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How Often Do You Need a Brick Control Joint?

Published in Masonry Joints 4 mins read

Brick control joints are essential components in masonry construction, primarily serving to accommodate movement caused by thermal expansion, moisture changes, and structural settling. Precisely how often and where these joints are required depends on several factors, including the presence of openings in the wall and specific architectural features.

Understanding Control Joint Spacing

For straight runs of brickwork, the recommended spacing for control joints is typically based on whether the wall contains openings:

  • Brickwork with Openings: When your brickwork includes openings such as windows and doors, control joints should be spaced no more than 20 feet (approximately 6.1 meters) apart. These openings introduce stress points, making more frequent joint placement crucial to prevent cracking.
  • Brickwork Without Openings: For long, uninterrupted stretches of brickwork without windows or doors, the joint spacing can be extended slightly to 25 feet (approximately 7.6 meters).

Critical Locations for Control Joints

Beyond regular linear spacing, control joints are also indispensable at various other points within a brick masonry system to manage concentrated stresses and allow for differential movement. These strategic locations prevent localized cracking and ensure the long-term integrity of the wall.

Key areas where control joints are highly recommended include:

  • Adjacent to Wall Openings: Place joints vertically on both sides of windows and doors, extending from the foundation or floor line up to the top of the opening. They should be located within 12 inches (30 cm) of the opening.
  • At Wall Intersections and Corners: Both internal and external corners are significant stress points where perpendicular wall sections meet.
  • Below Shelf Angles and Lintel Beams: To allow for the movement of brick masonry panels supported by these elements, joints are needed directly below them.
  • Changes in Wall Height or Thickness: Wherever the wall profile changes, a joint is necessary to manage varying stress distributions.
  • At Pilasters and Columns: Joints are required on either side of structural pilasters or columns to isolate the main wall from their rigid elements.
  • Parapet Walls: Due to their exposure to extreme temperature fluctuations on multiple sides, parapet walls often require more frequent and carefully designed control joints, typically every 10 to 15 feet (3 to 4.5 meters).
  • At Junctions with Dissimilar Materials: Where brick masonry meets other rigid building components like concrete columns or steel frames, isolation joints are critical to prevent cracking from differential movement.

Summary of Control Joint Placement Guidelines

The following table summarizes general guidelines for control joint placement in brick masonry:

Feature / Condition Recommended Maximum Spacing or Placement
Horizontal Spacing
Brickwork with openings 20 feet (6.1 meters)
Brickwork without openings 25 feet (7.6 meters)
Specific Locations
Adjacent to wall openings Within 12 inches (30 cm) of each side
At wall intersections/corners Required
Below shelf angles/lintels Required
Changes in wall height/thickness Required
At pilasters and columns Required on each side
Parapet walls More frequent (e.g., 10-15 ft / 3-4.5 m)
At junctions with rigid elements Required

Why Are Control Joints So Important?

Brick masonry naturally expands and contracts due to:

  • Thermal Expansion and Contraction: As temperatures rise and fall, bricks and mortar expand and shrink. Without control joints, this movement can lead to excessive compressive stress, causing the masonry to buckle, crack, or spall.
  • Moisture Expansion: Bricks absorb moisture, which causes them to expand. This "moisture expansion" is a permanent, irreversible expansion that occurs over time.
  • Drying Shrinkage: Conversely, the mortar and concrete elements within the wall may experience some drying shrinkage, contributing to overall movement.

Properly designed and installed control joints absorb these movements, preventing uncontrolled cracking and maintaining the aesthetic and structural integrity of the brickwork. They are filled with flexible, durable sealants such as silicone or polyurethane, often over a backer rod, to ensure watertightness while allowing for movement.

For detailed guidelines and specifications, always refer to publications from reputable organizations like the Brick Industry Association and consult local building codes. Adhering to these recommendations ensures a resilient and long-lasting brick structure.