I have an 850 sq/ft cottage/home (currently used as a 10 day/month cottage year round) heated with oil.
Located in Kenora, Ontario, Canada P9N0E7.
Standard early-90's 2x6 home construction, no exterior foam, tri-pane windows and a double pane sliding door to deck.
The design is simple, a 5/12 (gable) roof covers the home, the ridge line runs n/s. its roughly 30 x 27.
The east side has two rooms; the MBR (at the south end) which has a huge east facing window (and a narrow south facing window) and the living room which has the sliding dual pane door onto the deck (and two n facing windows). Both of these rooms have a sloped ceiling. I can see the pitch is the same on the inside as the exterior so its probably (don't know and don't know how to find out) a vented 2 x 10 or maybe 2 x 12 sandwich with this lay up I suspect from what I can see...
clear interlocking 1 x 6 cedar (or pine)
5/8 drywall
vapor barrier (6 mil poly was standard and is visible on exterior wall openings)
fiberglass batts to fill the roof bays; maybe leaving a gap at the top for ventilation (but maybe not)
7/16 or maybe 1/2 plywood on roof deck covered by a single layer of very tired asphalt shingles.
the west side of the house has (from s to n) kitchen, bath, 2nd bedroom, all under a standard 8' flat roof.
I have been in the attic (south side of house has a gable door which allows access to flat roof) I can see two layers of R20 then R12 fiberglass insulation here.
My plan is to blow cellulose on top of the fiberglass to a total of about R60.
Since the shingles are coming off anyway this spring I would appreciate some ideas on how to increase the insulation on the east side of the house (the sloped roof).
I considered adding 2" of rigid foam to the exterior roof deck but wonder if that is smart since I don't know the roof stack up on the east side.
Also, if the roof deck gets two inches taller on the east side how does one mate with the 2" gap at the ridge line; I assume there is no point in adding foam to the exterior of the west side since that is a flat insulated ceiling.
edit///
It just occurred to me that adding the foam to the interior might work! Any thoughts? The reason this was initially discarded as a possibility is the ceiling is finished with interlocking cedar boards and to lose that would be a tragedy. Besides the roof deck is bare when shingeling so that seems like a better place to put it....if it works there.