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In this article we will explain the process of EWI and Silicone render.

In this particular job we used 90mm grey eps and we always try to use this as standard where possible. You’re paying for the process and the thickness of insulation makes a small part up of the cost overall but is the biggest factor to saving money on your bills and creating a warm home. More is more when it comes to insulation. For example if you were paying 10,000 to have your house done in 50mm you will likely only spend 10500 for the 90mm whereas at almost double the thickness the benefits will be substantial. Not all properties are suitable for thick insulation over factors play a part. Soffit vents, soffit depths etc where verge trims don’t necessarily make sense. Most things can be altered to suit. Pipe work can be extended which is the case on 90% of jobs, windows sills and verges where possible. Blocking soffit vents and stopping roofs breathing is a big no no though. This can cause big issues in a property and allow a property to sweat causing damp and mould. So sometimes you’re governed by these things in terms of thickness of insulation. In this particular job the soffit vents were covered and over fascia vents installed by the customer under advice from a roofer. This is only possible in certain situations though.

Step 1 – Assess the property

The first and most important step before starting a new job is to assess the current condition of the property and identify any potential issues or repair works. In this case we found the existing pebble dash render to be loose and failing. It looked good on first glance but as always, we do thorough checks before applying more weight to a property.

We then take down all down pipes, lights, hanging baskets etc and start to protect the property before hacking off. Fully Protecting your property is a huge deal to us and is key to a good job.

Step 2 – Prep Work

Once the hack off is complete, all walls are washed down to remove any dust to ensure our material has a good bond to the substrate. Using a laser level, we then attach the base rails around the damp course level using hammer fixings to make a solid base to start our insulation. Verge trims are also installed where necessary, ensuring these are fully sealed on the back and top. These are necessary in creating protection for the render to ensure no water can get behind or drip down the walls and stain them where sufficient overhang isn’t available.

At this point we cut and install new window sills, as with most EWI jobs the originals become too small and can no longer direct water away from the wall below. This also helps the render to not look bulky giving the impression the house was built like it rather than retro fitted.

Step 3 – The Insulation

We then stick the insulation in a brick bond pattern staggering the joints and making sure all cuts around windows are in solid pieces of board as these are known as stress areas. All joints are foamed and the walls are fully rasped flat to remove any bumps from the walls, the protective film on the boards is also removed during this process which helps the base coat adhere to the insulation.

This is such an important process that many companies miss out. There are many other benefits including minimalising the risk of any “pillowing” with the boards. It’s a time consuming and messy process but totally necessary and goes towards a better job.

Step 4 – Fixing and Beads

We then fix pins through each board so our insulation is both stuck and mechanically fixed and we and the customer know the boards are properly fixed.

We then make our final checks to make sure everything is fully protected before applying our beads making sure they’re all straight and level.

Step 5 – Mesh Coat

We then apply the mesh coat material at around 6mm thick to the boards before using a straight edge to ensure the walls are flat. We then bed the mesh into this coat overlapping each section with the last. This ensures the wall is fully covered and strengthens the wall overall.

Once the mesh coat has dried it’s time for one more check with the straight edge to make sure everything is ok before applying the second coat.

Step 6 – 2nd Coat

The second coat or skim coat is a thin coat just to cover the mesh. This ensures the mesh is towards the front of the system and therefore providing strength where it’s needed the most. This second coat is then flattened off left to dry before using our powerfloats to sponge off and diamond float the surface ensuring an overall flat and smooth base layer.

Once the base coat has fully dried a primer is then applied

Step 7 – Top Coat

Once the primer is dry, the silicone top coat is then applied in a colour of the customers choosing. It is applied to the grain size and floated using a plastic float to give a uniform, textured finish. In this particular case “gris Clair” was chosen. A light grey colour from the VPI colour chart.

Step 8 – Clean Down

After this has fully dried its time for a big clean down, we remove all of the protection, clean down the windows and soffits before jet washing the patio/driveways. We reinstate all of the pipe work, lights etc using only stainless steel screws to make sure nothing rusts down the new render. Our mastic man then comes round to the job seals all around windows/pipes leaving a nice clean finish before we hand over to the customer. A final walk round is then done with the customer to ensure they’re fully happy with what has been done before we leave.

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