Erecting a wall is a whole art involving certain techniques to ensure proportionate mixing of the cement, accurate alignment of bricks, and attractive finishing for a complete wall.
Pointing vs Repointing
Pointing is one of the inital techniques of the building process of the wall and is all about creating visible shaped joints among all the adjacent bricks. At the same time, repointing is repairing the damaged material to ensure fine pointing.
This blog gives a comprehensive guide on pointing and repointing. Before diving into the details of this blog, Let’s learn a few lines about mortar that lies as the base of pointing and repointing.
When is Repointing Necessary?
Visual Signs of Deterioration: Obvious signs of failing mortar joints, including cracks, gaps, or crumbling, indicate the need for repointing to prevent further damage.
Separation between Mortar and Bricks: Small cracks forming between the mortar and brick faces indicate weakening mortar bonds. These cracks are the way for moisture to enter and damage the structure.
Frost Damage: Moistened mortar expanding due to frost can lead to its disintegration over time. Repointing is necessary to restore the mortar’s integrity and prevent further damage.
Cracks Extending to Masonry: If cracks develop in the masonry itself, extending into the brickwork, repointing might be required. This involves reinforcing the joint with helical bars set in grout, followed by repointing.
Process of Repointing
Repointing is done by a symmetrical approach removing the dust and old mortar and then adding the new one with a fine press. The whole step is decried below:
The method of removing old mortar is called raking out. For a good repointing, the raking is done 2x deep the height of vertical joints. For instance if the joint heigt is 8 mm tall, the repointing depth will be 16 mm.
Ways of Raking Out
Earlier, raking was carried out using a chisel and hammer. Nowadays, we have modern instruments that help finish raking out timely, smoothly, and finely. Handheld and wheeled raking tools are common examples of these tools. Likewise, angle grinders can be used with fitted diamond blades and mortar rakes to speed up the raking-out process.
Key Points to Consider
- Raking out via machines creates considerable dust that can be collected via dust control and extraction facilities.
- Brushes are used to remove the residues of previous pointing, followed by washing of the joints to make a clear and suitable surface for the binding of the mortar.
Previously, the mortar was pressed by hand using a pointing trowel or any other tool. Modern machines like manual or air-powered pressure guns or electric-powered auger-fed systems are used. With the help of these machines, repointing can be done in a consistent manner.
Percent Composition of Mortar for Repointing
Generally, the ratio of mortar components for repointing purposes is as follows:
Portland Cement: 1 part
Lime: 1 part
Sand: 5½ parts
However, it can vary depending on the repointing conditions so that it is compatible to suit the wall.
Finishing the Mortar Joints with Variable Styles
It is necessary to press the mortar finely to give an even shape void of any space, ultimately giving better strength and similar density at all the joints. This shaping and finishing of joints is called “striking” or “ironing”.
There are many shapes and designs to fill the mortar joints. Some most common examples include:
Flush Joint: The mortar is levelled with the face of the masonry units, creating a smooth and uniform surface.
Recessed Joint: The mortar is set slightly back from the face of the masonry units, creating a shadow line that can add depth and visual interest to the wall.
Concave Mortar Joint: This joint is made using a joiting tool having curved shape. This joint is famous for its water-resistant penetration tight sealing.
Struck Joint: The mortar joint is slightly indented and then finished with a striking tool, giving it a concave appearance.
Raked Joint: A portion of the mortar joint is removed, leaving a shallow groove. This style is often used for a rustic or weathered appearance.
V-Joint: The mortar joint is shaped in a V or U form, adding texture and detail to the joint.
Process of Pointing
Pointing is a technical process that needs professional expertise for a nice completion:
- In the first step, a good key is created with a specialised instrument to rake out all the masonry joints (15–20 mm) on the masonry face.
- Loose mortar or dust is removed by brushes
- In the next step, clean water is poured to wet the joints and left for hours.
- Once the joints are prepared, they are filled with mortar. This pressing helps to make a taight seal of the mortar.
Pointing and repointing are the basis for the structural integrity and aesthetics of a wall. However, they demand the implementation of effective techniques and a carefully prepared mixture of mortar by some professionals.