If you’ve ever been in an attic or a room with a sloped roof, you’ve probably seen a short wall that doesn’t quite reach the ceiling. That’s a kneewall! These short, vertical walls help support the roof’s structure and can create more usable space in what would otherwise be an awkward area.
This article provides a comprehensive overview of kneewalls: what they are, how they’re built, why they’re useful, and what you should keep in mind if you have them in your home.
What is a knee wall?
A knee wall is a short vertical wall, usually around 3 feet tall, that helps support a sloping roof or attic rafters. You might also hear these walls called stub walls or dwarf walls.
These walls are most often used to give structural support to the roof, especially in finished attics. Knee walls transfer the weight of the roof to the floor below, which is a pretty important job.
Knee walls also help to define a space, creating more usable square footage in attics and on upper floors. In other words, they can make an attic feel more like a room and less like a storage space.
Building and Installing Knee Walls
Knee walls can be made from different materials, including wood, brick, or concrete blocks. In residential construction, wood is the most common material.
- Wood is relatively inexpensive and easy to work with, but it can be susceptible to moisture damage and insect infestation.
- Brick and concrete blocks are more durable and fire-resistant, but they’re also more expensive and require specialized skills to install.
If you’re using wood, the knee wall will be framed with studs. The size and spacing of the studs will depend on how much weight the wall needs to bear.
The installation process involves framing the wall with studs and then attaching it to the floor and the rafters or trusses above. It’s essential that the wall is attached securely to maintain the structure’s integrity. Also, be sure the wall is properly aligned and level.
Remember to follow all local building codes as you build.
Benefits of Knee Walls
Knee walls aren’t just decorative; they offer several practical advantages.
Improved Stability
One of the most significant benefits is the enhanced structural stability they provide to the roof. They act as supports, preventing the roof from sagging or even collapsing, especially in regions that experience high winds or heavy snowfall.
Increased Usable Space
Knee walls also create more usable space in attics and on upper floors. By providing vertical walls, they make the area more comfortable and functional. The space behind knee walls can also be used for storage, although access might be limited.
Enhanced Insulation
Knee walls can significantly improve insulation and energy efficiency, especially if you insulate the space behind them. You can choose from various insulation options, such as fiberglass, spray foam, or cellulose, to maximize energy savings.
Things to Keep in Mind When Building a Knee Wall
When you’re building a knee wall, a few things are important. First, think about how tall and thick you want the wall to be. This will affect how much weight it can hold and how much space you’ll have inside the room.
Also, make sure the wall is attached securely to the floor and roof. You’ll need nails, screws, or bolts to do this.
Ventilation is also key. Without it, moisture can build up and cause problems. You can use vents or leave small air gaps to keep the air moving.
Don’t forget insulation! Insulation helps keep the room warm in the winter and cool in the summer. Seal any gaps or cracks to prevent air from leaking out.
Finally, remember that building codes for knee walls vary depending on where you live. Check with your local building department or a qualified contractor to make sure you’re following the rules.
Frequently Asked Questions
What is the difference between a knee wall and a cripple wall?
Okay, let’s break down the knee wall vs. cripple wall confusion. Both are short walls, but their purpose and location within a structure differ. A cripple wall sits atop the foundation and supports the floor joists, essentially raising the house off the ground. Think of it as the foundation’s little helper, providing a solid base for the floor above.
What is the difference between a knee wall and a cripple wall? (cont.)
A knee wall, on the other hand, is usually found in attics or rooms with sloped ceilings. Its primary job is to provide structural support to the rafters or roof. It creates usable space by preventing the roof from sloping all the way to the floor. It’s like a mini-wall that stops the roof from collapsing. So, cripple walls support floors from the foundation, while knee walls support roofs from the floor.
What is the difference between a knee wall and a cripple wall? (cont.)
Now, you might be wondering, “Can a knee wall also be a cripple wall?” Technically, no. Though both are short walls, their functions are distinct. However, sometimes the terms are used loosely, especially when dealing with complex architectural designs. But in general, remember cripple walls = foundation support, knee walls = roof support.
In Closing
Knee walls add structural support, create usable space, and improve insulation, especially in finished attics and under sloped roofs. If you’re thinking about adding or modifying knee walls, remember that proper construction is essential for safety and functionality. Take your time to consider all the relevant factors, and you’ll be well on your way to a successful project.