Moreso than many other industries, construction work is variable. For one, it tends to be heavily project-based: rather than going into the same office every day from 9-5, employees work on a particular building or structure and then move on to a different site. Also, there are often permits to wait for or paperwork that needs to be attended to before building can start. Even something as ephemeral as weather can affect the ability of a crew to move forward with work.
Because of this, the insurance situation can become fairly complicated. Even if you have California contractor insurance that protects your site and your business, you might still need to provide your workers with health coverage. Whether or not this is the case depends on your particular adherence to certain stipulations in the Affordable Care Act.
In essence, you are required to cover any employees who work for you on a regular and ongoing basis. The act defines this as an average of 30 hours per week. For seasonal employees, this mean is calculated based on a time period of the employer's choosing, which is usually three, six or 12 months long.
If you're thinking about gerrymandering your workers' hours to skirt these guidelines, you might want to think again. The government is cracking down on companies that try to game the system in this way, and could levy penalties. If an employee goes to the public exchange to get coverage, you might be faced with an information request about their exact hours and schedule. If it doesn't seem legitimate, or if you are unable to produce this data, you could be on the hook for that staff member's policy. Thus, it's critical to keep detailed notes on all of your staffing decisions.