Bedroom, Bed, Medium Hardwood Floor, and Wall Lighting Always put contingencies aside. During any renovation, it is critical to set aside money for the "what if" or emergency scenarios. For example, there might be plumbing that you didn’t anticipate needing to replace. Conventional wisdom suggests adding 15 to 20 percent to your contractor’s renovation cost to safely consider these contingencies.  Photo 5 of 12 in Ray Kappe-Designed Multilevel House in Los Angeles

Ray Kappe-Designed Multilevel House in Los Angeles

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In addition to wood and concrete, the other main material in the house is quarter-inch single-pane glass: No room is without a natural light source, whether from skylights, mitered corner windows, or clerestories, as in the old bedroom of the Kappes' son Finn. The paintings are by their other son, Ron.