Skylight heat loss insulation is rarely just about the glass overhead. A homeowner feels a cold drop of air near the dining-table skylight each January. The ceiling around it seems colder than the rest of the room. Maybe there is a faint line of staining at one corner. Maybe the skylight looks fine from inside, so the instinct is to blame the glazing or buy a heavier shade.
In many Massachusetts homes, the roof skylight is connected to the finished ceiling by a framed shaft, often called a light well. When that shaft passes through a cold, vented attic, it becomes a vertical section of the home’s enclosure. If the shaft walls are not continuously insulated and aligned with an air barrier, the ceiling opening can become a forgotten path for heat loss, air movement, or moisture-related trouble.
