Termite Control in San Francisco, CA

Local Context

Old-Growth Redwood, Shared Party Walls, and a Colony That Never Has to Fly

The city's pre-1915 stock gives drywood termites an unusual amount of old wood to work with. Italianate, Stick and Queen Anne Victorians, and the Edwardian flats rebuilt after 1906, were framed in old-growth redwood and Douglas fir. That is tight-grained wood, and it stays sound for a century while feeding Incisitermes minor the whole time. The colony lives inside the member. On a Noe Valley or Castro building the first sign is usually a small cone of six-sided frass pellets on a windowsill, under a pinhole in the trim.

Row construction changes the math. Where buildings share party walls, as they do across the Western Addition, the Mission and the blocks below Alamo Square, a colony can extend sideways through connected framing without ever swarming to start somewhere new. That is why a neighbor's finding matters to your building, and why an inspection here has to read the shared wall and the light well, not just your own rooms.

The fog sorts the species. West of Twin Peaks, the Sunset and the Richmond sit under marine air most of the summer, and the soil stays damp enough for Reticulitermes to forage year-round and build mud tubes up foundation walls. East and south of the ridge, through the Mission, Bernal Heights and Potrero Hill, the ground runs warmer and drier, which favors drywood flights. September is the city's warmest month, with average highs near 70°F, and that is when the swarm calls come in.