Rendering or more commonly known external rendering is the use of an exterior plaster type finish generally applied to the façade and external walls of a building.
In traditional format render consists of a mixture of sand and cement that is applied to the outside walls of a building as a protective layer against the elements. It is critical when applying to blockwork and/or brickwork walls that the render mix is weaker than the substrate.
Modern day renders can contain silicone, minerals and acrylic compounds. Modern renders are flexible in their use and are more often than not used as a decorative façade finish.
Renders are often used as an integral part of a warm external wall system and can be applied directly to insulation boards or render carrier boards. A render system adds a viable insulation and waterproof coat to any building. These render finishes are often referred to as thin coat renders and many of the major manufacturers have regular training courses to help to learn the skill of successful application.
For those of you with competent trowel skills applying a thin coat render will probably come readily to you. Branching out into thin coat renders may suit your skill set or make a change.
Something to consider? Hey though – don’t forget, here in the U.K the weather isn’t always too kind so keep your options open.
Also, one of the potential problems of applying render is good access. Ensure you or your client has provided a safe means of access before tackling the job.
Here’s a quick guide to the application of a thin coat render – practise makes perfect and better still a certificate of competence from a manufacturers training scheme will help you perhaps find work and a better rate…
Apply the base coat in an even manner. Lay in the mesh reinforcement (don’t squeeze the mesh in too much) Over trowel the mesh with the basecoat ensuring it is flat and uniform, ruling off if required. There should be little evidence of trowel marks on the surface (a sponge may be useful) and the thickness should be flat and consistent.
Once the base coat is dry apply a coat of primer over the whole surface. Allow the primer to fully dry before tackling the top coat. Make sure you read the instructions on your top coating product.
Many manufacturers products vary so much – it’s best not to assume.
Take your top coat render and ensure it is properly mixed and prepared as the instructions. Apply the render using a steel trowel to a thickness around twice that of the aggregate size. Cover the elevation you are working on in full maintaining a wet edge. Return to the area for a second pass this time with an acrylic trowel and flatten the render removing the excess. This will reduce the top coat thickness to around the size of the aggregate used in the top coat mix. Aim for a consistent texture.
See if you can get the works passed, approved and signed off. If you’re a subcontractor this can only help when you produce your invoice and attach a copy of the sign off sheet.
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