Baumit Base Coats for Lightweight Block / High Suction Backgrounds

Lightweight blocks and other highly absorbent masonry can draw moisture from freshly applied render too quickly. Without the correct preparation and base coat, this rapid suction can affect application, adhesion and the consistency of the finished surface.

This range includes Baumit products for preparing and reinforcing compatible lightweight blockwork and high-suction backgrounds. Baumit KZP 65 provides a lime-cement render that can be applied manually or by machine, while Baumit MC55 W is a fibre-reinforced, multipurpose bonding mortar. Baumit StarTex Fine mesh can be embedded within a suitable reinforcement coat where additional stability is required.

Products within this category can be used for:

• Preparing compatible lightweight blockwork
• Creating a stable base for subsequent finishes
• Improving adhesion between system layers
• Levelling suitable masonry backgrounds
• Reinforcing base coats with glass-fibre mesh
• Supporting hand or machine application

The correct preparation method depends on the block type, suction level and selected Baumit finish. Check the individual product data sheet before application and confirm whether the background requires wetting, priming, a bonding treatment or a reinforced base coat.

All surfaces must be sound, clean and free from dust, loose material and contaminants that could impair adhesion. Any movement joints, changes in substrate and vulnerable areas around openings should be detailed in accordance with the Baumit system specification.

Do not select a product solely because the substrate is described as lightweight or absorbent. Conduct a suction assessment where necessary and ensure that the base coat, reinforcement and decorative finish are compatible as a complete system.