#Windowsill September 18

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September 2026 several of us are going to take on the 30-Day Architectural Coach4aday Challenge each day, we will define an architectural term and provide examples of where it is located. This challenge will let observation, travel, history, and photography all intersect. For Day 18 it is a WINDOWSILL.

Of all the architectural terms I’ve encountered this month, today’s word—windowsill—is probably one of the most familiar to me.

I’ve used the word countless times and would have said I had a pretty good understanding of what a windowsill is. But that’s one of the things I’m enjoying about this month’s challenge: even when I think I know a term, there is usually something more to discover.

My research on the windowsill taught me a few things I didn’t know about its purpose, construction and history. It was another good reminder of why I enjoy these challenges. They push us to look more closely at familiar things, ask questions and discover something new. Even when we think we already know a subject, there is always more to learn.

30-Day Architectural Challenge Guidelines

If you have ever watched Seinfeld, you know that George Constanza always wanted to pretend to be an architect

Well, this month’s challenge let’s all of us that are not architects learn a little more about their language. To do that we have a simple challenge.

Every day we’ll learn one architectural term. Your challenge is to find an example—preferably one you’ve actually seen—and share a photograph, location and brief explanation.

Day 18-Windowsill

Here is a video I located on Study.com that covers different types along with its purpose.

Finally, here is a video talking about 4 reasons that architects should use a windowsill.