Mastering the Art of Pointing: A Comprehensive Guide to Repointing Your Walls

Pointing, the process of filling and finishing the joints between bricks, stones, or other masonry units, is a crucial aspect of maintaining the structural integrity and aesthetic appeal of any building. Over time, the mortar in these joints can deteriorate due to weathering, erosion, and general wear and tear. This deterioration can lead to water ingress, structural weakening, and an overall unkempt appearance. Repointing, therefore, is not just a cosmetic fix; it’s a vital maintenance task that can significantly extend the lifespan of your masonry structures. This comprehensive guide will walk you through every step of the repointing process, from assessment to finishing, ensuring you achieve professional-looking results.

Why is Repointing Important?

Before we delve into the practical steps, let’s understand why repointing is so important:

• Structural Integrity: Deteriorated mortar joints compromise the structural stability of walls. They allow movement within the structure, potentially leading to cracks, bulges, and even collapse in severe cases.
• Water Ingress: Cracks and gaps in mortar joints provide easy pathways for rainwater to penetrate the wall. This can lead to dampness, mold growth, and structural damage from frost and freeze-thaw cycles.
• Energy Efficiency: Damaged joints can reduce the insulation effectiveness of a wall, leading to higher energy bills.
• Aesthetics: Crumbling mortar is unsightly and can detract from the overall appearance of a building. Repointing restores a neat and clean look, enhancing the curb appeal.

Assessing Your Walls

The first step in any repointing project is a thorough assessment of the wall. This will help you determine the extent of the work needed and choose the appropriate materials and methods. Here’s what to look for:

• Cracks and Gaps: Carefully examine all mortar joints for cracks, gaps, and areas where the mortar is missing or crumbling. Pay particular attention to areas near the ground, around windows and doors, and on exposed walls.
• Depth of Deterioration: Use a small tool like a screwdriver or a pointing trowel to test the depth of the deterioration. If the mortar crumbles easily or you can easily remove chunks with the tool, repointing is necessary. Generally, if the mortar has eroded to a depth of more than 10-15mm, it requires attention.
• Type of Mortar: Identify the type of mortar previously used. This is crucial for selecting a compatible mortar for repointing. In older buildings, lime mortar was common, while modern buildings tend to use cement-based mortars. Using an incompatible mortar can lead to problems later on. Lime mortars are softer and more flexible than cement mortars and allow the structure to breathe, moving slightly with changes in temperature and humidity. Using a cement mortar to repair lime mortar can be detrimental, as cement is harder and can cause the lime to crack and crumble.
• Efflorescence: Notice any white, powdery deposits on the wall surface. This is called efflorescence and is caused by soluble salts being brought to the surface by water. While not directly related to structural issues, it’s an indicator of moisture ingress, and repointing may help to alleviate it.

Tools and Materials You’ll Need

Before starting the repointing process, gather all the necessary tools and materials:

Tools

• Safety Gear: Safety glasses, dust mask, work gloves, and appropriate clothing are essential to protect yourself from dust and debris.
• Angle Grinder or Mortar Rake: For removing the old, deteriorated mortar (an angle grinder should be used with caution and appropriate safety equipment).
• Hammer and Chisel: For manual removal of old mortar, particularly in smaller or more delicate areas.
• Pointing Trowel (various sizes): For applying and shaping the new mortar.
• Brick Jointer or Profiler: For achieving the desired finish and creating neat joint profiles.
• Bucket: For mixing mortar.
• Hawk: A flat board to hold small quantities of mortar for easy access while pointing.
• Grouting Sponge: For cleaning excess mortar and the wall surface.
• Stiff Bristle Brush: For removing loose mortar and dust.
• Measuring Tools: Tape measure for checking depths and ensuring uniformity
• Bucket for water: for rinsing tools, cleaning and dampening the walls

Materials

• Mortar: Choose a mortar compatible with the existing mortar. For most modern brickwork, pre-mixed masonry cement is a convenient choice. However, if you’re working on a period property, opt for a lime mortar. Pre-mixed or hydrated lime mortar is readily available, though some may prefer to mix their own from scratch using hydrated lime and sand, ensuring correct ratios. For a softer mix, hydraulic lime can be used, but these tend to set faster.
• Clean Water: For mixing mortar and cleaning tools.
• Brick or Stone Dye (Optional): If you need to match the color of the old mortar, you can add a brick or stone dye to your mortar mix.
• Plastic Sheeting: To protect areas from dust and splashed mortar.

Step-by-Step Guide to Repointing

Now that you have your tools, materials and a clear understanding of the job you are undertaking, here is a step-by-step guide:

Step 1: Preparation

1. Clean the Wall: Thoroughly clean the wall with a stiff bristle brush to remove loose mortar, dust, and debris. If you have a pressure washer, you can use it to clean the wall, but be careful not to damage the brick or stone, and ensure the surface is fully dry before you start repointing.
2. Protect Surrounding Areas: Cover any surrounding areas you want to protect with plastic sheeting, as removing dried mortar can be a challenge. This includes windows, doors, patios and plants.
3. Dampen the Wall: Lightly dampen the wall with a sponge or spray bottle. This helps to prevent the dry brick or stone from sucking moisture out of the new mortar too quickly. If the brick is particularly porous or the weather is very warm, you might consider wetting the wall multiple times through the process. This will ensure the mortar can cure correctly.

Step 2: Removing the Old Mortar

Removing the old, deteriorated mortar is a crucial step for ensuring the new mortar adheres properly. The goal is to remove mortar to a depth of 2-2.5 times the width of the joint. This provides a good base for the new mortar. You can use one of several methods, or a combination, depending on the extent of the damage and the type of masonry.

1. Angle Grinder with Mortar Raking Disc: For larger areas and softer mortars, an angle grinder with a mortar raking disc is the most efficient method. Be sure to wear proper safety gear, including eye protection and a dust mask. Hold the angle grinder at a shallow angle to the joint and gently remove the mortar. Avoid pressing too hard or cutting into the brick or stone. It’s important to only rake out to the correct depth and not too far back, which can result in an unnecessarily wide joint.
2. Mortar Rake: A hand mortar rake is ideal for smaller areas and for fine-tuning the removal. Use a consistent motion, working methodically to rake out the old mortar. You may have to pass several times in harder mortars, or if the depth required is greater.
3. Hammer and Chisel: For more delicate areas, particularly on older or more fragile masonry, use a hammer and chisel. Hold the chisel at a shallow angle to the joint and gently tap with the hammer. Avoid using too much force, as you can damage the surrounding brick or stone. Carefully chip away the mortar. Take particular care around corners or reveals and always work along the length of the joint.

Tip: Be patient when removing the old mortar. It’s better to take your time and remove it cleanly than to rush and damage the surrounding masonry. Use a stiff brush to sweep away dust and debris.

Step 3: Mixing the Mortar

1. Choose your Mortar: Select the mortar mix that is appropriate to the job, whether that’s lime mortar, masonry cement or other specialist mix. Follow the manufacturer’s instructions regarding the required ratio of water to mix.
2. Add Water: Gradually add water to the dry mortar mix in a bucket while stirring with the pointing trowel or other mixing tool. Add small quantities at a time to avoid it becoming too wet.
3. Mix Thoroughly: Mix the mortar until it reaches a workable consistency. The mortar should be moist but not runny, sticking to the trowel but not dripping off. It should be a bit like a thick paste, or peanut butter.
4. Consistency Check: To test the consistency, place a small amount of mortar on your hawk. If it doesn’t slump or run, the mortar is ready. If it’s too dry, add a little more water. If it’s too wet, add a little more of the dry mortar mix.
5. Avoid Mixing Too Much: Mortar starts to cure as soon as water is added. If you don’t use it within about 1-2 hours you may need to throw it away. Don’t mix more than you can use in a reasonable amount of time, particularly on hot days when the mortar will cure faster. It’s always better to mix in smaller batches and refresh them regularly.

Step 4: Applying the Mortar

1. Load the Trowel: Scoop up a small amount of mortar onto your pointing trowel using the hawk or from the mixing bucket. It takes time to get used to the correct amount, which can depend on the width of the joints.
2. Push the Mortar In: Hold the pointing trowel at an angle to the joint, and push the mortar firmly into the joint using the trowel’s edge. Start at the back of the joint and work your way outwards ensuring there are no voids or gaps. It’s important to apply pressure to ensure there is a good bond between the existing surface and the new mortar. Don’t try to fill the whole joint in one go, build the mortar in layers or passes, especially in larger joints.
3. Overfill Slightly: Overfill each joint slightly, allowing for shrinkage as the mortar cures. It’s much easier to remove excess than try to fill small voids later on.
4. Work Methodically: Work in small sections at a time, completing a few joints before moving on. Avoid working in very large areas or trying to complete an entire wall at once, as this can result in inconsistent finishes.

Step 5: Finishing the Joints

Once the mortar has been applied, you need to finish the joints to create a neat and professional appearance. The type of finish you choose will depend on the style of your masonry and your personal preference. The mortar should still be workable when finishing. If the mortar is too wet or too dry, you will not be able to work the joint and achieve the correct finish.

1. Joint Tool: Use a brick jointer or profiler to smooth and shape the mortar. Run the jointer or profiler along the joint, applying even pressure to compact the mortar and create the desired profile. Various joint profiles can be used, such as:
• Flush Joint: The mortar is flush with the surface of the brick or stone. This is a common finish for modern buildings and provides a simple, clean look.
• Recessed Joint: The mortar is recessed slightly below the surface of the brick or stone, creating a shadow effect. This is often used in older buildings and is good for areas that are exposed to weather.
• Weathered Joint: The mortar is sloped away from the top of the joint. This is primarily used for weather protection and to avoid rain sitting on the wall and being absorbed by the brickwork.
• Bucket Handle Joint: The mortar is finished with a curved, concave profile that looks like it was created using the edge of a bucket handle. This finish is common in period properties.
• V Joint: The mortar is finished with a triangular, v-shaped joint. This style is also common in period properties and helps to add definition to the wall.
2. Consistency: When selecting the correct tool for the finish, consider the consistency of the mortar at the time of finishing. If the mortar is a bit wet, you may need to use a shallower tool. A drier mix will benefit from the more pronounced and deeper profile.
3. Brush Excess: Once you’ve finished shaping the joints, use a soft brush to remove any loose mortar or debris from the surface of the brick or stone. Brush away from the joint to avoid pulling material out of the freshly laid mortar.

Step 6: Cleaning and Curing

1. Clean the Wall: Use a damp sponge or brush to clean any remaining mortar from the surface of the brick or stone. Do this gently and avoid using excessive water, as this can wash the mortar out of the joints, particularly in lime mortars. Work lightly and patiently to remove stains and excess material.
2. Curing Time: Mortar needs time to cure properly. This can take several days, depending on the type of mortar, temperature, and humidity. Keep the newly pointed areas damp during this time by gently spraying with water, especially in hot, dry conditions.
3. Protect from Weather: If the weather is very hot, sunny or wet, protect the repointed wall by covering it with plastic sheeting or hessian.
4. Final Inspection: Once the mortar has cured, inspect the wall for any inconsistencies or defects. If you spot any areas that require further attention, carefully re-point.

Tips for Success

• Work in Small Sections: It’s easier to manage smaller sections and achieve consistent results.
• Don’t Rush: Take your time and focus on each step. Rushing can lead to mistakes and an inferior finish.
• Practice: If you’re new to pointing, try practicing on a less visible area of the wall first.
• Match the Existing Mortar: If possible, use the same type and color of mortar as the existing joints to achieve a seamless appearance.
• Seek Professional Help: If you are not confident in your abilities, it is always best to seek professional help, especially for extensive or structurally significant repointing projects.
• Weather Conditions: Avoid repointing in freezing temperatures or very hot and sunny weather, as this can affect the curing process.
• Consider the Mortar Type: Lime mortar needs to cure slowly and should not be re-pointed in damp conditions, as it will not cure properly. If using lime mortar, research thoroughly and mix correctly.

Conclusion

Repointing is a valuable skill that can significantly improve the condition and longevity of your masonry structures. By carefully following these steps and understanding the importance of each stage, you can achieve professional-looking results. While it may seem like a daunting task, with patience and attention to detail, you can successfully undertake a repointing project and ensure your walls are structurally sound and visually appealing for years to come. Remember to always prioritize safety and seek professional help when needed. Happy pointing!