Beginner’s guide to render
Give your home the kerb appeal it deserves with the right choice of render. From traditional kinds to modern through-coloured systems, Anamika Talwaria sets out the options
It’s a popular choice for facade coverings, whether you’re building a new dwelling or updating an older one, so Anamika Talwaria explains how to get render right
Perfect for new builds and home renovations alike, a well-applied render finish can boost the look and value of your abode. With a range of colours, textures and materials available, this is a fantastic way to get the look you want or update a tired facade. But which solution is going to be right for you?
The basics
This cost-effective external wall finish is used to protect your home from weathering while simultaneously creating an attractive facade. The style you go for will depend on your personal tastes, as well as what might look good on the street scene as a whole.
Smooth finishes are popular for contemporary homes, but don’t rule out incorporating a bit of texture. This can be a simple but effective way to add a little character to an otherwise modern design. For example, including small flakes of aggregate in the base layer of a traditional cement render can create that textured look; or the top layer could be scraped before it dries to get the effect you’re after. And bear in mind that render can be used in conjunction with other cladding systems, like masonry or timber boarding, to create an appealing contrast.
In terms of installation, it’s best to speak to a specialist. “It is likely you will need to prepare your substrate,” says Kelvin Green, the facades product manager at Weber.
“For instance, a preparatory coat is advisable to achieve a good finish when you’re rendering onto smooth or otherwise unsuitable, but sound, surfaces.”
Most renders can be applied directly to solid systems like brick and block or insulating concrete formwork (ICF). If you’re working with timber frame or another lightweight structure, then you’ll need a carrier (backing) board. In all cases, the substrate must be free from any dirt, grime and organic growth before the render can be applied. “A preinstall inspection can allow us to specify suitable products and overcome any problems with the substrate,” says Andrew Rawsthorne, group technical manager at Ecorend.
Types of render
There’s a massive range of textures and materials available, from traditional lime-based products – perfect for period buildings – to modern silicone. The option you choose will depend on factors such as your budget, build system, whether you need a quick install and how much ongoing maintenance you’re willing to accept.
Standard cement
Conventional render is made up of cement, sand and water, mixed on site and applied in two or three coats. Each layer needs to be scored while still wet to provide a key (adhesive surface) for the next coat. The final finish is thinner and primed for painting (make sure you use a high-quality exterior grade paint).
Standard cement render generally needs repainting every 10-15 years to keep your home looking fresh. It’s also susceptible to developing cracks over time as your building expands and contracts due to changes in the temperature across the year. While this is the cheapest option in terms of raw materials, it does require more labour to install. It is also likely to end up more costly over time, due to the long-term maintenance required.
Monocouche
Relatively new to the UK, monocouche translates from the French for ‘single layer’. It’s a mineral-based render
consisting of one coat, applied in two passes (with the second added while the first is still tacky).
The big benefit of monocouche is that it’s throughcoloured, so you don’t need to paint it. And if the surface is scratched or damaged over time, the original finish will still show through. The hue is pre-mixed into 25kg-30kg bags, which are combined with water on site. Colour choices are limited, however. “As it’s mineral-based, bright and dark hues are not easily achievable,” says Kelvin. “Instead, this render offers more pastel and natural tones.”
The material costs are more expensive than standard render but monocouche is quick to apply, low-maintenance and durable, with a lifespan of around 60 years. It’s also more flexible than cement so it’s much less likely to crack over time. That said, it is still susceptible to the elements so requires some cleaning to make it last.
Silicone
Offering a super thin finish (just 8mm-10mm) and through-colouring, silicone render is a great choice for new build homes. These products are highly flexible and breathable, which means they are less susceptible to cracking. The silicone top layer is also water-repellent, which adds an element of self-cleaning to the finish – a light pressure wash every few years is all you need to maintain an appealing facade.
While it’s likely to cost around double the price of cement render to install, it offers greater longevity and minimal maintenance, so it’s great value for money. “Silicone is suitable for hand or spray application, but you must get a specialist in,” says Andrew. “The products are great, but poor installation can be a major problem.”
Silicone render is applied as a basecoat and primer before the through-coloured topcoat is applied. “We usually advise that you apply a fibre reinforcing mesh to stress points, such as around windows and doors, for best results,” says Andrew. “Keep in mind that adverse weather conditions can reduce the time window to complete the installation of the finish coat – it’s important to apply the coat in one go.” Build It opted for a silicone render by K Rend for the Self Build Education House, which was applied directly to our ICF structure. Find out more at www.buildit.co.uk/ourhouse.
Acrylic & polymer
These materials can deliver a thin layer to finish, that seals the structural fabric beneath. They come in a huge variety of tones and, as with other modern renders, are less prone to cracking than standard cement. One advantage of these solutions is that they’re available in a wider array of colours than some of the competition. They’ll create a durable and long-lasting finish, but are less breathable than silicone. Your render specialist should apply a basecoat in two passes and then add a primer and the finish, when dry, for the best results.
Traditional lime render
Heritage buildings were designed to breathe, allowing moisture to be absorbed and then evaporate. Standard cement renders do the opposite and instead seal the superstructure below. On a traditional property, this would lock moisture in and lead to damp and decay – so if you suspect cement render has been applied to your period home, it may need to be removed.
A permeable lime-based render is the best solution for older walls, allowing them to breathe as they were designed to whilst still protecting the fabric below. Lime renders are also flexible, so they won’t crack as your home moves over time, but they do require a specific skill set. The Society for the Protection of Ancient Buildings (SPAB) recommends contacting a professional familiar with this style of building and render so that you can be assured of a high-quality finish.
The render will need to be maintained with a fresh coat of lime wash every few years. It’s a little more expensive than your typical cement render, partly due to the need for specialist installation, but avoiding damp problems is priceless when it comes to heritage properties.
The Coloured Render Co Ltd are a family company with over 35 years’ experience in our field covering England and Wales.
We can advise on the best render system for your project, whether it is a traditional build or a modern method of construction system like SIPS, ICF, Durisol, Timber Frame.
We are also installers of insulated render systems and can offer U-value calculations for your project. Our team is made up of experienced professionals, not salespeople, and we are not committed to any one system.
All our work is guaranteed for 10 years and we have 1000s of colours available to choose from.
Contact us for information and pricing. 0845 319 4852 or info@plasterer.co.uk, also via our website www.plasterer.co.uk