Mortar

Mortar Matters: The Unsung Hero of Masonry Construction

In the world of masonry, the focus is often placed on the beauty and durability of stone, brick, or block. But behind every enduring wall or timeless structure is a far less glamorous—but absolutely essential—material: mortar.

Mortar does more than simply hold things together. It plays a critical role in the performance, longevity, and resilience of any masonry system. Whether you’re building a new wall or restoring an old one, understanding mortar—and selecting the right type—is key to long-term success.

What Is Mortar Made Of?

Traditional mortar is a carefully balanced mix of sand, lime, and Portland cement. These ingredients are blended in varying proportions depending on the type of application, the materials being used, and the desired strength or flexibility of the mix.

The Three Key Functions of Mortar

1. Bonding

Mortar is what binds masonry units together—stone, brick, or block. A good mortar mix provides strong adhesion that supports structural stability while also allowing the wall to resist wind, gravity, and lateral forces.

2. Acting as a Sacrificial Element

In any masonry wall, there must be a material that gives slightly in response to movement, temperature change, or settling. That material should be the mortar—not the masonry unit. Mortar is meant to absorb minor shifts and stresses in the wall.
When mortar is too hard, it loses this sacrificial property. As a result, any movement in the wall gets transferred directly to the masonry unit—often causing it to crack, spall, or crumble. This is particularly problematic in heritage buildings or older bricks, which tend to be softer than modern materials.

3. Water Permeability

Moisture is an unavoidable part of masonry construction. Whether it enters through rain, condensation, or ground contact, water will find its way into and behind masonry walls.
One of mortar’s most important jobs is to allow water to escape—a process known as breathability or water permeability. When mortar is too dense or impermeable, it traps moisture inside the wall. If that moisture gets absorbed by the brick (or stone), it can freeze during cold weather and cause frost damage, leading to cracking and structural failure.

The Problem with Hard Mortars

Modern construction has made it easy to create mortars that are harder and stronger than ever—but this is often a liability rather than a benefit. When the mortar is harder than the masonry unit itself:

• It restricts movement, causing cracks in the brick or stone

• It traps water inside the wall, promoting freeze-thaw damage

• It overrides the natural balance of the masonry system

This is why it’s critical to match the mortar to the masonry, especially in restoration projects. Mortar should always be softer than the masonry unit, not stronger.

Why Lime-Based Mortar Is Often Best

For many projects—especially those involving older or heritage buildings—lime-based mortars are the preferred choice. They offer:

• Flexibility to absorb movement

• Breathability to allow moisture to escape

• Self-healing properties, meaning small cracks can re-seal over time

• A long history of compatibility with historic brick and stone

Lime mortars are naturally more forgiving, and they preserve both the look and performance of older masonry far better than rigid cement-based alternatives.

Always Choose the Right Mortar

Before starting any repointing or masonry repair project, it’s essential to understand the wall’s construction, the type of masonry units used, and the environmental conditions it’s exposed to. Only then can you determine which mortar mix is best suited to the job.

Whether you’re repairing a 19th-century farmhouse or building a modern garden wall, the right mortar makes all the difference in structural integrity, water management, and long-term durability.

Final Thoughts

Mortar may not be as visible or celebrated as stone or brick, but it is the unsung hero of every long-lasting masonry structure. At Solid Masonry, we take mortar seriously—evaluating each project carefully and selecting the appropriate materials to ensure performance, protection, and preservation.

Contact us today if you’re planning a masonry project or need expert guidance on selecting the right mortar for your home.