ON THE EVENING of January 7th Steve Gibson and his wife Charlotte saw a glow in the sky. “We opened the door and the street lights were out, but there were embers in the air,” he recalls. The Eaton Fire was closing in on their little house in west Altadena. Their home burned, along with more than 16,000 other buildings across Los Angeles County that month. The six months since have been a confusing whirl of hotel stays, paperwork and questions about how to rebuild. Mr Gibson craved speed, so he turned to Cover, a startup that builds granny flats (Americans call them accessory dwelling units, or ADUs), at its factory south of Los Angeles.