- Slab on grade construction.
- House built 1938, slab poured in 1950's we think. San Francisco area.
- New framing, new hardwood floor, new baseboards. Completion 6 months ago.
- Altriset and Termidor (both) pumped under slab to control prior termite issue.
- Adjacent room is unfinished basement space. There's concrete but no particular source of debris.
Every week or so we vacuum up what seems to be sand from the top of the hardwood floor. It seems to blow out from under the baseboard. What could cause this?