When we think about insulation, most of us picture cold draughts and heating bills. But with summer temperatures rising – and hot spells becoming more common in the UK – it’s worth remembering that insulation can also help keep your home cooler when it’s warm outside.

These days, more and more people are asking us about overheating in their homes. From stifling loft conversions to bedrooms that feel like ovens, high summer temperatures can make it hard to stay comfortable – or even safe.

It’s not just about comfort. Once indoor temperatures creep above 24°C, the risk of heat-related health issues rises – particularly for older people, young children, and anyone with a heart or respiratory condition. And it’s not just in Southern Europe: UK homes are among the least prepared in Europe for extreme heat.

A clear picture of the problem

Take a look at the thermal image below. It shows the plasterboard ceiling inside an Oxfordshire home during a recent heatwave. With no loft insulation, the temperature on the ceiling shot up to over 50°C – with heat pouring into the rooms below.

That kind of invisible heat gain makes everyday life much harder – especially at night when you’re trying to sleep.

What about humidity?

Hot weather and high humidity are a bad mix indoors. When air is damp, it becomes harder for sweat to evaporate, making it much harder for our bodies to cool down. That’s why managing moisture is a key part of keeping homes healthy in the summer, too. Breathable insulation materials can help regulate indoor humidity, avoiding the trapped, stuffy feeling you often get in poorly ventilated homes.

Where can you insulate?

It’s not just about the loft. Insulating walls, roofs, and floors – especially in converted lofts or sun-facing rooms – can all make a big difference. And when done with the right materials, you’ll feel the benefit year-round.

How insulation helps in hot weather

Insulation works both ways. In winter, it helps keep heat inside. In summer, it slows the heat coming in – helping your home stay cooler for longer.

Natural materials like woodfibre do this particularly well. They have a high thermal mass, which means they absorb heat slowly and release it gradually. In practice, that can delay heat build-up inside your home by 8 to 12 hours – keeping things cooler during the day, and more comfortable overnight.

It’s one of the reasons we recommend natural, breathable materials. Independent tests show they outperform many plastic-based insulations in extreme heat. In fact, natural options typically have five to ten times the thermal storage capacity of synthetic ones – meaning they absorb and release heat much more slowly. That helps delay overheating and keeps indoor temperatures more stable, even during a heatwave.

Avoiding the rush to air-con

Sales of air conditioning units have surged in recent years – and with it, energy use and emissions. But natural insulation offers a lower-carbon, low-maintenance alternative to mechanical cooling. Get it right, and you may not need to plug anything in at all.

Real homes, real benefits

Ironically, most people come to us to stay warm in winter – but the bonus is often a cooler home in summer. One example we often showcase is a 1930s end-of-terrace house that went as far as wrapping the whole home in woodfibre and external wall insulation. The result? Year-round comfort, and a clear sign that good insulation works both ways. It’s well worth exploring our other success stories to see what’s possible.

Too hot to sleep? Let’s talk.

If your home’s too hot in summer and too cold in winter, you’re not alone – but there is a better way. We can’t fix it overnight, but we can help you plan ahead. Smarter upgrades can make your home cooler in summer, warmer in winter – and more comfortable all year round.

Want to find out what’s possible for your home? Give our friendly team a call on 0330 223 2742 (Monday to Friday) or message us – we’re always happy to schedule a chat.

---

Want to dig deeper?

We have more information about insulation on these pages:

Floor insulation : Uninsulated floors can let warmth escape and cold air creep in – especially in older homes with suspended timber boards. Floor insulation is a smart way to reduce draughts, lower energy bills, and make your home feel more comfortable all year round.

Loft or roof insulation : Up to a quarter of a home’s heat can be lost through the roof. Loft or roof insulation is a simple but impactful upgrade – improving comfort, cutting heating costs, and reducing your carbon footprint from day one.

Solid wall insulation : Many older homes have solid walls, which lose heat much faster than modern cavity walls. Insulating these walls from the inside or outside can significantly reduce energy use – but it must be done carefully, as part of a whole-house plan.

Cavity wall insulation : Filling the gap between your home’s inner and outer walls with insulation can cut heat loss by a third. It’s a powerful efficiency upgrade for the right home – but only when conditions are suitable and installation is professionally managed.