Spray Foam Insulation in Sylvan Lake, AB.

65.9% of dwellings are single-detached and the stock is young, so the usual retrofit case — an old house with settled attic fill and no air barrier — applies to a minority of the town.

What does recur is geometry. Lakeside and bluff lots push buildings into shapes that are awkward to insulate with batts: walk-out lower levels that are below grade at the back and fully exposed at the front, rooms cantilevered out over open air, and vaulted ceilings with no attic above them to work in. And where a building is used seasonally rather than continuously, its envelope crosses the dew point far more often than an occupied house's does — which moves the priority from attic depth to a continuous air and vapour seal at rim joists, crawl spaces and roof-wall junctions.

The winter figures quoted here are Red Deer's. Sylvan Lake has no climate station, so the ledger assigns RED DEER REGIONAL A (climate ID 3025480), about 24 km east: 5,619 heating degree days at an 18 °C base, a January daily minimum averaging -17.6 °C and -43.8 °C at the recorded extreme. It is an airport reading taken on open ground, not a lakeside one — whatever moderating effect the lake has locally is not in that number.

Sylvan Lake draws over a million visitors a year, most of them in July and August (invest.sylvanlake.ca). Around the water the ledger names Sunbreaker Cove — its own summer-village municipality on the northwest shore, legally distinct from the Town of Sylvan Lake — and "The Slopes of Sylvan Lake," an estate-home development built into the lake's wooded bluffs (Alberta Major Projects).

Estate homes built into a wooded bluff are the assemblies described above in their most demanding form: stepped foundations, several roof planes meeting several wall planes, and living space above garage or open air rather than above conditioned rooms.