Multi Foil Insulation | MultiFoil Insulation

Welcome to the Multi Foil Insulation category at Insulation4Less, where we offer a variety of high-performance, space-efficient insulation solutions. This category features products from Thinsulex and YBS, each offering unique benefits to meet your insulation needs.

How multifoil insulation works

Multifoil insulation uses several low-emissivity reflective layers with insulating wadding or similar core materials. The reflective faces reduce radiant heat transfer when they face an appropriate air space, while the core adds its own thermal resistance. That is why a multifoil should not be judged by thickness alone. Its declared product resistance, the adjacent air spaces, timber bridging and the rest of the construction all affect the finished thermal result.

For Building Regulations work, use a calculation for the complete roof or wall rather than treating a single roll as having a U-value. U-value is a property of the complete build-up. The BBA certificates for TLX Silver and TLX Gold make the same point: the final U-value depends on the other insulation, timber arrangement and construction details.

TLX Silver vs TLX Gold: what is the difference?

Thinsulex Multifoil Insulation

Thinsulex range of multifoil insulation products is known for its exceptional thermal performance and durability. The TLX Silver and TLX Gold variants, both available in convenient 1.2m x 10m rolls, provide effective solutions for a range of applications.

• TLX Silver Multifoil: Ideal for use in walls, roofs, and floors, this product offers a blend of insulation and vapour control. Its reflective surface helps in achieving optimal thermal efficiency, making it a popular choice for both new construction and renovation projects.
• TLX Gold Multifoil: This premium option combines the benefits of insulation with a breathable membrane. It's particularly suited for roofing applications, as it helps in regulating moisture and temperature, enhancing the overall comfort and energy efficiency of your home. 

YBS Multifoil Insulation

YBS Insulation offers a diverse range of multifoil products, known for their versatility and ease of installation. These products are suitable for various applications, including roofs, walls, and floors.

• Superquilt Multifoil Insulation Roll: This all-purpose insulation solution is available in multiple sizes to suit different project requirements. Superquilt is renowned for its high thermal performance and flexibility, making it a great choice for both residential and commercial buildings.
• Breatherquilt Multifoil Insulation Roll: Specifically designed for roofing applications, the Breatherquilt combines insulation properties with a breathable membrane. This dual functionality makes it an excellent choice for projects where moisture control and thermal efficiency are paramount.

Which multifoil insulation do I need?

Choose by position in the construction, not by assuming the more expensive roll is automatically the higher-performing insulation. TLX Silver has the higher tested product R-value of these two rolls. TLX Gold costs more because it performs a different job: it combines a breathable roofing membrane with an insulating multifoil layer.

Is multifoil insulation any good?

Yes, when it is specified as part of a tested construction and installed with the required air spaces and sealed details. The useful advantage is not a claim that a thin roll magically replaces every thickness of conventional insulation. It is that multifoil can add continuous thermal resistance across rafters or studs, reduce thermal bridging and combine insulation with vapour-control or breathable-membrane functions.

TLX Silver, for example, has a BBA-tested product thermal resistance of 0.91 m²K/W. TLX Gold has 0.85 m²K/W and is specifically assessed as an insulating breather membrane for pitched roofs. Those are product R-values. They are not U-values for a finished roof.

Why air gaps and sealing matter

Reflective insulation needs the installation geometry used in its assessment. Compressing the material, omitting a required cavity or leaving joints open can change the thermal and moisture behaviour of the construction. Follow the current TLX installation detail for the exact roof or wall rather than using a generic foil-insulation detail.

For TLX Silver, the reflective layer is intended to face an air space in the assessed build-up. Joints, edges and service penetrations also need the specified sealing treatment where the layer is providing air and vapour control. For TLX Gold, installation is different because the product belongs on the outer side of the roof and is designed to allow moisture vapour to escape.

What are the disadvantages of multifoil insulation?

The main limitation is that performance is installation-sensitive. A reflective layer cannot be assessed fairly if the required cavity is removed, the roll is badly compressed or air leakage is left at joints. Multifoil is also not automatically a complete replacement for mineral wool or PIR. Many compliant constructions use it with another insulation layer.

The second limitation is product choice. Breathable and vapour-resistant multifoils are not interchangeable. Putting the wrong type on the wrong side of a roof can change moisture movement through the construction. TLX Silver and TLX Gold look similar on a product grid, but their intended positions are fundamentally different.

Frequently asked questions

Is multi-foil insulation any good?

Multifoil insulation is effective when it is used in a tested construction and installed to the manufacturer’s detail. TLX Silver has a tested product thermal resistance of 0.91 m²K/W, while TLX Gold has 0.85 m²K/W. The final roof or wall performance depends on the complete build-up, including air spaces and bridging.

Is multifoil better than PIR?

Neither material is universally better. PIR is a rigid board that provides high thermal resistance within a cavity. Multifoil is flexible and can form a continuous layer across rafters or studs while also providing product-specific moisture functions. Refurbishment roofs often combine both materials to manage depth, bridging and installation around awkward details.

What are the disadvantages of foil insulation?

Reflective multifoil is sensitive to installation detail. Required air spaces, laps, seals and product orientation must be maintained. Compressing the roll or leaving unsealed joints can reduce the intended performance. It also should not be assumed to replace all other insulation; many compliant roof and wall systems use multifoil alongside PIR or mineral wool.

What is the difference between TLX Silver and TLX Gold?

TLX Silver is a 30 mm reflective multifoil with a tested thermal resistance of 0.91 m²K/W and can act as an AVCL in assessed systems. TLX Gold is a 33 mm breathable insulating roof membrane with 0.85 m²K/W. Gold is intended above rafters, while Silver is used on the inner side of relevant constructions.

Can I use multifoil insulation in a loft?

Multifoil can be used in pitched-roof and loft-conversion build-ups where the chosen product has an assessed detail for that position. TLX Silver is suitable for pitched-roof systems when installed as specified. A cold loft insulated only at ceiling level is a different construction, so do not copy a rafter-level detail without checking the design.

Does multifoil insulation need an air gap?

Reflective thermal performance depends on the air-space arrangement used in the product assessment and U-value calculation. TLX Silver details use reflective cavities in relevant constructions. The required gap and batten arrangement vary by application, so follow the current TLX detail rather than assuming one universal cavity size for every roof or wall.

Can multifoil insulation be compressed?

Multifoil should be installed at the thickness and geometry specified for the assessed construction. Compression changes the core thickness and can remove the air spaces that contribute to reflective thermal performance. The TLX Silver BBA data separately reports a much lower resistance when compressed, which is why tight packing should not be treated as equivalent installation.

Is TLX Gold breathable?

TLX Gold is a breathable insulating membrane designed for pitched roofs. Its seven-layer construction allows water vapour to pass through, and the manufacturer states that its vapour permeability responds to humidity. It is intended for use above rafters beneath slated or tiled roof coverings, subject to the certified installation details.

Is TLX Silver a vapour control layer?

TLX Silver is assessed by the BBA as insulation and a reflective air and vapour control layer in relevant wall applications, and it is used on the warm side in assessed roof build-ups. To perform that function, joints, edges and penetrations must be detailed and sealed in accordance with the current manufacturer installation guidance.

Can multifoil insulation meet Building Regulations on its own?

Do not assume a single multifoil layer will meet the required thermal standard by itself. Compliance is assessed using the U-value of the complete thermal element. TLX Silver and TLX Gold certificates both show that the final result depends on the complete construction, and additional insulation may be required to achieve the project target.