Masonry leaf
A masonry leaf is one vertical layer of brick or block in a wall. Cavity masonry has two leaves with air gap; brick veneer has one leaf over a framed inner skin.
Ask Chalkline about this →A masonry leaf is one vertical layer (skin) of brick or block in a multi-skin wall assembly. The term distinguishes the structural layout: cavity walls have two leaves separated by a cavity, brick veneer has one leaf over an inner framed wall, full-brick or solid masonry has the entire wall thickness made up of leaves.
Three common wall assemblies in residential construction:
| Assembly | Leaves | Inner skin | Use |
|---|---|---|---|
| Brick veneer | 1 (outer leaf only) | Timber or steel frame | The volume residential default. Outer brick is non-structural; frame carries load. |
| Cavity masonry | 2 (outer + inner leaves) | Inner masonry leaf | Two masonry leaves separated by 50-75 mm cavity. Both leaves typically load-bearing under AS 3700. |
| Full-brick (solid) | 2 or more (no cavity) | The inner leaves themselves | Older heritage construction; rare in modern residential. |
Cavity masonry detail:
- Outer leaf: 110 mm brick. Weather-facing skin.
- Cavity: 50 to 75 mm air gap, kept clean of mortar droppings, drained at the bottom via weep holes.
- Inner leaf: 90 to 110 mm brick or block. Load-bearing.
- Wall ties: typically 600 × 600 mm spacing connecting the two leaves through the cavity. Type (light, medium, heavy duty) determined by wind class.
- Damp-proof course: at the base of each leaf, isolating from ground moisture.
Brick-veneer detail:
- Outer leaf: 110 mm brick. Non-load-bearing weather skin.
- Cavity: 40 to 50 mm typical, between the brick and the frame’s outer face.
- Inner skin: timber or steel frame; load-bearing.
- Wall ties: connect outer leaf to the frame studs at 600 mm horizontal × 450-600 mm vertical.
What the leaf does structurally:
- In cavity masonry, both leaves share gravity loads (in proportion to their stiffness) and the inner leaf carries the floor and roof loads. The cavity isolates moisture transfer but the leaves act as a system through the ties.
- In brick veneer, the leaf is non-structural: it carries its own weight to the foundation (typically a thickened slab edge or strip footing) but does not support floor or roof. The frame behind does.
- Wind load: in both assemblies, the outer leaf transfers wind load to the inner skin via the wall ties.
Why the distinction matters for builders:
- Engaging the right structural element: a fitting screwed into a brick-veneer leaf with no frame behind has minimal pullout strength. Use long screws into the frame, or chemical anchors to the brick if no other option.
- Penetrations: a hole through a brick-veneer leaf is just a hole through a non-structural skin. A hole through a cavity-masonry leaf may compromise load capacity; check with engineer for large holes.
- Failure modes: brick-veneer can debond from the frame (wall ties corroded, mortar bond failed, frame moved) and bulge or fall. Cavity masonry can fail differentially between the two leaves if the cavity is bridged.
Common defects:
- Cavity bridged: mortar droppings, sloppy wall ties, render-through-cavity all cause moisture to track from outer leaf to inner. Internal damp staining.
- No DPC at leaf base: rising damp into the masonry. Slow failure mode showing as efflorescence and salt-attack spalling at the base courses.
- Wrong wall-tie spacing: especially around openings where the spec calls for tighter spacing.
Also known as: leaf, wythe (US term), skin.
Category: Practical / masonry / wall systems.
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Last updated: 2026-05-14. Verified: 2026-05-14.