Temperatures hit the roof but a well-insulated one can help to keep you cool

During this heatwave, we’re on-site working in a room-in-roof setup where insulation has been fitted at rafter level using rigid PIR and Insulfix Track. Despite the high temperatures outside, this well-insulated space has become a popular spot among contractors for one simple reason: it’s significantly cooler than the outdoors!

We installed temperature probes and found that the temperature inside the insulated room-in-roof was a cool 22.4°C, almost 10°C lower than the outside temperature of 32.3°C. The tightly fitted insulation boards held in place by Insulfix Track insulation fixings create an airtight barrier, making it difficult for the outside heat to penetrate the space.

We often hear that insulation works both ways – keeping you warm in winter and cool in summer – and this experience confirms it. But with overheating on the rise, how can well-fitted rafter level insulation make a difference? Let’s explore further.

Understanding Solar Gain and Its Impact on Indoor Temperatures

One of the main contributors to overheating is solar gain, where sunlight heats up rooms through windows. When a house is insulated, this trapped heat can persist, leading to discomfort. While insulation sometimes gets the blame, it’s not the root cause. Minimising solar gain with shading, blinds, or curtains and ensuring proper ventilation by opening windows and vents for airflow can help keep indoor temperatures manageable. However, caution is needed during extreme heat, as hot outdoor air may further raise indoor temperatures, especially when there’s no breeze.

Thermal Gain from the Roof and How Insulation Can Help

When a loft is insulated at ceiling level with traditional fluffy insulation, it can feel like a sauna on hot days. Heat from roof tiles warms up the air in the loft, and without a cool breeze, ventilation may not make much of a difference. This hot air builds up in the loft and gradually warms the ceilings of rooms below. If the ceilings aren’t airtight, this heat transfer occurs more rapidly.

In contrast, when insulating at rafter level, you create a habitable space where temperature, humidity, and air quality are controlled. Here, insulation is positioned closer to the roof tiles and exposed to higher temperatures during hot weather. Effective insulation will slow down heat transfer, helping to keep your loft space cool – just as we’re experiencing on-site. However, if thermal bypass occurs due to gaps in the insulation, the outside heat will seep past, reducing the effectiveness of the insulation in summer and allowing cold air to escape in winter.

The Benefits of Rafter-Level Insulation Using Insulfix Track

Considering rafter-level insulation? Ensuring that your insulation is properly fitted and tightly secured will keep you warm in winter and cooler in summer. Independent tests showed that with traditional friction-fitted insulation, thermal performance in a test roof was 179% worse than expected. Using Insulfix Track insulation fixings to install insulation between rafters improved airtightness, achieving the desired U-value and thermal performance. Now that’s pretty cool!

For more information on how Insulfix Track can help you create an energy-efficient, comfortable home, please contact us today.