The only sill I ever heard of is a window sill. What about you? Have you ever heard of any other kinds of sills? Based on conversations about leveling your home with a foundation repair contractor, you’re starting to figure out that apparently there’s a bunch of different kinds of sills on crawlspace homes like pier and beam and block and base foundation types. Who knew?
At Anchor Foundation Repair, we’ve known all along in our 35+ years in business that there are different types of sills, but that’s because this is kinda *our thing*. We’ve worked on 1000+ crawlspace homes in the Brazos Valley area since 1985. We can fill you in on the terminology that goes along with restoring the proper support and stability to your crawlspace foundation.
This article will define the term sill within the home foundation and repair context. Then we will review 4 types of sills found on crawlspace homes and their purpose and importance within the home structure. That way when you hear someone talking in foundation “industry-speak”, you can follow along.
Definition of the Word Sill in Foundation Terms
The word “sill” itself is a funny one. What the heck IS a sill anyway? Well, I looked it up for ya . . . and here’s a few ways it’s not-so-clearly explained:
- The bottom horizontal member of a wall or building to which vertical members are attached. (Wikipedia)
- The bottom of a system, window, door, framing member. The sill is a common reference for the last member prior to the ground or the support structure below. (builder-questions.com)
- The lowest horizontal element of a structure or body. (designingbuildings.co.uk)
- Heavy timbers that are notched to receive the vertical wall posts as well as the floor beams or joists. (hunker.com)
So the things I am picking up in these definitions are as follows:
- Sills are construction parts for buildings. Uh-huh . . .
- We are talking about something laying horizontally. Ok . . .
- It’s at the bottom or close to the ground. Got it . . .
- They are probably made out of wood even though only one place said that. Go on . . .
- Vertical things are attached to it. Super . . .
Super clear as mud maybe, but anyway it’s a start. As we explore the different kinds of sills on a pier and beam home, at least we know that all of them are probably made of wood, horizontally laid near the bottom of a home, and vertical bits will be attached to them somewhere.
What Are Sills Typically Made Of?
Most often a sill is made of pressure-treated pine boards or beams. Most commonly they are 4” x 6” beams. Sometimes, sills are made from doubled-up 2” x 6” or 2” x 10” boards. Whenever repairs are done with sills, the best practice is to match materials and use the same sizes that were original to the home.
Using a material besides wood, like steel I-beams or something, isn’t that cost-effective and won’t work any better than wood. So even though steel is strong and could do the job similarly, it’s also expensive and not really worth it. Better to use something inexpensive and easy to replace/repair if something goes wrong.
Using something other than wood could also add time to repairs just to figure out how to incorporate and attach things to it. Again, not worth it.
4 Types of Sills Found on Pier and Beam Foundation Homes
Ok, we are excluding window sills now, just FYI. So within the structure of a home’s foundation, 4 types of sills can be found. Here’s the shortlist:
1. Main Sills
2. Shaker Sills
3. Mud Sills
4. Sleeper Sills
I can’t wait to hear about the sleeper sill because I am hoping I can take a nap on it after reading this article, but I digress . . . Let’s check out each one in more detail now by learning about the location and purpose of each sill type.
1. Main Sills
The main sills are essential to the original structure of a pier and beam or block and base home. Ya can’t build a house like this without them because it simply wouldn’t work and your house would not stay upright.
Main sill beams are put in at the time of construction and are key to the whole support system of a home. Main sills are placed around the perimeter of the home and under walls (especially under load-bearing walls) to allow for all framing to attach from the starting point of the main sills.
2. Shaker Sills
Shaker sills are usually not original to the construction of a home but are added later to remedy a problem. In this case, it’s shaky floors. So they are not structural, but they do help shaky floors to not be shaky.
Extra sills are added during repairs to fix shaky floors under the middle of rooms instead of under walls where the main sills are located. Shaker sills add support to sturdy floors and better distribute the load across the foundation. A shaker sill will look just like a main sill (same size, same appearance), it’s just the placement of it that differentiates it from a main sill.
3. Mud Sills
A mud sill is only used/needed on a pier and beam home, but not on a block and base home. A pier and beam home uses a continuous concrete (or sometimes brick) beam around the outer edge of the home’s footprint. The mud sill is typically a 2” thick piece of timber laid flat on top of that perimeter support beam.
This sill type serves as a transition between the concrete and the wood framing used for the rest of the home’s structure. So the vertical framing above the mud sill will attach to it as the home begins to primarily use wood in its construction.
Not only does the mud sill act as the transition to wood but it also helps to compensate for irregularities in the beam and somewhat protects the floor joists from rot. If something rots, it will likely be the mud sill first because it is closest to the ground. It’s easier to replace one mud sill than every single floor joist!
4. Sleeper Sills
A sleeper sill, unfortunately, has nothing to do with naps *sad face*, but also, fortunately, has nothing to do with terrorists. Yay!
A sleeper sill is not structural or original to a home but is added later for extra support of a heavy item inside the home. Sleeper sills are only added on a case-by-case repair basis when needed or desired.
You wouldn’t need a sleeper sill unless you had one of these heavy things in your home. Common home items that might need a sleeper sill installed underneath them are things like pianos, gun safes, waterbeds, and very heavy built-ins.
What Else Is There to Know About Pier and Beam Homes?
Now that you know all about the types of sills in pier and beam home foundations and repairs, ya wanna know about the piers now don’t ya? There are also quite a few different types of piers that a homeowner might find on their crawlspace-type home.
At Anchor Foundation Repair, we want homeowners to know everything they could possibly want to know about their foundation. That includes everything from recognizing the signs of foundation problems, to the cost of foundation repair, to explaining terminologies like sills and piers. We don’t have any secrets, well . . . except for how we got so gosh-darn funny and charming.
For more informative charm, we’ve identified 6 common types of piers we typically see on homes in our Central Texas area. Check out Pier and Beam Foundation Homes: What Types of Piers are There?