Gap between exterior insulation and soffit

A homeowner working on their own siding upgrade posted a question that's worth knowing about if you're planning a similar project. After adding 2 inches of exterior foam insulation to a gable wall, they found small gaps, about a quarter inch in spots, between the top of the foam and the soffit (the underside of the roof overhang). Before installing the house wrap and rain screen (a small air gap behind the siding that lets moisture drain and dry), they wanted to know the best way to close that gap so insects don't move in.

This is a common detail question in exterior insulation retrofits, where rigid foam is added to the outside of a house's walls to boost its insulation value. Gaps at transition points, like where foam meets a soffit, roofline, or trim, are typical trouble spots. Left open, they can let in insects, pests, or moisture, and can also undercut the energy performance of the upgrade by letting air leak through.

For anyone doing or planning a similar exterior insulation job, it's a reminder that the small connection points, not just the big flat wall areas, are what make or break an air-sealing job. If you're getting exterior foam installed on your own home, it's worth asking how installers plan to handle transitions at soffits, corners, and window trim before the siding goes on, since those gaps are much easier to fix at that stage than after everything is closed up.