A cavity brick wall is a wall construction method featuring two separate brick walls (or skins) with a gap, or cavity, between them. This design is a common and effective way to provide insulation, prevent moisture penetration, and improve the overall performance of a building.
Understanding the Components of a Cavity Brick Wall
The basic components of a cavity brick wall are:
- Outer Leaf (Brick): This is the external wall, usually constructed of brick, providing aesthetic appeal and the first line of defense against the elements.
- Cavity: The space between the two walls, typically 50-150mm wide. This cavity acts as a thermal break and a barrier against moisture.
- Inner Leaf: This can be constructed from various materials, including brick, concrete block, or structural clay. It provides structural support to the building.
- Wall Ties: These are metal or plastic connectors that tie the two leaves together, providing structural integrity and preventing them from separating.
- Insulation (Optional): Insulation boards or materials can be placed within the cavity to enhance thermal performance.
- Weep Holes: Small openings at the base of the outer leaf allow any moisture that penetrates the outer wall to drain out, preventing it from reaching the inner leaf.
- Damp Proof Course (DPC): A waterproof barrier installed to prevent rising damp from the ground from reaching the wall structure.
Benefits of Cavity Brick Walls
- Improved Insulation: The air gap in the cavity acts as a thermal break, reducing heat transfer and improving energy efficiency.
- Moisture Resistance: The cavity prevents rainwater from penetrating the inner leaf, reducing the risk of dampness and mold growth. Weep holes ensure any water that does get through the outer leaf can escape.
- Sound Insulation: The double wall construction provides better sound insulation compared to a single-wall structure.
- Durability: Brick is a durable and low-maintenance material, contributing to the longevity of the wall.
How a Cavity Brick Wall Works
The outer leaf protects the inner leaf from the elements. Rainwater that penetrates the outer leaf is channeled down the cavity. Weep holes at the base of the wall allow this water to drain to the exterior. The cavity also minimizes thermal bridging, reducing heat loss in winter and heat gain in summer. Wall ties maintain the structural integrity of the wall.
Example:
Consider a house with a cavity brick wall in a climate with cold winters. The cavity, potentially filled with insulation, reduces heat loss from the interior, keeping the house warmer and lowering heating bills. The outer brick leaf protects the inner wall from rain and snow.
