What is thin-bed mortar laying?
Thin-bed mortar laying (known in Dutch as ‘arm steken’) is a bricklaying technique where the mortar is applied thinly or sparingly to the brick or block. The bricklayer applies only a thin coat of mortar instead of a full, thick layer. This is the opposite of full-bed laying.
When is thin-bed laying used?
Thin-bed laying occurs in practice with:
- Thin joints — with thin-bed adhesive mortar, the joint thickness is only 2–3 mm by definition
- Calcium silicate blocks — precision blocks are laid with a thin layer of mortar
- Aerated concrete — aerated concrete blocks (e.g. Ytong) are bonded with thin-bed mortar
- Repair work — when replacing loose bricks, thin-bed mortar can maintain the original joint thickness
Key considerations
- Adhesion — with thin-bed laying, good adhesion between block and mortar is essential; the surface must be clean and dust-free
- Even application — spread the mortar evenly over the entire surface to avoid voids
- Mortar type — use the correct mortar for the application; thin-bed mortar has a different composition from traditional bricklaying mortar
- Not too thin — too little mortar results in poor adhesion and can lead to cracking
Full-bed vs thin-bed
| Method | Mortar layer | Application |
|---|---|---|
| Full-bed | Thick, fully covering layer (10–12 mm) | Traditional brickwork with clay bricks |
| Thin-bed | Thin layer (2–3 mm) | Adhesive mortar with calcium silicate or aerated concrete blocks |
Related terms
- Bricklaying
- Mortar
- Joint
- Bond pattern
- Masonry
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