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 5 in Tiny Sleeping Nooks by Allie Weiss from Ray Kappe-Designed Multilevel House in Los Angeles

Tiny Sleeping Nooks

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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.