Understanding Cement Brick Strength: What MPa Ratings Really Mean for Your Build

Author: Bertus van der Merwe

Date Published: 20 January 2026

First, let’s demystify MPa. An MPa (megapascal) is simply a measure of pressure or stress – in bricks it means compressive strength. In practical terms, it tells you how much load a brick can endure before it crushes. A higher MPa rating means a stronger brick. For example, a 7 MPa brick can withstand roughly seven million newtons per square meter of pressure in a crush test. As Apollo Brick explains, this test “determines how much weight or pressure a brick can withstand before failing”. In South Africa, bricks are categorized by strength – common grades range from about 3.5 MPa (used only for very light, non-structural work) up to 50 MPa for high-strength engineering bricks. In simple terms, think of the MPa number as the brick’s strength rating: a 14 MPa brick is literally tested to bear twice the pressure of a 7 MPa brick before breaking.

Typical MPa Requirements by Application

Choosing the right strength depends on how the brick will be used. In general:

• Single-storey homes (light load): Builders often use ~7 MPa cement (concrete) bricks for standard, single-storey residential walls. This meets the minimum SANS requirements for single-storey masonry.

• Two-storey homes or heavy loads: Ground-floor walls supporting upper storeys need much stronger bricks – typically 10.5–14 MPa. (Many contractors specify 14 MPa bricks for double-storey buildings.) This ensures the foundation and load-bearing walls aren’t overstressed.

• Boundary or free-standing walls: Garden or boundary walls not supporting floors use lower strengths. A 7–10.5 MPa brick is usually sufficient. (For example, free-standing external walls are commonly built with 10.5 MPa solid bricks or 7 MPa hollow bricks.) Thicker walls or higher walls might use 10.5 MPa bricks for extra safety.

• Foundations and retaining walls: These structural elements often require 10.5–14 MPa bricks as well. In very harsh or coastal environments (“severe exposure”), codes may call for the strongest classes (up to 21 MPa) for durability.

• Non-structural plaster or stud walls: If a wall is purely decorative or will be plastered, the minimum SANS standard is around 7 MPa (solid) or 3.5 MPa (hollow).

Always check project specifications: engineers and regulations (SANS 10400) determine the exact MPa needed. But as a rule of thumb, single-storey = ~7 MPa; two-storey or load-bearing = 10–14 MPa; very heavy or exposed = up to 21 MPa.

How and Why Bricks are Lab-Tested

Before any brick reaches your site, it should be rigorously tested in a lab. For compressive strength, the standard procedure is to soak and cure sample bricks, then crush them under a hydraulic press. In practice, labs take (say) five bricks, fill their frogs with mortar, cure them for 7–28 days, then load each brick between steel plates until it fails. The machine records the breaking force, and the brick’s strength (in MPa) is calculated as that load divided by the brick’s cross-sectional area. (For example, if a brick breaks at 10,000 N and its face area is 20,000 mm², its compressive strength is 0.5 N/mm² = 0.5 MPa.)

Testing isn’t limited to crushing. Good labs also measure water absorption and dimensional tolerance. South African standards (SANS 227 for clay, SANS 1215 for concrete units) specify maximum absorption and size variation. Apollo Brick notes that compliance testing checks that “bricks must meet … compressive strength” requirements, along with water absorption and size tolerances. Why does this matter? Because a brick that absorbs too much water or is out-of-size can weaken mortar bond or weather poorly, even if its MPa rating is high. At Khuthala Bricks, we test every batch of cement bricks in an accredited lab. Our QC process includes crush tests and absorption tests, so you see the actual MPa numbers on our certificates (not just a marketing label).

Why Certified Test Results Matter More Than Marketing

Not all claims are equal. In South Africa, the only reliable indicator of brick strength is an independent test or SABS certification. Masonry units that carry the SABS mark (SANS 1215) have been factory-tested to verify their nominal MPa class. As the Concrete Masonry Manual notes, concrete bricks without the SABS mark “should be checked at the frequency shown” (i.e. tested periodically). In other words, if a supplier can’t show you a SABS certificate or lab report, the proclaimed MPa is just a claim.

This is why we at Khuthala Bricks emphasize transparency. Every brick we sell is backed by lab data. In fact, a 14 MPa cement brick will perform identically to a 14 MPa clay brick – the material doesn’t matter, the number does. Cracking is almost always due to poor mortar or workmanship, not because a “cement brick” is inherently weaker. Always ask for the test report or SABS certificate. For example, our 7 MPa stock bricks have been tested to confirm they consistently exceed 7 MPa (with minimal variation), whereas some generic brands may only promise “7 MPa” in brochures but fail to prove it.

In summary, don’t judge a brick by its marketing. Trust the certified MPa rating. A well-tested 10.5 MPa brick is a 10.5 MPa brick, whether it’s labeled “high-strength” or not. At Khuthala Bricks, our MPA ratings are the actual outcomes of lab tests, so you build with confidence – not guesswork.