Choosing the right insulation is one of the most important decisions in any loft conversion or home improvement project. It affects your comfort, your energy bills, and how much usable space you retain. SuperFoil multifoil insulation has become increasingly popular in the UK for good reason -- it delivers excellent thermal performance in a fraction of the thickness of traditional materials.
Here's everything you need to know before specifying insulation for your project.
What Is SuperFoil Insulation?
SuperFoil is a multifoil insulation product manufactured in the UK. It consists of multiple layers of aluminium foil and wadding that work together to reflect radiant heat, resist conducted heat, and minimise convective heat loss.
Unlike traditional bulk insulation that relies solely on trapped air pockets, SuperFoil combines reflective technology with insulating layers. The result is a thin, flexible product that can achieve thermal performance comparable to much thicker alternatives.
How Does Multifoil Insulation Work?
Multifoil insulation works on three principles:
Radiant Heat Reflection
The aluminium foil layers reflect up to 95% of radiant heat back toward its source. In winter, this means heat generated inside your home is reflected back inward rather than escaping through the roof. In summer, solar heat radiating through the roof tiles is reflected outward, keeping the loft cooler.
Conductive Resistance
The wadding layers between the foils resist heat transfer through direct contact. Each layer creates an additional barrier that conducted heat must pass through.
Convective Barriers
When installed with the recommended air gaps, the foil surfaces create still-air cavities that minimise convective heat movement. These air gaps are critical to achieving the stated thermal performance.
BBA Certification and LABC Registration
SuperFoil products hold BBA (British Board of Agrement) certification, which means they have been independently tested and verified for performance claims. BBA certification is widely recognised by Building Control officers, architects, and specifiers across the UK.
SuperFoil is also LABC (Local Authority Building Control) registered, which simplifies the Building Regulations approval process for your loft conversion. When your installer uses LABC-registered products and follows the approved construction details, sign-off is straightforward.
This matters because insulation is a key part of Building Regulations compliance. Using certified products removes ambiguity and avoids delays during inspections.
SuperFoil vs Traditional Insulation Materials
Compared to Mineral Wool (Glass Wool / Rock Wool)
Mineral wool is the most common insulation material in UK lofts. It's cheap and effective, but it has significant drawbacks in loft conversion scenarios:
- Thickness -- To meet current Building Regulations, mineral wool typically needs to be 250-300mm thick between and over rafters. SuperFoil achieves comparable performance at 40-60mm total thickness.
- Space -- In a loft conversion where every centimetre of headroom counts, the difference between 300mm and 60mm of insulation can determine whether a room feels spacious or cramped.
- Moisture -- Mineral wool absorbs moisture, which degrades its performance over time. SuperFoil is non-absorbent.
- Installation -- Mineral wool fibres can irritate skin and lungs during installation. SuperFoil is clean to handle.
Compared to Rigid Board (PIR / Phenolic)
Rigid board insulation like Celotex or Kingspan is a popular choice for loft conversions. It performs well but has its own trade-offs:
- Thickness -- Rigid board typically requires 100-150mm to meet regulations. SuperFoil is thinner still.
- Flexibility -- Rigid boards must be cut precisely to fit between rafters. SuperFoil's flexible nature makes it easier to install around irregular structures, pipes, and cables.
- Thermal bridging -- Rigid boards fitted between rafters leave the timber rafters themselves as thermal bridges. SuperFoil installed continuously over the rafters eliminates this issue.
- Cost -- Rigid board is generally cheaper per square metre, but the labour savings and space gains with SuperFoil can offset the material cost difference.
Ideal Uses in Loft Conversions
SuperFoil insulation is particularly well-suited to loft conversion projects for several reasons:
- Maximises headroom -- The thin profile means you retain more internal height, which is often the limiting factor in loft design.
- Continuous installation -- Fitting SuperFoil across the underside of rafters (rather than between them) creates an unbroken thermal envelope with no cold bridges.
- Vapour control -- SuperFoil acts as its own vapour control layer, reducing the number of separate materials and installation steps.
- Year-round comfort -- The reflective properties work in both directions, keeping the loft warm in winter and preventing overheating in summer. This is especially important for loft bedrooms on the South Coast, where summer roof temperatures can be intense.
Installation Best Practices
For SuperFoil to perform as certified, correct installation is essential:
- Maintain air gaps -- A 25mm air gap on each side of the foil is recommended for optimal reflective performance.
- Tape all joints -- Use SuperFoil's own foil tape to seal all overlaps and edges. This ensures the vapour barrier is continuous.
- Don't compress the product -- Compressing the layers reduces the insulating wadding's effectiveness.
- Ventilate correctly -- Ensure adequate ventilation between the roofing felt and the outer foil surface to prevent condensation.
Is SuperFoil Right for Your Project?
SuperFoil is an excellent choice for most loft conversions, particularly where headroom is tight or where you want the best possible thermal performance without sacrificing space. It's not always the cheapest option on a materials-only basis, but when you factor in the space saved, the reduced labour complexity, and the long-term energy savings, it frequently represents the best overall value.
At Better Lofts, we use SuperFoil insulation across many of our projects and can advise on the best insulation strategy for your specific property. Explore our loft insulation services or get a free quote to discuss your project with our team.
