Thinking of painting your house a dark colour? Experts say there's something you should check first

Dark grey, charcoal and anthracite can give a house a sleek, modern look. It's easy to find a shade you love on a paint chart and imagine how good it will look on your walls. But choosing an exterior colour involves more than finding the perfect match for your windows, roof or front door.

There's a small detail on some colour charts that homeowners can easily overlook. Checking it before you start could help you choose a finish that's better suited to your home.

The problem with darker colours

Dark exterior finishes can absorb considerably more of the sun's energy than lighter ones. According to ArchDaily, citing facade manufacturer Sto, dark walls can absorb around 70–90% of solar radiant energy.

As the wall heats up, its materials expand. When temperatures drop, they contract again. Repeated changes can put stress on the exterior finish and contribute to problems such as cracking. Depending on the product and conditions, dark paint may also fade or require more frequent maintenance.

Walls that receive strong afternoon sunshine can be particularly exposed. West-facing walls are worth paying attention to, although the risk depends on the finish, the wall construction and how well the work was carried out.

The number to look for on your colour chart

Before settling on a shade, check whether the colour chart lists a Light Reflectance Value (LRV). This indicates how much visible light a colour reflects. In some European markets, including the Netherlands, a similar measurement is known as HBW.

The basic principle is straightforward: lighter colours reflect more light, while darker colours reflect less. White has a high reflectance value, while black has a very low one.

However, there's no universal minimum that makes every colour suitable for every exterior. The recommended value depends on the paint or render and the system beneath it. Some manufacturers also use Total Solar Reflectance (TSR), which takes more of the sun's energy, including infrared radiation, into account.

Baumit explains the considerations involved in choosing dark facade colours, while paint manufacturer Resene outlines how LRV works.

Why insulated walls need extra care

If your home has external wall insulation covered with render, it's especially important to check the manufacturer's recommendations. The render sits over insulation boards, and the outer layers can become very hot in direct sunlight.

Not every insulation and render system is designed to accommodate every dark shade. Choosing an unsuitable colour can increase the risk of damage over time. Bouwbestel explains why colour matters when insulating and rendering an exterior wall.

How to choose a colour more safely

You don't necessarily have to give up on a dark exterior. Some manufacturers offer special pigments designed to reflect more solar heat while retaining a dark appearance.

Before buying paint or render, ask the supplier or installer which shades are suitable for your wall. Check the product's technical guidance rather than relying on the colour chart alone. A slightly lighter shade may also be a sensible alternative.

Already have dark walls? Look for fine cracks around windows, corners and other edges. If you notice damage, ask a qualified professional to assess it rather than assuming the colour is responsible.

A dark exterior can still look great. Just make sure the finish you choose is suitable for the surface it's going on.