When taking on a masonry project – from building a retaining wall, repairing a foundation, or laying decorative brick – choosing the proper type of mortar can be the most important choice you’ll make.
Mortar is more than just a glue for bricks; it acts as both a structural component and an aesthetic component for your project, and will affect how long your masonry takes to wear in the future.
Type S and Type N are common mortars used in residential and commercial construction. Type S and Type N mortars may look interchangeable to the untrained eye, but there are differences between Type S and Type N mortars that make them unique advantages for different reasons.
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In this article, we investigate those differences, such as composition and compressive strength, as well as admixtures, costs, and ideal applications. By the end, you will know what type of mortar you need for your project, and why.
1. What Is Mortar and Why Does The Type Matter
Before starting part 2 of this article, it will be useful to understand in general what mortar is. Mortar is typically a mixture of portland cement, hydrated lime, sand, and water.
Its uses are for bonding masonry units – bricks, blocks, and/ or stones. However, mortar can vary greatly depending on its composition, and it can have different kinds of strength, flexibility, workability, and durability values.
That’s why choosing the right type matters: it affects both how easy the mortar is to work with and how long the structure will last under stress, environmental exposure, and settling.
2. The Basics: Type S Mortar and Type N Mortar
Let’s start with a broad comparison of the two.
| Feature | Type S Mortar | Type N Mortar |
| Compressive Strength | 1,800 to 2,300+ psi | Around 750 psi |
| Mix Ratio (C:L:S)* | 2:1:9 | 1:1:6 |
| Workability | Moderate; requires more effort | High; easier to apply |
| Weather Resistance | Excellent (good for below-grade) | Moderate (above-grade use) |
| Applications | Structural, load-bearing walls, slabs | General brickwork, non-load-bearing |
| Cost | Higher due to cement content | More economical |
| Admixture Compatibility | Yes | Yes |
3. Composition and Mixing Ratios
One of the primary differences between Type S and Type N mortar is their mixing. The ratios and materials have a direct effect on the performance of both types of mortar.
Type S Mortar
Type S mortar has a higher amount of Portland cement when compared to lime and sand. A commonly used formula would be as follows:
- 2 parts cement
- 1 part hydrated lime
- 9 parts sand
This combination yields a durable, dense mortar that has great compressive strength due to creating a finer grain, resulting in a tough product. The compressive strength of type S makes it the best choice for load-bearing, exposed to soil, moisture, or a high-impact area.
Type N Mortar
Type N mortar has a relatively neutral balance between cement and lime. This typically would be mixed as follows:
- 1 part cement
- 1 part hydrated lime
- 6 parts sand
Adding more lime to a mortar creates a creamier consistency than Type S, allowing it to be easier to manipulate. It allows the mason to spread, shape, and touch up while at work.
These qualities are why Type N is best suited for non-load-bearing applications, repair, cosmetic applications, or everything in between.
4. Strength Differences in Type S Mortar and Type N Mortar
Strength is the most pronounced technical difference when comparing both Type S and Type N.
Compressive Strength
The compressive strength of Type S mortar has a minimum threshold of 1,800 psi, but commonly achieves 2,300-3,000 psi depending on the exact formulation and curing processes.
Type N mortar, in contrast, has a compressive strength of around 750 psi.
This means that type S is utilized for demanding structural work.
Tensile Strength and Flexural Strength
Type S mortar has excellent tensile and flexural strength. That is, type S mortar resists cracking when subjected to tension and/or bending moments. For this reason, type S mortar is used for retaining walls or footing foundations, since both are subject to ground movement and load bearing.
Type N mortar’s structural properties may remain viable, but it is more suited to above-grade, cosmetic-oriented oriented and/or mild-duty projects. Examples of space include building facades, patio walls, or interior brickwork.
5. Admixtures: Improving Mortar Properties
Much of today’s mortar contains admixtures, or mixtures that are added to improve or modify mortar performance for unique structures. All types of mortar (type S or type N) can use admixtures, but for different effects.
The following are common admixtures:
Plasticizers – Support workability without increasing the amount of water introduced into the mortar.
Retaining agents – Slows down the drying of mortar on hot or windy days.
Accelerators or retarders – Change setting timing for cold or hot weather.
Bonding agents – Improve adhesion to masonry units or old mortar.
For type S mortar, common admixtures are often constructed for improving early strength gain or freeze-thaw ability; both are very important for footings and outdoor work.
Involving admixtures in Type N mortar focus mainly on workability, bond strength, and resistance to efflorescence—the white crystalline deposits that appear in some masonry.
Utilizing a well-chosen admixture can vastly extend the longevity of your structure and improve the ease of application, particularly where site conditions are challenging.
6. Where to Use Each Type: Practical Applications
Deciding between Type S and Type N is dependent on what you are building, where you are building it, and, importantly, where you are building it.
Type S Mortar Best Uses
Foundation walls – Where strength and moisture resistance are vital.
Retaining walls – When facing lateral pressure created by earth or water.
Sewer and stormwater structures – Maximum durability. Wet, corrosive environments.
Driveways and walkways – Where resistance to movement and mechanical wear is a must.
Masonry in exposed conditions (e.g., extreme weather, seismic zones).
Type N Mortar Best Uses
Above-grade brick veneer – Aesthetic walls and facades.
Interior brickwork – The best for applications with limited access or the need to work around complex detailed space.
Fireplaces – Moderate heat resistance with a simpler finish.
Patio walls and planters – Enough strength while being more adaptable to site conditions.
Restoration work – Exemplary selection for softer and flexible masonry evident in older buildings.
7. Workability and Ease of Use
A significant benefit of Type N mortar is how easy it is to work with. The additional lime in the mix results in a softer, creamier, more pliable mix. It is perfect for:
- Do it yourself (DIY) homeowners or novice masons.
- Projects that require significant detailing.
- Hot weather, because it allows for extended setting time.
Type S mortar, on the other hand, can be difficult to work with. It has a faster setting time, which can be challenging in warm conditions or for projects that require precision to set in detail.
That said, it offers the benefit of quick setting-and it is still strong when you need fast results and strong adhesion or work on repairs in cold weather.
8. Durability and Weather Resistance
In the durability and weather resistance categories, there is yet another disparity with Type S taking the lead.
Type S has outstanding resistances to freeze-thaw, erosion, and soil pressures, making it perfect for structures in contact with the ground, or in climates with higher variability.
Type N is sufficiently durable to live above-grade, under low-stress conditions.
When building in cold, wet, or southeast seismic zones, Type S mortar will provide you with lasting peace of mind.
9. Cost and Availability
In many cases, cost can heavily influence your decision on what material to use, especially for larger projects.
Often, Type S mortar is more expensive as a material, and due to the sanctity of its cement material, mixing process, and jump-start times, it may require more labor to apply.
Type N mortar is less expensive. It is cheaper to produce, easier to work with, and typically takes less labor time to apply.
But as mentioned, using the cheaper mortar when your project needs strength can be an expensive mistake.
If Type N is used where Type S was called for your masonry will likely experience early loss of performance that will require costly repairs.
Long-term durability trumps short-term cost savings.
10. Can They Be Interchanged?
In most scenarios, Type S mortar and N mortar should not be interchanged. They have very different strengths and formulations associated to very different tasks.
That being said, in some light-duty, non-load-bearing applications it may be acceptable to substitute Type N for Type S, so long as there is no load-bearing requirement and no risk of moisture.
When in doubt, consult a structural engineer or professional mason before looking to substitute.
Conclusion
The choice of Type S or Type N mortar may come down to semantics; however, it can significantly affect the durability and success of your masonry project.
Type S mortar provides strength and durability, and it is a great fit for structural and below-grade projects. Type N mortar, however, provides agility, ease, and cost savings on general-purpose and aesthetic masonry jobs.
By knowing how Type S and Type N mortar vary, in addition to how admixtures and strength aspects influence performance, you are better capable of delivering appropriate recommendations.
Always consider the specific demands of the project—whether it is through environmental condition factors, structural shortcomings, budget constraint(s)—and match the mortar to obtain the appropriate mix of strength, workability, and durability.
Frequently Asked Questions (FAQ)
1. What is the most significant difference between Type S and Type N mortar?
The most significant difference is compressive strength; Type S mortar is 1800-2300 psi, whereas Type N mortar is about 750 psi. Therefore, it is reasonable to conclude that Type S is an appropriate choice for structural work and below-grade applications, while Type N is a choice for above-grade or general purpose masonry.
2. Can Type S and Type N mortar be used interchangeably?
In general, the answer is no. Each is designed for different purposes and using them interchangeably could lead to catastrophic failure or would cause premature wear and tear on the structure. Type S mortar should be used where there is a need for higher strength or durability. For example, using Type N in place of Type S in a structural application could lead to concerns relative to safety and performance.
3. In what specific applications would mortar supply Type S over Type N mortar?
Type S mortar is preferable with medium or high-stress applications, or exterior applications that include:
1. Foundation walls.
2. Retaining walls.
3. Structures S exposed that will be exposed to wind and seismic forces.
Any project with exposure to moisture or soil when the mortar (and accompanying masonry cantilever) is very likely to experience an extreme moisture or freeze/thaw environmental exposure.
Because of its strength and durability, Type S is preferable for any application where either the masonry needs to support a load or where huge swings in moisture are likely.
Sandip Agrawal, Polymer Engineer and MD of Sakshi Chem Sciences Pvt. Ltd., leads innovation in construction chemicals, shuttering oils, and industrial lubricants. With expertise in polymer science and eco-friendly solutions, he drives R&D and sustainable advancements, ensuring high-performance products for India and global markets.