In Hermosa Beach, the city's Building and Safety Division issues building permits, including for alterations to an existing house, and it plan-checks a project before the permit goes out. Whether your insulation job needs one depends on the work, so I look up what the city asks for at your address and tell you at the estimate. When a permit is needed, we handle the application and build the plan check into your start date. You can check one thing about any contractor yourself. The city's Revenue Services Division issues business licenses, and they run one year, so ask to see a current one.
The price here mostly comes down to what's already in the attic: how many inches are up there, whether any of it has to come out, how much sealing the gaps need, and whether we're blowing in loose fill or spraying foam. The schedule turns on the same things, plus a permit or an asbestos step on older houses when one applies. We work the same way next door in Manhattan Beach and over in Palos Verdes Estates.