Rendering a building’s exterior is a cost-effective way to improve its appearance. Rendering keeps moisture out and protects walls from weather damage. Customers and contractors prefer silicone render.
It has drawbacks. This article discusses silicone render selection and use.
Silicone Render Drawbacks
Silicone rendering is transparent, coloured, flat, and water-resistant. This may have major drawbacks.
Silicone render downsides:
- Needs warmth
- Patching difficult
- No colour change
Details are below.
Silicone render is laborious and slow. To prepare the wall for render, a basecoat must be applied. After 48 hours, apply a primer for the silicone topcoat. A plastic float smooths and thins the topcoat.
The silicone top-coat should match the render’s grain size and be applied in one coat to each section of the wall to avoid patches or lines where the render was joined in stages.
The entire process can take up to four days, making renovation budget management difficult.
Silicone render can be applied in wet weather, unlike sand and cement, but it has drawbacks.
Cold temperatures prevent silicone rendering. Because water in the solution cannot evaporate below 50C, the render will not set. It can stay wet on the wall and freeze. Render may crack.
If heavy rain accompanies cold temperatures, the silicone may wash off, leaving a poor finish.
Rendering silicone between October and March in the UK is risky due to low temperatures.
Silicone render costs more than sand and cement or monocouche render but less than external wall insulation.
Location and contractor determine costs. Silicone render is typically 10-15% more expensive than monocouche render and can cost more than double a sand and cement mix.
Silicone rendering is more expensive than other finishes because it moves with the building and doesn’t crack.
When choosing a render, consider whether the much more expensive silicone finish is a good long-term investment.
Rendering silicone has a greater environmental impact than mineral-based renders.
Mineral-based renders impact global warming 10% less than silicone-based ones and water-based environments 30% less. So if you are looking to reduce your carbon footprint then this is not the right choice.
The silicone additive produces hydrogen-chloride, a dangerous substance, and many contractors are using sustainable construction methods.
In addition, the silicone additive’s low-toxicity can add up when used in large quantities.
Patching is Hard
Sand and cement renders with cracks can be repaired without affecting the property’s appearance. Silicone render is durable, but high-pressure jet-washers or cracking can damage it.
Silicone render is coloured with the render rather than painted on top like other renders. Damaged walls are hard to match.
The patch job will stand out if the colour is even slightly different. Without re-rendering the wall, this is expensive to fix.
Silicone renders don’t need to be painted like mineral renders because the colour is part of the finish.
If the colour is changed after the render is applied, this is a major drawback.
Painting over silicone is impossible, but painting over sand and concrete render is easy.
After silicone render is applied, changing the colour requires removing the finish and starting over, which is time-consuming and expensive.
Silicone render lifespan?
Silicone renders, especially with an adhesive base coat, last longer than other mixtures. Silicone rendering can last 15–30 years.
Render durability depends on several factors.
Render lifespan depends on property location. Weather is harsher on coastal and high-ground properties.
This is especially true of coastal properties where harsh storms whip in off the sea and damage house exteriors with wind, rain, and saltwater.
Any render is only as good as its contractor. Like any building project, contractor quality varies. Poorly applied render needs replacing sooner than good work.
Cleaning and maintaining a silicone render properly prevents cracking and other damage.
Silicone Render Benefits
Silicone rendering has advantages.
Silicone render is flexible and durable. It moves with buildings, preventing cracks and damage.
Silicone render’s smooth finish is easy to clean. A warm-temperature, low-pressure jet washer should keep the building’s fascia looking new for years without repainting.
The colour is part of a silicone render, so keeping it clean keeps the colour sharp.
Silicone render is durable when applied properly, making it a good long-term investment compared to other finishes.
Silicone renders last at least 15 years and often longer, making the extra cost worthwhile compared to replacing other renders every seven to 10 years.
If silicone render isn’t right for your property or development, other options have their own benefits.
Sand and cement render is inexpensive, hides poor brickwork, and is easy to repair.
It cracks easily, needs frequent re-painting, and isn’t as weatherproof as modern finishes.
Pebble dashing, also known as dry dash or wet dash render, is another inexpensive option that is easy to repair and looks good. Like sand & cement, it cracks and requires regular maintenance.
A water-resistant, low-maintenance, breathable coloured cement finish.
It has crisp colours. As the building moves, stone-based renders can crack.
Acrylic render, made with plastic, is flexible, crack-resistant, water-resistant, and cheaper than silicone render. Like silicone, it is environmentally unfriendly and less breathable than modern finishes.