I want to remodel a custom house how much would it cost?

The best thing for you to do is contact a contractor because there is a lot that needs to be considered when you are looking for pricing. Sq Footage, materials, permits, plans... Try calling Green Planet Building of Los Angeles they will help you. Their website is www.greenplanetbuilding.com you can see the kind of quality work they do. They are eco-friendly contractors that do remodeling and custom building with out it costing anymore than regular construction.