What Are Control Joints in Masonry?
Control joints (also called movement joints) are intentional gaps placed in masonry walls that allow for controlled cracking. Brick, block, and mortar expand and contract with changes in temperature and moisture — without a designed place for movement, walls develop random cracks and structural stress. Properly spaced control joints absorb that movement, reduce cracking risk, and maintain a tidy finished appearance.
Why Control Joints Are Essential in Masonry
- Prevent cracking: Joints relieve internal stress by providing a controlled zone for expansion and contraction.
- Improve aesthetics: Keep cracks confined to joints so wall surfaces look uniform and professional.
- Extend structural life: Reduce long-term maintenance and avoid costly repairs caused by uncontrolled cracking.
- Enhance design flexibility: Integrate joints around openings, corners, and long spans without sacrificing appearance.
Where to Place Control Joints
Spacing depends on material and project size. Use these general guidelines:
- Concrete masonry (CMU): roughly every 20–25 feet horizontally.
- Brick veneer: roughly every 18–24 feet.
- Always include joints near doors, windows, and corners to relieve localized stress.
Note: Always confirm spacing with local codes or a structural engineer for your specific project.
Types of Control Joint Accessories
At Trowel Trades, we stock a full range of control joint products to make installation accurate and durable:
- PVC control joints — durable, affordable, and easy to install; ideal for brick, block, and stucco.
- Rubber control joints — flexible compounds that tolerate larger movement and vibration; great for exterior or high-temperature areas.
- Metal control joints — for precise profiles or where extra rigidity is required.
- Expansion joint fillers — compressible fillers that absorb movement and protect joints from debris and moisture.
Rubber vs. PVC Control Joints: What’s the Difference?
Both rubber and PVC joints control cracking and allow movement, but they differ in material properties and ideal use cases:
| Feature | PVC Control Joints | Rubber Control Joints |
|---|---|---|
| Material | Rigid polyvinyl chloride (PVC) | Flexible synthetic rubber |
| Flexibility | Moderate — suitable for standard movement | High — handles frequent or heavy expansion and vibration |
| Durability | Weather- and UV-resistant | Excellent resistance to UV, weather, and many chemicals |
| Best Used For | Brick, block, and stucco applications where clean lines are desired | Exterior, industrial, or high-temperature walls requiring maximum movement tolerance |
| Installation | Easy to cut and align | More flexible; may need careful placement for precise alignment |
Quick guidance: choose PVC for standard jobs where appearance and straightforward installation matter; choose rubber when you need greater movement tolerance or chemical/temperature resistance.
Tips for Installing Masonry Control Joints
- Plan ahead: lay out joint locations before you start masonry work.
- Keep joints clean: remove dirt/debris before sealing so movement isn’t impeded.
- Use flexible sealants: select a sealant compatible with your joint material that will stretch with movement.
- Match finishes: pick colors and profiles that blend with the masonry for a seamless look.
