or not. As it stands, both have been insulated [a] and [b]. I'd like to retain the conditioned storage space if possible. Should I remove the kneewall insulation and focus on bolstering up the rafter insulation?
2. I assume I need to insulate the floor of the side attic [c]. I can't remove the rough flooring wood as it's a constituent part of the subfloor of the finished space [e]. Insulating on top of the floor seems pointless - I could potentially saw a hole and spray in foam between the cracks?
3. The venting situation baffles me. Ha. The side attics are not vented behind the fiberglass along the rafters, and there's a hole in the top where it abuts the kneewall, where [a] meets [b]. As far as I can tell there is no continuous vent on roof [d] leading up to the top attic space [g]. The roof of the side attic [b] simply meets the floor [c] with no apparent soffit vents. What to do about this?
4. My location is Cold Zone 1 (Maine), where R49 is recommended for attics. So I'll need a heck of a lot more than the existing R13 - best way to achieve this might be a combo of fiberglass batt with rigid foam boards? Can I perhaps use the boards to create the vented space along the rafters, with fiberglass on top, then a vapor barrier? I don't mind furring out the rafters, etc, if it will let me get the proper amount of R-value in there.
I'll stop here and if anyone is so kind as to give me a few tips as I begin, I'd be very grateful. Thank you!