Conventional, acrylic-based paints contain two potentially harmful components: volatile organic compounds (VOCs) and acrylic softeners. Both escape into the atmosphere during painting and for many years after application, contributing to greenhouse gases.
These toxic ingredients can also find their way into drains and groundwater when washing out brushes and disposing of paint tins in landfill. They can cause chest complaints, aggravate allergies and cause sick building syndrome.
Acrylic-based paints can also adversely affect walls. They prevent a wall from breathing, which can lead to moisture damage such as blown plaster.
Why use a breathable paint?
When we talk about paint breathability, we mean how much air and water vapour can easily flow through its surface. Older properties were built using materials that were designed to promote this airflow.
Using paint with a high level of breathability, coupled with breathable building materials, means that moisture doesn’t become ‘trapped’ beneath the surface of the paint.
Using a non-breathable paint can cause problems with the fabric of the building. Trapped moisture can lead to damp walls, causing the paint to bubble, peel and eventually blow completely. It can also contribute to a harmful living environment.
Paint breathability is measured in a couple of different ways:
The first is the Steam Diffusion (or SD) value. It is widely accepted that for a paint to be classed as breathable, it should have an SD value of one or lower. The lower the value, the more breathable the paint.
The other method used is the moisture vapour transmission rate (MVTR), which measures the amount of water vapour (in grams) able to pass through the paint surface over a 24-hour period. The higher the figure, the more water vapour that can pass through, and therefore the more breathable the paint. Check a paint’s datasheet to see if this measure is given.
High levels of VOCs generally are associated with oil-based paints, but they are found to varying degrees even in water-based paints. It is advisable to seek out paints containing a maximum of just 0.5g/L VOC.
The easiest way to ensure you’re creating a sustainable, environmentally-sound specification is to check the paint is Ecolabel approved. This stringent standard covers every aspect of a product’s manufacture, use and disposal.
Architects specify sustainability
When it came to building a new home for themselves, two partners in the practice Downs Merrifield Architects were determined to stamp sustainability throughout the specification.
Nic and Carolyn found the perfect plot for their home, close to the centre of Cardiff yet tucked quietly away in a leafy corner. Nic said: “We wanted the house to reflect our environmental principles, with a strong use of timber and energy-saving products. It was only natural for us to focus on sustainability of the build because that is the essence of our practice.”
Aiming to achieve high-quality design and Passivhaus status, Nic and Carolyn’s specification for the timber-framed, timber-and-glass-clad home includes very high levels of insulation, airtight construction, whole-house ventilation, photovoltaics and large areas of south-facing glazing to maximise solar heat gain.
Carolyn added: “We went to great lengths to ensure that our paint finish complemented the other sustainable aspects of the house. It was important to us that our choice was virtually VOC-free while offering high performance and excellent covering properties. The Ecolabel scheme offers environmental reassurance, so that was our starting point.”
The couple chose Earthborn because of its exceptional eco-credentials, low odour and hard-wearing finish. Every wall and ceiling that doesn’t have ceramic tiles or hardwood cladding has been painted with Earthborn.
Earthborn’s unique formulation is totally free of oils and acrylics and virtually VOC-free, and the result is a durable, anti-static, matt finish. Newly-decorated rooms can be brought back into use quickly because it does not give off any harmful emissions or odours.
Nic explains: “After living with white paint throughout the house for several months, we were ready to start choosing colours to enhance certain walls. It was great to move straight back into a room once it was painted, without worrying about any smells or emissions.”
Oak frame self-builder keeps it natural
When self-builder Joe Shimbart set out to build his dream home, he knew that he wanted to live in a house made of natural materials. He chose an oak frame with external walls constructed of environmentally-friendly hempcrete. This lightweight, breathable, insulating material is made from a mixture of lime and the shredded core of industrial hemp.
Speaking of his three-bedroom home in Hampshire, Joe said: “I didn’t want to wrap the oak frame in man-made materials, so I chose breathable hempcrete for the walls and finished them internally with lime plaster and a breathable paint. The breathability is essential – conventional ‘plastic’ paints seal the walls and don’t allow that.
“I always do a lot of research before making any specification choice. Earthborn’s Claypaint stood out because of its outstanding breathability and beautiful matt finish. It looks great on lime plaster, creating a warm, homely effect.”
Claypaint is a unique, clay-based emulsion. Its advanced technology maximises the natural properties of clay to create a high-performance, highly-breathable paint that covers exceptionally well and gives a distinctive, ultra-matt finish.
Joe added: “The lack of emissions meant I never felt nauseous when using the paint, unlike with acrylic paints in the past. In practical terms, it was easy to use. We only needed two coats to achieve full coverage and, because it is water-based, the brushes were easy to wash out.”