Yes, 12-inch shelves are often considered the standard closet shelf depth for storing folded clothing, shoes, and small containers. However, if you plan to store bulky items such as blankets, baskets, or cleaning supplies, you may want to go deeper. For specialized layouts, an adjustable system can give you more flexibility.

There are a few reasons custom closets are expensive: materials used, the luxury factor, and time to build. The people who can afford custom closets are those who can afford increased rates, and construction workers and contractors know this and charge accordingly. The time to build custom closets is substantial, especially if expensive material is being used or intricate details (like carved wood) are added to the project. 

How many days it takes to remodel a closet will also depend on the scale of the project. Small changes like installing a prefab kit will eat up an afternoon and no more, while a total renovation could require several days to a week. If you’re planning for the latter, plan to secure other sleeping arrangements while construction is ongoing.

You may need a building permit to add a closet, depending on the size and kind of work required to install it. The most likely scenario requiring a permit involves changing the structure of the house and performing electrical work for closet lighting. A permit can cost between $100 and $450. If you’re installing a smaller reach-in closet, a permit may not be required, but always check with your local municipality and consult a closet designer or builder.