Property values are allocated by the value of the homes in it, so the higher the value the higher the property tax. property taxes are increased 2% every year after the purchase date. Below is a link to give you a little more in depth information about it.
California's tax on real estate, is 1 percent of the property's base value. The property tax base is increased 2 percent each year after purchase.
Improvements will have change the value and the tax,when the property is sold or transferred from one owner to another, the tax base will be reassessed at 1 percent of the selling price. So if the improvements increased value..taxes will go up.