In many cases, it's more economical to rejuvenate wood windows than to replace them. This is especially true if you consider the historic character and value of original windows. Often the deciding factor is the condition of the sill. Where the sill is shot, people often opt for complete replacement, frame and all. However, if the sill was repaired or replaced, the window could be saved. Here are a few methods I've used to deal with bad sills. Sills First let's review a few basics of function and construction. The sill is a structural part of the frame that holds the sash snugly, yet lets the sash open and close freely. A weather seal is formed between the bottom