Types of Brick Mortar Joints in Masonry Construction

In masonry construction, the selection of mortar joints plays a crucial role in both the aesthetics and functionality of the structure. Mortar joints fill the gaps between bricks or blocks and provide stability, water resistance, and structural integrity to free-standing walls.

Each type of mortar joint offers a unique appearance and specific properties. In this article, we will explore the different types of brick mortar joints commonly used in masonry construction.

1. Struck Joint

The struck mortar joint is primarily used for horizontal joints and is not recommended for exterior masonry wall joints due to water seepage issues. In this joint, the bottom edge is recessed while the top edge is finished flat with the brick edge. The slope of the joint helps direct water away from the brick, making it suitable for interior walls.

2. Concave Joint

The concave joint is a popular choice due to its resistance to rainwater penetration and tight sealing properties. It is created using a curved steel jointing tool, which shapes the mortar into a concave curve. The concavity of the joint allows water to shed easily, minimizing the chances of water infiltration.

3. Weathered Joint

Weathered joints are commonly used for horizontal joints. These joints are designed to shed water away from the joint, preventing water movement through the underside. However, proper adhesion of the mortar is essential to avoid shrinkage cracks along the bond line.

4. Raked Joint

Similar to struck joints, raked joints are not suitable for exterior wall construction. This type of joint forms a ledge on top, which can trap snow, ice, or water. The space created by the core at the top of the brick unit allows water to penetrate the wall. Raked joints are best used for interior walls.

5. V Joint

V joints, characterized by their V-shaped groove, do not provide water penetration protection due to their geometry. Proper tooling of the V joint is crucial to prevent water accumulation within the groove and penetration into the brick. Careful attention should be given to ensure water resistance in structures using V joints.

6. Flush Joint

Flush joints are employed when the surface requires plastering or final finishing. These joints are designed to be hidden, as they are intended to be covered. Creating flush joints can be time-consuming and requires careful work to make them watertight and water-resistant. If the flush joint protrudes from the brick surface, water may accumulate on top, causing potential issues. Maintaining a consistent bond with the brick can be challenging when the mortar is not compressed into the joint.

7. Extruded Joint

Extruded joints do not require any tooling. Excess mortar in the joint naturally squeezes out and forms an extrusion between the bricks. However, extruded joints are susceptible to degradation when exposed to different weather conditions. Proper care must be taken to ensure the durability and longevity of structures with extruded joints.

 

The choice of mortar joint type in masonry construction is not only crucial for the visual appeal of the structure but also for its watertight properties and structural stability. Whether opting for struck joints, concave joints, weathered joints, raked joints, V joints, flush joints, or extruded joints, it is essential to consider the specific requirements of the project.

By understanding the characteristics and benefits of each mortar joint type, masons and architects can make informed decisions to create aesthetically pleasing, durable, and functional masonry structures.