Sill, sill, sills
One word for many things.
Some words get applied to many things, which can create confusion.
Take the word sill, for instance; almost all the meanings relate to something in your home.
There is the sill of a door or window. A stool is the little wooden shelf at the bottom of the window that you see in your house; this is not it. The sill is the framing that is under the window that the window sits on. There is also a piece of trim on the window called the sill, but it’s on the outside of the window and slopped for water.
But we are not interested in that sill.
We want to talk about the sills in your crawlspace. We believe the term properly applied is for only one item in the crawlspace. But there are at least three things this term gets applied to, so let’s talk about them all.
The first, the original and correct one, is the sill that sits under the band or under the girders. This flat piece of treated wood separates the foundation walls or piers from the framing. It serves as a capillary break, meaning it prevents water from wicking off the masonry and to the framing.
It’s purpose is to be the part that gets wet, so it’s treated to prevent rot. It lays flat, so the framing has something nice to sit on.
The other two things that get called sill in the crawl space are girders with joists on top of them. This is sometimes called a drop sill or a sill beam.
The other is what is known as a ledger board. The ledger board is a smaller board nailed to the band or girder that the joists sit on. This is like the original wooden version of a joist hanger. This is sometimes referred to as a rat sill, though let’s be honest, the ledger sounds much nicer.