A window without a sill wouldn’t be a window, and it’s been this way for many years. Let’s take a look at everything you could want to know about window sills. <\/p>\n\n\n\n
What Is The Purpose Of A Window Sill?<\/h2>\n\n\n\n
The window sill is an underrated architectural feature. But what purpose does it serve?<\/p>\n\n\n\n
- It’s part of the window structure \u2014<\/em> The sill shapes the base of the window, providing both structure and support. Without the window sill, the frame would be far more susceptible to shifting in the wall, causing damage to the window and the exterior walls. <\/li>
- A barrier between the outside and inside \u2014 <\/em>The downward slope of the window sill allows snow and water to fall off as quickly as it lands. Water may seep into the walls without the window sill, causing lasting structural damage.<\/li><\/ul>\n\n\n\n
Even the simplest of features like a sill can save you from having to fix compromised structural integrity.<\/p>\n\n\n\n
Types Of Window Sills <\/h2>\n\n\n\n
When trying to classify window sills, you’ll find that there are generally two categories of window sills: interior and exterior.<\/p>\n\n\n\n
As the name states, interior window sills<\/a> are found inside the home, and exterior ones are located outside the home. <\/p>\n\n\n\n
Interior window sills will have a trim surrounding the window, and most people will use this sill to store or display items<\/strong>:<\/p>\n\n\n\n
![\"Coffee](\"https:\/\/cohesivehomes.com\/wp-content\/uploads\/2021\/09\/Coffee-mug-on-top-of-a-window-sill-1024x683.jpg\")
Coffee mug on top of a window sill<\/figcaption><\/figure><\/div>\n\n\n\n There is not need for them to be angled because they don’t have to face the harsh weather conditions exterior sills do.<\/p>\n\n\n\n
Exterior window sills are geared towards protection against water damage. These sills need to be angled to direct water away from your home<\/strong>:<\/p>\n\n\n\n
![\"A](\"https:\/\/cohesivehomes.com\/wp-content\/uploads\/2021\/06\/A-basic-UPVC-plastic-window-sill.jpg\")
A basic UPVC plastic window sill<\/figcaption><\/figure><\/div>\n\n\n\n Why Should Window Sills Be Angled?<\/h2>\n\n\n\n
Alright, so the purpose of a window sill is to direct water away from interior spaces, but why should it be angled?<\/p>\n\n\n\n
- Structural support \u2014 <\/em>As mentioned above, the window sill acts as a support structure for the rest of the window. It also holds the window sash in place when the window is closed.\u00a0<\/li>
- Energy-saving feature \u2014<\/em> Window sills protect interior rooms from drafts by creating an airtight seal. Tightly sealed windows mean less electricity for heating and cooling<\/a>, saving you money on your electricity bill.<\/li>
- Protection against the elements \u2014 <\/em>Besides keeping water and wind at bay, window sills also prevent mold from forming<\/a> on your windows and in your walls.\u00a0<\/li>
- Design feature \u2014 <\/em>A window sill can act as a permanent shelf. The downward sloping sill will help any water drain away from the house if you plan to install flower boxes.\u00a0<\/li><\/ul>\n\n\n\n
Angled window sills simply make sense.\u00a0If you were to have a flat window sill, any water or snow that finds its way to your window wouldn’t have a means of escaping, other than through evaporation.<\/strong>\u00a0<\/p>\n\n\n\n
If water is left on your sill and allowed to heat up through sun rays, it could cause discoloration or bubbling of paint on sills, as well as increased deterioration of wooden window sills. <\/p>\n\n\n\n
In the most extreme cases, pooling water on your window sill can penetrate your interior walls, causing damp and flaking interior paint. Other than flaking paint, you can also run the risk of mold growth in your walls and around your windows. <\/p>\n\n\n\n
Any mold growth in your interior walls could pose a threat to your home’s structure and your health, as some molds can be toxic<\/a>.\u00a0<\/p>\n\n\n\n
What Is The Correct Angle For A Window Sill?<\/h2>\n\n\n\n
To minimize and avoid water infiltration, you want to ensure that your window sill is at an optimal angle. <\/p>\n\n\n\n
If the angle isn’t accurate, you won’t have a tight seal between the window sill and the window frame. A wrong window sill angle will compromise the water-wicking ability of the sill.<\/p>\n\n\n\n
Generally, you’ll find that sills range between 7 to 15 degrees in slope angle<\/strong>:<\/p>\n\n\n\n
![\"A](\"https:\/\/cohesivehomes.com\/wp-content\/uploads\/2022\/04\/A-diagram-showing-a-7-15-and-45-degree-angle-for-window-sill-purposes-1024x712.png\")
A diagram showing a 7 15 and 45 degree angle for window sill purposes<\/figcaption><\/figure><\/div>\n\n\n\n If you want to calculate the slope of your window, this post<\/a> gives you three ways to do so, with diagrams, charts, and various tools to ensure you get the most accurate sill angle measurement.\u00a0<\/p>\n\n\n\n
Can Window Sills Be Flat?<\/h2>\n\n\n\n
Technically speaking, your window sill can be flat. Would it be a good idea to make your window sill flat? Probably not. <\/p>\n\n\n\n
Besides the reasons mentioned earlier as to why you want an angled window sill, window sills are necessary for any window structure. <\/p>\n\n\n\n
The sill provides a natural stop to the lower rail of the window and holds the window sash in place when the window is closed. <\/p>\n\n\n\n
- Energy-saving feature \u2014<\/em> Window sills protect interior rooms from drafts by creating an airtight seal. Tightly sealed windows mean less electricity for heating and cooling<\/a>, saving you money on your electricity bill.<\/li>
- A barrier between the outside and inside \u2014 <\/em>The downward slope of the window sill allows snow and water to fall off as quickly as it lands. Water may seep into the walls without the window sill, causing lasting structural damage.<\/li><\/ul>\n\n\n\n
![\"A](\"https:\/\/cohesivehomes.com\/wp-content\/uploads\/2020\/11\/A-block-and-brick-built-new-construction-home-with-some-windows-not-installed-1024x768.jpg\")
![\"Various](\"https:\/\/cohesivehomes.com\/wp-content\/uploads\/2022\/04\/Various-microfiber-clothes-1024x680.jpg\")