Drywall Control Joints Explained
Drywall movement control has gotten complicated with all the joint placement requirements, building codes, and expansion concerns flying around. As someone who has installed control joints in every application, I learned everything there is to know about preventing cracks. Today, I will share it all with you.
What Control Joints Do
Probably should have led with this section, honestly—control joints deal with natural stress and movement in drywall assemblies. They provide controlled weak points where cracks can occur harmlessly rather than randomly across surfaces.
Why They Matter
That’s what makes proper joint placement endearing to us drywall professionals—it prevents unsightly cracking:
- Buildings naturally expand and contract
- Temperature and humidity changes cause movement
- Structural settling creates stress
- Control joints accommodate these movements
When Required
- Large wall or ceiling areas (typically over 30 feet)
- Where dissimilar materials meet
- At construction joints in underlying structure
- Per local building codes
Types
- Vinyl Control Joints: Most common, easy to install
- Metal Control Joints: More durable for high-traffic areas
- Paper-faced: Easier to finish with joint compound
Installation
- Plan joint locations before drywall installation
- Install control joint at planned break points
- Butt drywall sheets against joint flanges
- Tape and mud flanges per manufacturer instructions
- Leave gap at joint center for movement
Common Mistakes
- Omitting joints in large areas
- Filling joint channel with compound
- Improper alignment with structural joints
- Inadequate fastening of flanges
