window sill replacement

Window Sill Replacement

The window sill is the surface at the bottom of a window. It’s always flat and made from a rigid material like wood, metal, or glass. That allows it to support the window and ensure that you can place heavy objects without the sill breaking. 

It’s not technically part of a window, but it still requires replacement at some point. Over time, the window sill can get damaged from wear and tear, or even worse, could get broken.

Having that in mind, we wanted to give you a guide that will tell you everything you need to know about window sills and their replacement. 

Is a Sill Plate Structural?

The window sill is also called the sill plate, but most carpenters in North America omit the word ‘plate’ from the name, which may be confusing for some.

The sill plate is indeed structural, as it’s one of the most important elements in the whole window construction. 

You will hardly ever see a house or an apartment that doesn’t have sill plates on the windows. They are essential for supporting the window, but they are also used on the outside to keep water out. Without the window sill on the outside, moisture could damage the construction of the window over time. On the inside, most of their importance lies in the fact that they support the weight of the window. What’s more, the sill holds it in place. 

How Do You Replace a Wooden Window Sill?

Many older houses have wooden window sills. However, these get damaged over time from the elements. Rotting is inevitable in wooden sills, no matter how much you take care of them. Thus, replacing them becomes unavoidable as well.

You can either call the professionals, or you can replace the window sill on your own by following this relatively simple procedure:

  • Use a knife and a hammer to break and remove the caulk. Then use a crowbar or a chisel to pry the sill off carefully. Use the wooden sill’s measurements to get a new one.
  • Clean all the debris and rot.
  • When you get a new sill, you need to use nails or screws to fix in place.
  • Use a caulk gun and apply caulk along the edges of your new sill.

How Much Does It Cost to Replace a Window Sill?

The cost of replacing a window sill can vary from place to place. In general, the DIY method is cheaper, as long as you have most of the tools we mentioned in the previous section.

If you don’t, or if you want to hire a professional, the cost will usually be around $130. That includes the cost of replacement and the cost of the new window sill.


A window sill is one of the essential parts of a window, and its replacement is important if the old sill is no longer functional. If a window sill on one of your windows is damaged or rotten, you should change it as soon as possible.

We at 1-800-HANSONS can help you by providing you with the type of sill you want and its installment. You can get a free estimate whenever it suits you!