How To Render
Surfaces
Proper surface preparation, mixing, and application techniques are key to applying render effectively. By following this comprehensive guide, you can ensure that your render application is successful and achieves the desired finish. Applying render involves three key steps: surface preparation, mixing, and application. Firstly, define your surface and its suitability and of render type you need:
- Brickwork
- FC Sheet / Blueboard
- Concrete and blockwork
- Painted surfaces
- Existing Render
- AAC (autoclaved aerated concrete) panels and blocks
- EPS (Expanded and extruded polystyrene walling systems)
Preparation
To prepare the surface for rendering, follow these steps:
- Clean off dust, oil, grease, and any loose contaminating materials or coatings (except paint)
- Use a primer if desired, but it will extend the drying time of the render
- Green concrete: Allow the surface to cure for 28 days before rendering
- Dense concrete: Dampen the surface to be rendered by brushing, sponging, or applying a light mist spray of water
- Brickwork & Blockwork: Ensure masonry and mortar are applied according to Australian Standard AS 3700 and fully cured. Dampen the surface if it is dry and porous to prevent rapid drying of the render
- FC Sheet/Blueboard: Refer to the sheet manufacturer's recommendation regarding suitability and fix and join according to the manufacturer's recommendation
- Existing Render: Ensure the existing render is sound and remove any loose or drummy parts. Dampen the surface if it is dry and porous to prevent rapid drying of the render
- AAC blocks: Install according to manufacturer's instructions, clean off dust, oil, grease, and any loose contaminating materials using a stiff brush. Apply 1-2 coats of DUNLOP MULTIPURPOSE PRIMER before applying the render
- EPS: Install according to manufacturer's instructions. Polystyrene panels are UV sensitive, so do not leave them exposed to direct sunlight for an extended period before applying the render. The installation of an alkali-resistant mesh is required throughout the first coat.
Mixing
Render can be purchased as a powder or pre-mix. For powders:
- Add clean water to a bucket
- Gradually add the render (as outlined in the Technical Datasheet) to the water while mixing with an electric mixer until the powder is dispersed into a creamy, lump-free consistency.
- Allow the mix to stand for the time recommended on the TDS, remix, and then begin applying.
Application
- Apply the render with a steel trowel, evenly spreading the mix over the surface
- A gauging Trowel for a professional finish
- After recommended time, depending on ambient and surface conditions, work can begin on the surface finish. The finish can be dense and smooth by using a wooden or plastic float or coarse and sandy by using a sponge to achieve the desired effect
- Subsequent Coats and Tiling Over Render
- A subsequent coat may be applied after a recommended time, depending on ambient conditions and application thickness
- To tile over render, the render must be applied at a minimum thickness as outlined in the TDS and have a sandy finish. Prime and apply tiles with the recommended adhesive for that type of tile
Drying Time and Post-Application
The recommendations will specify touch dry times and cure times Before application of a decorative finish or premium quality acrylic texture coat or paint, allow the render to cure. The cure time increases according to thickness of the render.
Application
Surface Preparation
Firstly, define your surface and its suitability and of render type you need.
Handy Hints
These products can only be applied to alkali-stable and water-resistant non-hydrophobic paints. Pre-painted substrates must be mechanically roughened or washed with a pressure cleaner to ensure loose or unstable paint is removed. Consult with the paint manufacturer if the paint is suitable to be rendered over.