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Topcoat and Render – YouTube Series Episode 6

To run alongside our new YouTube series, we have a dedicated series of blogs detailing the processes described in the series. We will cover every single step of the installation process, from an unprepared substrate, all the way to the aftercare stage. This includes customer and system aftercare. The series is broken up into the following steps:

  1. Starter Track
  2. Priming
  3. Insulation, adhesive, and fixings
  4. Beading and verge trims
  5. Basecoat and mesh
  6. Topcoat (priming and rendering)
  7. Tips and aftercare
  8. Our other services

Episode 6 moves the focus onto applying the finishing layer to your system. The names often associated with this are topcoat or render. Topcoat ender comes in several forms, including Silicone Render or Monocouche Render. The final facade finish is crucial as it makes the initial impression. Whilst an EWI system adds significant value to your property, it must be sealed with a weatherproof coat.

Step 1 – Choose a topcoat 

In the past, a common way to achieve a smooth, clean finish to a property was to use Monocouche or Sand & Cement-based Render. Whilst this does work for render-only projects, even minor movement from the insulation can cause ugly cracks over time. Even if you avoid cracking, traditional render can still become stained and leave you with the same ugly finish. EWI Pro wants to improve the appearance of properties throughout the UK and one of the ways we achieve this is through our market-leading range of Silicone Render. 

Currently becoming more and more popular, our EWI-075 Silicone Render has several features that make it a preferable choice for finishing your EWI project. Firstly, the silicone-based formula has far better durability and enhanced flexibility, protecting your facade from cracking for years to come. Our Silicone Render is breathable yet also water-resistant, making it ideal to use with insulation projects. Finally, our silicone render comes ready to use and can be tinted in thousands of different colours. 

If you’re working on commercial properties requiring a high degree of fire retardancy, check out our EWI-060 Mineral Render. 

For those of you working on coastal properties and require maximum water protection, we highly recommend using EWI-077 Nano Drex Silicone Render – our most advanced silicone render which actively breaks down biological growth 

Finally, if you are rendering below the DPC, we would encourage you to consider using EWI-050 Mosaic Render, which is engineered to be waterproof and highly durable. 

Step 2: Check the weather forecast 

Like our basecoat range, silicone render must be applied in dry conditions between 5c and 25c Celsius. Any exposure to rain, snow, strong winds or even direct sunlight during application can cause a number of different problems with the application process. Hence, it’s worth waiting for a period of dry weather before starting. 

Step 3: Prime the basecoat 

Your basecoat should already be smooth and dry, but before we can begin applying topcoat over it, you must always prime the basecoat to enable the best possible adhesion. Our EWI-333 topcoat primer is a highly effective primer designed specifically for silicone render. The best part about this product is that it can be tinted in the same colour as your silicone render, which ensures the basecoat colour doesn’t bleed through. If possible, apply this primer 24hrs before you apply your silicone render to allow it time to dry. 

Step 4: Mix the Silicone Render 

When you are ready to start, it’s important your silicone render is stirred with a paddle mixer, especially if the bucket has been stored away for a while. This ensures that the silicone and the aggregates are evenly distributed throughout the product. If you are mixing multiple tubs, be sure to use a new bucket to prevent contaminating the mixture with dirt or dust. Other than that, silicone render requires no other activation or ingredient – never dilute the product with water. 

Step 5: Apply the Silicone Render 

We split the application into three steps:

  • Putting it on 
  • Scrapping it back 
  • Rubbing it up 

Firstly, we’ve got to put it on the wall. Then use a plastering scoop to pour out a portion of the material onto your hawk. You will require both a hawk and a trowel for the application.

Once you’ve used what’s on your hawk, it’s time to begin scrapping back what you’ve laid on. Our silicone render is applied at the same thickness as its grain size. If you’re using a 1mm grain size, you’ll need to put a 1mm layer on the wall. The best way to achieve your required thickness is to scrape your trowel across the wall and take off the excess render. 

Next, you’ll need to rub it up. The aim of this is to texture the render and remove the trail lines from your trowel. Use a plastic trowel and rub in a circular motion to move the grains around. You’ll find the render wants to stick to your trowel so be ready to take the excess off onto your hawk. Don’t wash your tools while you’re still working as this could leave water marks. 

Repeat this three-step process as you work along your facade. As you become more experienced, you might choose to rub up a whole section of wall at once, rather than as you go. Either way, don’t let drying times catch you out. Always remember Silicone render is an air-drying material so you’ll need to keep a wet edge until the entire facade is complete. In warmer temperatures, you might have less than 15 mins or less before it’s too dry to rub up. 

It can be a good idea to try and work ahead of the sun. Let it follow you around the property rather than following the sun around the property, otherwise, the sun will heat up the basecoat and cause the topcoat to dry more quickly. 

As you might have suspected, this process will likely take three people. One put it on the wall, another to rub it up and another to prepare the next bucket of render. Alternatively, if you are doing this regularly, you’ll likely benefit from using a spray machine. As with our basecoat range, the vast majority of spray machines on the market are compatible with our products. Although bear in mind you might need a thin coat to render an accessory kit. 

Step 6: Wait for Silicone Render to dry 

The drying time is entirely weather dependent therefore keeping an eye on the weather is crucial. Both temperature and humidity will affect the drying time but normally, we would expect silicone render to dry in 12-72 hours. Be aware of overnight temperatures as silicone render will not set at all in temperatures under 5 degrees. If you are facing colder temperatures, we would recommend using EWI-006 Render Accelerator, which works to speed up the drying time. 

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