Why does an inspector note an attic hatch with no insulation or weatherstripping?

The ceiling plane of a vented attic is a thermal and air barrier, and an attic hatch is a hole cut straight through it. Uninsulated and unweatherstripped, that hole loses heat by conduction through the thin panel and, more significantly, by air leakage around its perimeter — warm moist indoor air escaping into a cold attic. The air leakage is the part with consequences beyond energy: that moisture condenses on cold sheathing and can produce frost, staining and mould directly above the hatch, which is why the area around an attic access is a common place to find those conditions. The remedy is simple and cheap — rigid insulation on the panel and weatherstripping around the frame, with a latch to compress it — which makes this a high-value item in the report despite sounding minor.

The hatch is an opening through the insulated and air-sealed ceiling plane, so without insulation and weatherstripping it loses heat and leaks warm moist air into the attic, where the moisture condenses on cold surfaces.

In a vented attic the ceiling plane carries the insulation and air barrier. Attic hatches, pull-down stairs and recessed lights are common breaches, and air leakage through them carries moisture into the attic where it condenses.

A Hole in the Blanket. The insulation stops at the hatch, and the warm wet air goes straight up through the gap around it.

Look for frost or staining on the sheathing directly above the hatch in cold weather. It confirms the air leakage rather than just the missing insulation.

• •Reporting missing insulation without the air leakage consequence
• •Overlooking pull-down stairs, which are a larger version of the same breach
• •Missing condensation evidence directly above the opening