Medvekoma I'm a bit late to this party but let me jump in here. Setting is every bit as important as knowing your characters back story. For instance, if your main character lives in a house with a "Gone With the Wind" style staircase that someone is going to get pushed down, you need to know that. Your readers will need to know that. Do they need to know that the banister has all these little wooden pieces that connect the top rail to the bottom and that the third one from the top is loose? Not unless you intend for the person falling to grab it to try to stop themselves or have a child you intend to let get their head stuck in the banister.

Just as the writer needs to know more back story about their characters than their reader does, they need to know more about their setting. Detailed drawings, magazine pictures, Sims houses designed to look like your setting. Whatever your favorite medium is you want to have a good handle on it. I mean no one wants to say the carpet was green in one chapter and blue in chapter six.

However, and this is a huge however, no one really cares what the carpet looks like unless it plays a huge role in the story. For instance, the King's home in J.R. Ward's Brotherhood Series, has a huge mural of a tree in the middle of the foyer. It is mentioned in every story and a lot of the big life events happen on that tree. The story would be lacking if she didn't mention the tree. She has to mention the security system every time its used or her readers would find it odd that she didn't. But, we don't need to know the place has both an indoor and outdoor pool in every book. We only need to know about the topiary when they crash a helicopter into it.

My settings for the current book consist of the following.
Tenyanie's house with emphasis on the mural in her dining room, and her book store.
Hayden's mansion including stables and surrounding fields(yes the cattle play a part in the story), office building, and warehouse but only the parts the reader would see. I need to know that there is an escape tunnel that leads to an old wooden shack by the Arkansas River, but my readers don't need to know it until the book where the shack plays a roll.

So make as detailed a setting profile for every location you will use. Just remember if your character never goes into the kitchen, telling us it has a state of the art onr, just ties up your word count in details that will bog down the story.