Rendering over brick involves a multi-step process that prepares the surface, applies the material, and ensures a durable finish.
Rendering brick effectively transforms the exterior or interior appearance of a wall, providing protection and a smooth surface. Following key stages ensures proper adhesion and a long-lasting result.
Step-by-Step Process for Rendering Brick
Based on standard practices and the provided reference, rendering over brick typically follows these crucial steps:
1. Preparing the Surface
This is a critical first step for successful rendering.
- Key Action: As highlighted in the reference, begin by thoroughly cleaning the brick surface.
- Method: Use a steel brush to remove any paint, laitance, plaster, or any other loose material that may prevent good adhesion.
- Why it's important: A clean, sound surface is essential for the render to bond properly with the brickwork, preventing future cracking or delamination.
2. Mixing the Render
Proper render consistency is vital for application.
- Render can be a sand and cement mix, or proprietary pre-mixed products.
- Follow the manufacturer's instructions for pre-mixed renders or the correct ratios for site-mixed render.
- Ensure the mix is consistent and lump-free.
3. Applying the Render
This step involves applying the render onto the prepared brick wall.
- Apply the render in coats, typically a scratch coat followed by a top coat.
- The scratch coat is applied first and keyed or scratched horizontally to provide a mechanical key for the next layer.
- The top coat is applied after the scratch coat has cured sufficiently but is still green.
4. Finishing the Rendered Surface
Achieving the desired texture is done at this stage.
- Finishing can involve rubbing up with a float to achieve a smooth finish, or creating textured finishes like scraped, tyrolean, or roughcast.
- Ensure the surface is level and smooth before the render starts to set.
5. Curing the Rendered Surface
Proper curing is essential for strength and durability.
- Keep the rendered surface moist for several days after application.
- This can be done by misting with water or covering the surface with damp Hessian cloths.
- Curing allows the render to hydrate properly, achieving maximum strength and preventing shrinkage cracks.
6. Painting the Render
Once the render is fully cured and dry, it can be painted.
- Allow the render to dry completely; drying time varies depending on thickness, weather, and humidity.
- Choose an appropriate exterior paint, such as a breathable masonry paint.
- Apply paint according to the manufacturer's instructions.
Summary Table: Key Steps for Rendering Brick
| Step | Primary Action | Critical Detail (from Ref.) |
|---|---|---|
| 1. Surface Prep | Clean the brick wall thoroughly. | Use a steel brush to remove paint, laitance, plaster, or any other loose material. |
| 2. Mixing Render | Prepare the render material. | Follow mix ratios/manufacturer instructions. |
| 3. Applying Render | Apply render in coats (scratch coat, top coat). | Ensure mechanical key for subsequent coats. |
| 4. Finishing | Achieve desired surface texture. | Float or texture the surface. |
| 5. Curing | Keep render moist for proper hydration. | Mist with water or cover with damp cloths. |
| 6. Painting | Protect and decorate the cured render. | Apply suitable masonry paint after complete drying. |
Successfully rendering over brick requires careful execution of each step, starting with meticulous surface preparation as outlined in the reference.
