Even with the over-sized double barrel stove pumping heat at full capacity, the house remains largely uninhabitable. Temperatures now regularly dipping into the teens and below, the hot air is almost immediately sucked out of the porous roof and cracked windows. Bare rafters and uninsulated plaster walls do little to help. The 1890 house was built with virtually no insulation. Luckily for us, the rear extension was (date unknown - but late enough to have used gypsum board instead of plaster+lath). Since this space is not in a state which is currently useful to us, and because water damage warrants substantial rebuilding anyway, we're able to reappropriate this material where it's far more useful.
The severity of structural problems becomes more apparent each time we work in this room. As we pull off pieces of drywall - which we expected to come down in handfuls because of painted over screws, they instead come off in full sheets, often taking the studs they were attached to with them. The pulpous 2x4's which once rigidly held the walls in place explode into dozens of soft shards with the lightest of tosses.
Fortunately this kind of damage is present only in a few isolated areas, and so we are able to scavenge enough batt insulation for almost the entire roof above the stove.
Scraps of rigid insulation in varying sizes, colors, and origins are used as a first defense. These aren't as prone to water damage as batt insulation is, and can withstand any leaks that our quick roof patching failed to catch. A few $3 cans of expandable foam seal the cracks and go a long way in keeping heat from escaping. With the largely airtight seal established, the fiberglass insulation is packed in with lathing strips until a "finish" surface can be applied.
Having this pitched space insulated - in combination with the large hole above the stove - creates a pocket of space in which the heat can sit. After eagerly moving our sleeping space upstairs, we hold back our first reactions in respect for our hard work: it's too hot.