Rapidmix Basecoat Render 25kg

Rapidmix Multifinish Render is a factory-produced cement-based coloured render formulated with selected raw materials. It includes additives to provide the stated adhesion, water-resistance and workability characteristics. The render is intended for external use on masonry substrates and can be applied as a dash receiver, roughcast coat, smooth finish or sprayed textured finish.

It can be applied onto a Rapidmix basecoat or directly onto blockwork and brick substrates following appropriate preparation steps, including priming and slurry coating where required.

Applications

The render is intended for use on basecoat, concrete blocks and bricks. It may be used to achieve:

• 4–6mm dashing coats

• Roughcast finishes

• 7.5mm smooth finish coats

• Sprayed textured finishes

The system may be applied directly to blockwork when the surface has been correctly primed or slurry-coated with cement and SBR, depending on substrate type.

Preparation

Substrates must be sound, clean, dry and free from adhesion-impairing materials. Shiny surfaces must not be used. Structural defects, particularly those presenting a moisture risk, must be addressed before application.

Where necessary:

• Water down very dry substrates to control suction.

• Apply a cement/SBR slurry coat to brick or lightweight block substrates.

• Include beads and expansion joints as required by substrate design and relevant standards.

Masking should be removed before material dries. Scaffolding must be independently tied to avoid obstruction during application.

Mixing

Each 25kg bag requires approximately 4–4.5L of clean water. Mixing should be carried out using a suitable paddle, pan mixer or concrete mixer. Mix for 2 minutes, allow a 2-minute standing period, then remix to activate additives fully.

Application Guidance

Dashing Coat (4–6mm)
Apply 4–6mm onto a brush-keyed basecoat. While still open, apply dashing aggregate to achieve uniform coverage. Aggregate may be lightly tamped to ensure bonding.

Smooth Finish (7.5mm)
Apply 7.5mm thickness using a stainless-steel trowel. Level and allow to pick up for 2–8 hours, then sponge-float to finish.

Sprayed Textured Finish
Apply 7.5mm as above, allow initial pick-up, then form the texture using controlled spray application. Texture is influenced by pump pressure, nozzle size and spray technique. Sample panels are recommended for approval before work proceeds.

The total render system thickness should be at least 15mm in moderate exposure zones and 20mm in high exposure zones.

Environmental and Weather Considerations

Application must not proceed if any of the following are expected within 24 hours:

• Frost

• Rain

• Relative humidity above 95%

• Temperatures below +3°C or above +25°C

• Direct sunlight on the elevation

• Substrate temperature below +3°C or at or above 30°C

Finishing, Cleaning and Storage

All tools must be cleaned with clean water immediately after use. Waste material should not enter drainage systems.

Bags are water-resistant and can be stored for up to 12 months if sealed.

Performance Data

• Reaction to fire: Class A

• Dry bulk density: 1650kg/m³

• Compressive strength: CS IV

• Adhesion: ≥0.2N/mm² (FP: B)

• Capillary water absorption: W2

• Water vapour permeability coefficient (µ): ≤15/35

• Thermal conductivity (λ10,dry): 0.61W/mK (tabulated mean value; P=50%)

Technical Data