Based on the provided information, it appears the question is referring to control joints in general, particularly as they relate to preventing cracking. The provided text does not specifically mention "frame control joints," but focuses on the broader category of control joints and expansion joints in building construction.
Therefore, we can rephrase the question for clarity and a more comprehensive answer: What are control joints, and how do they function in building construction?
Control joints are intentional grooves or cuts made in construction materials, such as concrete or plaster, to prevent cracks in finish materials by controlling where cracking occurs due to material shrinkage or expansion. They differ from expansion joints (also called construction joints), which reduce the effects of building movement on building materials and separate the building structurally.
Control Joints vs. Expansion Joints
To better understand control joints, it's helpful to distinguish them from expansion joints:
| Feature | Control Joint | Expansion Joint |
|---|---|---|
| Purpose | Control cracking in finish materials. | Accommodate building movement to prevent structural damage. |
| Function | Creates a weakened plane for predictable cracking. | Allows independent movement of building sections. |
| Building Impact | Primarily cosmetic crack prevention. | Structural integrity and prevention of major damage. |
Why Buildings Move and Need Joints
Buildings are dynamic structures and move due to various factors:
- Temperature Fluctuations: Materials expand when heated and contract when cooled.
- Live Loads: The weight of people, furniture, or equipment can cause deflection.
- Wind: Wind pressure exerts force on the building.
- Seismic Stress: Earthquakes cause ground movement and stress on structures.
- Deflection: Bending or sagging of structural elements under load.
Both control and expansion joints help mitigate the effects of these movements.
Practical Examples and Applications
- Concrete Sidewalks: Control joints are the lines you see cut into concrete sidewalks. These control where the concrete cracks, so the cracking is less noticeable and doesn't create tripping hazards.
- Large Plaster Walls: In large walls, control joints prevent unsightly cracks due to expansion and contraction.
- Brick Veneer: Control joints in brick veneer allow for expansion and contraction, preventing the brick from cracking or bowing.
In summary, while the term "frame control joints" isn't explicitly defined in the reference, the functionality likely alludes to general control joints which are designed to prevent cracking in finish materials by providing a predetermined location for stress relief. Expansion joints, on the other hand, manage the broader structural movements of a building.
