U-VALUE CALCULATOR

Meeting Building Control Approval With Multifoil in 2024

You may have heard that multifoil insulation won’t get building control approval or meet performance standards on its own. But is that true? Is Multifoil as controversial as the “internet experts” deem it to be?

The simple answer is no. Heat as a source of energy moves from a hot surface towards a cold surface to create a balance; which means that the main role of insulation is to minimise heat loss by delaying heat transfer as much as possible. However, it’s important to remember that there’s more than one way to slow the transfer of heat. Multifoil insulation is simply a type of insulation that is designed to make effective use of various materials, including reflective radiant barriers to provide protection against all three forms of heat transfer: conduction, convection, and radiation! On top of that, Multifoil offers a built-in vapour control layer (or breathable membrane) to prevent condensation and moisture ingress.

Do Multifoils Comply With Building Regulations?

Yes, Multifoils are fully compliant with Building Regulations. In recent years, building regulations in the UK have become stricter, with the current requirements demanding highly efficient insulation standards for various elements of a building. For instance, the current standard U-values for roofs in new builds stand at 0.11 W/m²K, for walls at 0.18 W/m²K, and for floors at 0.13 W/m²K. The great news is that Multifoil Insulation provides a great solution for improving overall thermal performance to help meet these higher U-values targets.

These regulations are somewhat more forgiving for retrofit projects, requiring U-values of 0.15 W/m²K for roofs, 0.18 W/m²K for walls, and 0.18 W/m²K for floors. However, that is only to reflect the difficulties inherent in improving the thermal performance of an existing property. 

Meeting these standards in retrofit projects can be challenging of all considering the fact that extensive modifications may not be feasible and the proposed u-values are traditionally difficult to achieve without such modifications. However, Multifoil insulation presents a potential solution to that issue… When installed to our recommendations – i.e. with counter battens to create a proper air gap and in a duet or hybrid system, Multifoil insulation is more than capable of meeting the requirements set out and provides the additional benefit of eliminating the need for extra vapour control or breather membrane products, bulky insulation, and unnecessary supporting structures. In fact, SuperFOIL offers several retrofit solutions that achieve building regulations without the use of traditional insulation materials. 

Furthermore, advanced multifoil products like SuperFOIL SF60 which are only 100mm thick are the highest performing multifoil products available in the market today. With this versatility and efficiency, Multifoil insulation is a perfect choice for meeting building regulations without compromising on performance or space requirements and people are beginning to realise just how ideal Multifoil is!

SF40 high performance multifoil insulation

Is Multifoil Tested & Certified To Today’s Thermal Performance Standards?

Modern-day Multifoils aren’t the same products the market saw in the 1990s, we’ve come a long way over the years and it shows in the advanced features now boasted by our Multifoil products.

Many of the products available today are manufactured using the most innovative technology, integrating many key features into a thin and efficient product. Born of the need to address the many issues that the insulation and construction industries are facing – thermal bridging, space limitation, building regulations requirements, and climate change to name a few.

To do so, they must be able to meet todays’ performance standards, which is why SuperFOIL’s Multifoil insulation products are tested to the latest thermal insulation test requirements for both ‘guarded hot plate testing’ (ISO 8302:1991) and a ‘heat flow metre testing’ (ISO 8301:1991) by KIWA BDA. 

All SuperFOIL Insulation products are independently tested by notified bodies and third party certified laboratories to comply with relevant UK building regulations for use as part of construction and European regulations such as CE/UKCA. The products are rigorously tested and examined to ensure they meet the standards at all stages and are manufactured to last as long as 50 years. We are also a part of the Quality Mark Protection scheme and the IAA, meaning you are protected when using SuperFOIL products in your project. If you’re interested to learn more, you can view all of our certifications for each product under our ‘Declaration of Performance’ documents on our website.

SuperFOIL Products Declaration of performance example

We have stated the standards for SuperFOIL! We cannot speak for other Multifoil manufacturers in the industry, but from a broad overview, quality Multifoil products from any manufacturer should be easily capable of achieving the thermal performance requirements.

Multifoil is just innovative in how it protects against heat loss and has been tested to the current standards. So, with the question of building regulations acceptance and quality standards for multifoil insulation put to rest, let’s give you clarity on where the old controversy on Multifoil even stemmed from and whether it’s even worth discussing anymore…

An Outdated Insulation Test Method

It all started around the mid-1990s when Multifoil was first introduced to the UK and finding great success used as a loft conversion insulation product.  During the time, a scientific dispute occurred over the most appropriate test method for measuring the thermal performance of multifoil insulation. Some popular thermo-reflective insulation manufacturers at the time considered ‘In-situ testing’ as the most appropriate test method to test multifoil insulation, in comparison to the ‘hot-box’ testing that more traditional insulation products underwent. And it was with this testing method that the unnecessary controversy around Multifoil began. 

The in-situ testing essentially assessed the performance of foil insulation directly within a building, rather than in a lab. This method measures how well the insulation works in real-world conditions; and the process includes installing the multifoil insulation in a specific area of the building and monitoring factors like temperature and heat flow over time. This helps determine the insulation’s actual effectiveness in reducing heat loss and maintaining indoor temperature, reflecting how it would perform in everyday use. 

In the following years old multifoil insulation manufacturers began testing multifoil products to adhere with the building regulations approved testing methods and were able to secure  performance certification provided by many reputable third-party testing organisations. But despite all this, the unfounded controversy remained, damaging trust in multifoil products which caused a shift toward using Multifoil as a supplementary insulation product, rather than the primary insulator for homes.

What’s Changed? 

Times have changed, and over the last two decades, significant developments have occurred in the field of thermal insulation technology, many of which have enhanced the accuracy of thermal insulation testing mechanisms and thermal properties of insulation materials. 

Recognising the cost, complexity, and time-consuming nature of the hot box testing method – many of the National, European, and International bodies decommissioned hot box testing for thermal insulation. They also recognised the ‘heat flow metre’ and ‘guarded hot plate’ tests as the new standardised test methods to analyse the heat transfer properties of insulation materials.

In particular, the guarded hot plate method is the absolute standard for thermal insulation testing at present in the UK (B.S. 874:1965), US (ASTM C 177‐63) and Germany (DIN 52612).

Heat Flow Metre

A heat flow metre test checks how well insulation materials resist the transfer of heat. Imagine two metal plates – one very hot and the other very cold – with insulation material wedged between them. With that set up, the test measures how much heat passes from the hot plate to the cold one through the insulation over a set amount of time. It does this by monitoring the temperature of the two plates and recording the amount of power needed to keep the temperature difference constant. This helps calculate how easily heat flows through the insulation material. Lower heat flow means the insulation is doing its job well, keeping buildings warm in winter and cool in summer.

Guarded Hot Plate Testing Method

The guarded hot plate test has a similar setup to the heat flow metre test, but  in the guarded hot plate test, we add something called a guard ring around the hot plate. This guard ring helps reduce heat loss at the edges of the plate, making the test more accurate. From there, we measure how much heat passes through the insulation – just like the other test – and calculate its thermal conductivity (the speed that heat conducts through) letting us know how well the insulation works.

When Would Multifoil Insulation Not Be At Its Best?

SuperFOIL Multifoil products are tested and certified by reputed third-party organisations to the correct standards, adhering to strict quality control guidelines; all of which means you absolutely can trust Multifoil to help you achieve your energy efficiency targets, insulation goals, and building control approval. However, Multifoil can only provide these benefits if it is properly installed, which is why we’ve put together this list of things you should avoid at all costs to protect yourself from being a victim of bad insulation.

1. Incorrect product: One of the biggest benefits of Multifoil is its versatility. There is a Multifoil product to address practically any insulation need. But that variety comes with a risk of its own; the risk of choosing the wrong product for the job! For example, Bubble wrap insulation products manufactured for garden rooms, garage doors, or sheds might not be the best choice to insulate your house’s roof, wall or floor. Identifying what product suits your project best should be a high priority matter, if you are looking to achieve great results. Which is why the technical support team at SuperFOIL makes it a point to respond to customers looking to choose the right product for the job within 8 working hours.

2. Incorrect thickness: Multifoil products are available in many different thicknesses that can achieve different levels of thermal performance. Therefore you need to ensure that you either choose a product that’s of the recommended thickness or choose a hybrid insulation system (installing two types of Multifoil products or combination of multifoil and traditional insulation).

3. Incorrect Installation: Flawed installation can not only limit the efficiency of any insulation product but could also lead to serious complications and even damage to the property. Some of the common mistakes people make while installing insulation are:

* Using the wrong product

* Using the wrong tools

* Incorrect battens

* Not counter battening

* Not leaving the recommended air gap

* Not joining or sealing corners/joints, etc., with tape

* Not following a continuous installation system

* Not removing the remains of old/previous insulation

* Neglecting any specific manufacturer’s recommendations

If you’re concerned about installing your Multifoil product properly, then we’d always recommend relying on the skills of a professionally trained installer!

How can you ensure your Insulation will achieve thermal requirements and building control approval?

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