Masonry & Mortar: A Guide to Different Types of Mortar and Their Uses

Natural Hydraulic Lime cement mixed with a fine sand. This mortar was used to adhere pieces of historical limestone together while Lennox Masonry restored and rebuilt aspects of an old Gothic Cathedral.

Masonry, the age-old craft of building structures with carefully arranged stones and bricks, relies heavily on the use of mortar. Mortar serves as the binding material that holds bricks, stones, or other masonry units together, providing strength, stability and flexibility to the overall structure. In this blog post, we will explore the various types of mortar used in masonry and their specific applications.

1. Type N Mortar:

Type N mortar is a general-purpose mortar widely used in masonry construction by both professional masonry contractors and homeowners performing DIY tasks. Composed of a medium-strength mix of 1 part Portland cement, 1 part lime, and 5-6 parts sand, Type N mortar strikes a balance between strength and flexibility. It is suitable for a variety of applications, including interior and exterior above-grade uses. Here at Lennox Masonry, we use Type N mortar with fine sand for hard-brick chimney repointing and rebuilds, as well as thin stone and brick veneer projects. We use a coarser sand with Type N mortar when adhering stones together for above-grade retaining walls (depending on the type, size, and weight of the stone, we may utilize a Type S mortar mixture) as well as capping the walls, stone chimneys, outdoor stone fireplaces, etc..

A heritage-designated chimney in Victoria, BC which was rebuilt using Type N mortar.

2. Type S Mortar:

If a project demands higher strength and durability, Type S mortar is the go-to choice. With a higher proportion of Portland cement, consisting of 2 part cement, 1 part lime, and 8-9 parts sand, Type S mortar excels in heavy load-bearing applications. Here at Lennox Masonry, we commonly use it when constructing foundations for stone retaining walls, patios, chimneys, and any footer directly interacting with the ground which requires enhanced strength. As mentioned in our Type N mortar description, we may also use Type S for stone retaining walls and for capping purposes with a coarse sand, such as the stone walls, pillar, and staircase pictured below..

A stone staircase and pillar which was built by Lennox Masonry in Victoria, BC using Type S mortar.

3. Type M Mortar:

Type M mortar is the powerhouse of mortars, designed for projects where high compressive strength is crucial. However, it does not perform well when it comes to adhering masonry units which require a strong degree of flexibility. This mix, comprising 3 part Portland cement, 1 part lime, and 12 parts sand, is ideal for masonry foundations, below-grade structures, block walls, driveways, heavy-load-bearing walls, and areas subjected to heavy traffic. While Type M mortar provides exceptional strength, it is important to note that it is less workable than other types of mortar.

4. Type O Mortar:

On the opposite end of the spectrum, Type O mortar is the choice for projects that prioritize flexibility over strength. Consisting of 1 part Portland cement, 2 parts lime, and 9 parts sand, Type O mortar is suitable for use in historic masonry restoration, where a softer, more flexible mortar is necessary to accommodate the movement of older masonry structures. Lennox Masonry is based in Victoria, BC, Canada which is a region that is subject to low temperatures and plenty of rainfall. That being the case, we typically use Type O mortar for interior applications with stone and brick veneers where weather and low temperatures aren't a factor we need to consider.

A stone fireplace built by Lennox Masonry in Victoria, BC which utilizes several different mortar mixes including Type O.

5. Type K Mortar:

Primarily used for historical preservation and restoration, Type K mortar is the softest and most flexible of all mortar types. Comprising 1 part Portland cement, 3 parts lime, and 10 to 12 parts sand, Type K mortar is exceptionally soft and pliable. It is an excellent choice for projects involving fragile or antique masonry where minimal compression strength is required.

Limestone doorways from a 17th century Gothic Cathedral that Lennox Masonry restored and rebuilt as garden features in Victoria, BC.

Conclusion:

In the world of masonry, the right choice of mortar can make all the difference in the structural integrity and longevity of a building. Each type of mortar serves a specific purpose, addressing the unique demands of different projects. Whether you're constructing a load-bearing wall or restoring a historic structure, understanding the characteristics of various mortars is crucial to achieving a successful and durable outcome. As you embark on your masonry journey, consider the specific requirements of your project and choose the appropriate mortar type to ensure a solid foundation for years to come. And if you're unsure as to which mortar will suit your particular project requirements, reach out to your local masonry contractor such as Lennox Masonry in Victoria, BC for clarification.

Lennox Masonry of Victoria, BC has been proudly serving both Vancouver Island and the Gulf Islands for over a decade. We are small group of skilled masons with a great deal of passion towards our trade and for improving the communities we live and work in. We extend our gratitude to the lək̓ʷəŋən people for allowing us to share and work on this corner of the garden with them. We are thankful for the residents and businesses of Victoria, BC for supporting us in our endeavors!

If you’re in need of a professional and reliable masonry company for your next project, please contact us today!