Comprehensive Guide to Brick Pointing and Repointing
Brickwork is one of the most durable construction methods in history, but even the sturdiest walls require maintenance over time. The most common form of maintenance for masonry is repointing—the process of removing old, decayed mortar from the joints and replacing it with fresh material. Whether you are a homeowner embarking on a DIY restoration or a professional contractor estimating materials for a large-scale project, our Pointing Mortar Calculator is designed to provide clinical accuracy in your planning.
Understanding the Basics of Pointing
Pointing refers to the finished appearance of the mortar joints in a brick or stone wall. Over decades, exposure to rain, wind, and freeze-thaw cycles causes mortar to erode. If left unaddressed, this erosion can lead to water infiltration, structural instability, and costly repairs. Repointing restores the weather-tight seal of the wall and preserves the integrity of the masonry units (bricks or stones).
It is important to distinguish between "pointing" and "bedding." Bedding is the initial application of mortar while laying the bricks. Pointing is specifically the outer layer of mortar that faces the elements. In repointing, we are essentially refreshing this outer layer to ensure it continues to protect the bedding mortar behind it.
Why Use a Pointing Mortar Calculator?
Estimating masonry materials is notoriously difficult because of the small volumes involved in hundreds of linear feet of joints. A slight miscalculation in joint depth or width can result in either running out of material mid-job or having dozens of unused bags occupying space on your property. Our calculator takes into account the specific dimensions of your bricks and the planned depth of your pointing to give you a precise volume measurement.
Key Factors in Mortar Estimation
Several variables influence how much mortar you will need for your project:
- Wall Area: The total square footage of the surface being repointed. This should include only the masonry sections, excluding windows and doors.
- Joint Depth: The distance you rake out the old mortar. Standard practice suggests raking back to a depth of twice the width of the joint (usually 1/2" to 3/4").
- Joint Width: The distance between the bricks. Most modern brickwork uses a 3/8" or 1/2" joint.
- Brick Dimensions: Smaller bricks mean more joints per square foot, which significantly increases the volume of mortar required.
- Waste Factor: Mortar is messy. A 10% to 20% waste factor is standard to account for droppings, tools, and mixing losses.
Types of Mortar for Repointing
Choosing the right mortar mix is more critical than the application itself. If you use a mortar that is harder than the bricks, the bricks will fail during thermal expansion. This is a common mistake in historic restorations where modern Portland cement is used on old soft-clay bricks.
1. Lime-Based Mortar (NHL)
Natural Hydraulic Lime (NHL) is the gold standard for historic masonry. It is breathable, allowing moisture to escape the wall rather than being trapped behind the surface. It is also flexible, "self-healing" small cracks through carbonization.
2. Type N Mortar
A medium-strength mortar (composed of Portland cement, lime, and sand) used for general-purpose above-grade applications on modern masonry. It offers a good balance of durability and flexibility.
3. Type S Mortar
High-strength mortar used for below-grade applications or load-bearing walls. Its high cement content makes it very durable but also very stiff, which can be detrimental to older structures.
The Repointing Process: Step-by-Step
Once you have used our calculator to order your materials, follow these steps for a professional-grade finish:
Step 1: Preparation and Cleaning
Begin by raking out the old mortar to the desired depth. Use a plugging chisel or a mortar rake. Avoid using circular saws if possible, as they can easily damage the edges of the bricks. After raking, clean the joints with a wire brush and spray the wall with water to remove dust and provide a damp surface for the new mortar to bond to.
Step 2: Mixing the Mortar
Mix your chosen mortar to a "thumbprint" consistency—it should hold its shape when squeezed but not be so wet that it slumps or runs down the wall. It is often helpful to let lime mortars "slake" or sit for a period before final mixing to ensure full hydration.
Step 3: Application
Work in small sections. Press the mortar into the joints in layers (lifts) of about 1/4 inch at a time. This prevents the mortar from sagging and ensures it is well-compacted within the joint. Fill the vertical joints (perpends) first, then the horizontal joints (beds).
Step 4: Tooling the Joints
Once the mortar has reached "leather hard" consistency (you can leave a thumbprint without mortar sticking to your finger), it is time to tool the joints. Common styles include flush, weather-struck, or recessed. Tooling compresses the face of the mortar, further increasing its weather resistance.
How to Calculate Mortar Volume Manually
If you enjoy the mathematics behind the masonry, here is the clinical formula used by our tool:
This formula calculates the total volume of the wall's face and subtracts the volume occupied by the bricks, leaving only the volume of the joints. We then multiply this by the depth and add the waste factor to arrive at your final estimate.
Standard Brick Sizes Reference Table
| Brick Type | Dimensions (Inches) | Joints per Sq. Ft (Approx) |
|---|---|---|
| Standard / Modular | 8 x 2.25 | ~6.75 Bricks |
| King Size | 9.6 x 2.6 | ~4.7 Bricks |
| Utility | 11.6 x 3.6 | ~3.0 Bricks |
| Roman | 11.6 x 1.6 | ~6.0 Bricks |
Pro Tips for Repointing Succeess
Maintain Moisture: Especially with lime mortars, keep the wall damp for several days after application. Use burlap sheets or a fine mist spray. This "curing" process is essential for the chemical strength of the joint.
Color Matching: Always do a test patch. Mortar looks much darker when wet than when dry. Mix small batches with varying sand colors or masonry pigments and let them dry completely before committing to the entire wall.
Temperature Control: Never repoint if there is a risk of frost within 48 hours. The water in the mortar will freeze, expand, and shatter the bond before it can set.
Conclusion
Repointing is a labor-intensive but rewarding process that can add decades of life to a building. By using our Pointing Mortar Calculator, you take the guesswork out of the logistics, allowing you to focus on the craftsmanship of the masonry itself. Plan accurately, choose your materials wisely, and your brickwork will remain beautiful and functional for generations to come.