According to the provided reference, when insulation is placed in the air space of an exterior brick wall, the required clearance from the interior face of the brick to the exterior face of the insulation must be no less than a nominal 1 inch (25.4 mm).
Understanding the Air Space in Brick Walls
Exterior brick walls, particularly in modern construction, often serve as a veneer cladding rather than the primary structural element. A crucial component of a properly functioning brick veneer wall is the air space (or cavity) located between the interior side of the brick and the wall sheathing or insulation behind it.
This air space serves multiple critical functions:
- Drainage Plane: It acts as a pathway for water that penetrates the brick (which is porous) to drain down and out through weep holes at the base of the wall.
- Ventilation: It allows for air circulation, helping to dry out the cavity and prevent moisture buildup, which can lead to mold, mildew, or degradation of materials.
- Tolerance for Construction: It provides necessary space for masons to lay the brick accurately and facilitates the proper installation of flashing and other moisture management components.
Required Clearance with Insulation
As highlighted in the reference, a specific minimum clearance is necessary when insulation is installed within this air space.
| Component | Clearance Requirement |
|---|---|
| Brick Interior to Insulation Exterior | No less than a nominal 1 inch (25.4 mm) |
This nominal 1-inch (25.4 mm) clearance is vital even when insulation is present in the cavity to maintain the drainage and drying functions of the wall assembly. The insulation is typically installed against the sheathing, leaving the air space between the insulation and the back of the brick.
Maintaining this minimum gap is essential for the long-term performance and durability of the exterior brick wall system, ensuring it functions effectively as a drainage wall as intended.
