Can You Use 100 mm Brick as an External Wall of a House?

Chris Morris
1 day ago
2 min read

When it comes to house construction, brick is one of the most popular choices for strength, durability, and timeless appeal. A question that often comes up is:

“Can I build my house with just a 100 mm brick wall on the outside?”

The short answer: not on its own. While 100 mm brickwork has its place, it is not suitable as a stand-alone external wall for modern homes. Let’s look at why.

1. Structural Strength and Stability

A single 100 mm thick brick wall is not strong enough to withstand wind loads or carry the weight of floors and roofs. External walls need to be structurally sound and capable of resisting weather forces. That’s why most houses are built with either:

Double brick (two 100 mm leaves with a cavity in between), or
Brick veneer (100 mm brick outer leaf supported by a timber or steel frame).

2. Weatherproofing Concerns

Brick is porous, and a single 100 mm wall will allow moisture to pass through. Without a cavity or additional barrier, water can easily penetrate the wall, leading to dampness and damage inside the home.

Modern construction methods use a cavity or a secondary structure to keep the interior dry.

3. Insulation and Energy Efficiency

A 100 mm brick wall has very poor insulation value (around R 0.18). On its own, it won’t meet today’s energy efficiency standards.

In a brick veneer system, insulation is added in the frame behind the brick.
In double brick, the air cavity helps reduce heat transfer and allows for insulation inserts.

4. Building Code Requirements

In most regions, building codes do not permit 100 mm brickwork as a free-standing external wall. However, using it as the outer skin of a cavity wall system is fully compliant and widely practiced.

The Best Options for External Brick Walls

If you love the look of brick, here are the two most common approaches:

Brick veneer: 100 mm external brick + structural timber/steel frame + insulation.
Double brick (cavity brick): 100 mm external brick + cavity + 100 mm internal brick.

Both give you the traditional brick appearance while meeting strength, weatherproofing, and energy standards.

Final Thoughts

A single 100 mm brick wall may sound like a cost-saving idea, but it’s not practical for external house walls. Instead, brick veneer or double brick construction provides the safety, durability, and energy efficiency required by today’s building standards—without giving up that classic brick look.