Welcome to the Saint Gobain Insulation UK Blog

Here you will find the latest articles written by our team focusing on insulation solutions, product developments, and technical guidance.

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Latest articles written by our team

A masonry cavity wall showing ISOVER CWS Glass Mineral Wool used to fully fill the cavity, or Celotex CW4000 PIR to partially fill the cavity. This building detail is for illustration purposes only and should not be relied upon.

Polyisocyanurate (PIR), glass mineral wool and blown insulation products may be specified as full and partial fill insulation solutions to improve the U-value of a masonry cavity wall. Choosing between full and partial fill installation and subsequently selecting the correct insulation type is essential in terms of compliance with Building Regulations and is crucial to the energy performance and the carbon footprint of a building. There is a variety of products available for full fill cavity insulation. PIR, glass mineral wool and blown insulation offer different properties and specification will depend on the client’s needs and building performance requirements. Full fill solutions are designed to prevent moisture movement through the cavity, eliminating the need for a clear cavity that is required when partial fill insulation products are installed. The distinctions between cavity insulation products available on the market are often subtle, but it is crucial that the right products for a project are selected to achieve optimum performance of the cavity wall insulation. All cavity wall solutions must have third-party certification, confirming they are fit for purpose. These solutions must also be specified and installed in accordance with the relevant certifications. We will now explore the benefits of each cavity insulation type in the context of full and partial fill installation.

PIR  Glass mineral woolBlown Insulation
Full fill
Partial fillXX
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Masonry cavity wall constructions can be filled with a rigid full fill polyisocyanurate (PIR) insulation product, or a flexible glass mineral wool solution. In both cases, the selected product should carry third-party certification confirming its suitability for use in cavity wall applications.

How does a rigid full fill solution differ from a partial fill solution?

Full fill glass mineral wool batts, such as ISOVER Cavity Wall Slab, are the traditional full fill cavity wall insulation solution. By contrast, rigid insulation boards for masonry cavity walls have typically been associated with partial fill applications only.

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How does rigid full fill cavity wall insulation work?

Traditionally, rigid insulation boards used in masonry cavity wall applications were offered only as a partial fill solution. Now, rigid full fill solutions for masonry cavity walls mean the clear air cavity can be significantly reduced or eliminated entirely.

By filling more of the wall cavity with thermally efficient polyisocyanurate (PIR) insulation, masonry cavity walls can achieve lower U-values with little or no increase in the overall thickness of the wall construction.

Using rigid full fill PIR cavity wall insulation to lower U-values

With a thermal conductivity as low as 0.021 W/m.K, a full fill PIR solution offers a more efficient way to insulate a cavity compared to partial fill solutions. It is also more thermally efficient than a corresponding full fill glass mineral wool product, making it ideal for projects that require both lower U-values and minimum wall thicknesses.

Masonry cavity walls featuring rigid full fill insulation products should be designed in accordance with the manufacturer’s details. For example, Thermaclass Cavity Wall 21 can be installed with a nominal 10mm cavity (which benefits from the low emissivity facing of the insulation board), or as a true full fill solution.

Using rigid full fill PIR cavity wall insulation to protect against moisture ingress

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Helping contractors make the most of the Green Homes Grant

With the launch of the Green Homes Grant, the government has demonstrated its belief that improvements to people’s homes will provide a lasting effect not only to the occupants of dwellings but also the economy. As Alok Sharma, the Business Energy Secretary, stated following the launch of the scheme in August 2020:

“Green Homes Grants are a key part of our plans to build back greener, helping make 600,000 homes more energy efficient with government vouchers, while supporting 100,000 skilled jobs and supporting our transition to net-zero carbon emissions by 2050.”

Several energy efficiency measures can be installed through the Green Homes Grant. These include loft insulation, internal wall insulation, external wall insulation and floor insulation, as well as double glazing and ground-source heat pumps.

As a contractor, it may be challenging to determine which measures to focus on and why. There are a number of considerations to weigh up, such as your technical proficiency, the number of jobs to cover, what’s best for the customer, the ability to source materials and, perhaps the most important of all, the ability to sell this vision and your services to the customer.

The benefits of loft insulation

These days, people care a lot about the environment and their carbon footprint. One of the largest contributors to our carbon emissions is the energy used in heating buildings. A large reduction in the heat loss of a house not only means an equivalent reduction in energy bills but also the same decrease in the contribution to climate change. Cutting the UK’s carbon emissions is also a priority for the UK government, and one of the main reasons for implementing the Green Homes Grant scheme.

Loft insulation, in particular, offers a huge range of benefits for homeowners, insulation installers and the environment.

According to the Simple Energy Advice (SEA) website, which is the entrance hub for the Green Homes Grant, the average amount of heat lost through a loft is around 25%. So, loft insulation is an obvious way to reduce heat loss and energy bills.

In addition, correctly installed loft insulation can last over 40 years. The cost of installing loft insulation is usually around £400, and this can generate an annual energy saving of over £200. By doing the maths, it’s easy to see the long-term benefit of this simple energy-efficiency measure. What’s more, its quick installation means that contractors can complete more projects in less time.

Improving energy efficiency with loft insulation

In many homes, a product from ISOVER’s Spacesaver range is likely to be the ideal loft insulation. This is a glass mineral wool that comes in various thicknesses and as such will cover the variety of jobs you work on.

You may also want to consider the advantages of Celotex PIR boards. Two products from the Celotex 4000 range are suitable for use in the loft space: Celotex GA4000 or Celotex XR4000. These can provide the same insulating benefit as glass mineral wool, but with a thinner build-up. This can be especially useful if the occupant wishes to use the loft for storage and wants to retain head height. PIR boards are structural and can be laid across the joists as opposed to adding additional joists and then floorboarding.

Choosing between mineral wool and PIR loft insulation

The real difference in choosing between glass mineral wool and PIR insulating material will come down to a variety of the factors that will be specific to each project. Customer requirements and your preferences as the contractor may also need to be considered – particularly in terms of material handling and being able to get products to site and into the installation location.

Topping up existing loft insulation

Homes with existing loft insulation may require a top-up of, either because the old insulation has settled and lost thickness over the years, or because it was never installed at today’s recommended thickness.

It is relatively easy to see if a project is suitable for a top-up, and top-ups are covered by the funding if the existing insulation doesn’t meet current Building Regulations. Depending on the requirements, any of the ISOVER or Celotex products listed above can be used to top-up existing insulation.

Becoming a Green Homes Grant installer

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This post aims to cover what a vapour control layer is, why it’s important and when it’s applicable to roof and floor applications.

Today, we are talking about another vital construction component called a vapour control layer, or a VCL.

At Saint-Gobain Insulation UK and within our bustling Technical Support Centre, our advisors are regularly asked questions relating to the VCL. What is it? What does it do? Am I using it the right way? With this in mind, our technical advisors have put together a VCL focussed FAQ post.

What is a vapour control layer (VCL)?

A vapour control layer helps you protect your building from the consequences of condensation. Condensation is formed when warm moist air penetrates the building fabric and then condenses into a liquid on contact with the colder surfaces outside the insulation layer. The idea behind a vapour control layer is to install it on the room (i.e. warm) side of the insulation so it blocks the passage of warm moist air entering the structure.

Why is a VCL important?

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What is PAS 2030 and how does it apply to the Green Homes Grant?

Publicly Available Specification (PAS) 2030:2017 describes how energy efficiency measures in dwellings should be specified, installed and commissioned. It forms part of a network of standards and quality assurance measures intended to deliver high quality retrofit work.

The Green Homes Grant scheme requires that installers are certified to PAS 2030 to ensure the delivery of high quality of work throughout the industry. However, the scheme was launched at a time when the retrofit sector was moving from PAS 2030:2017 to PAS 2030:2019. A temporary transition policy has been announced by BEIS (the Department for Business, Energy and Industrial Strategy).

Essentially, Green Homes Grant work may be carried out under either Specification, apart from in certain defined instances where both PAS 2035 and PAS 2030:2019 must be used.

How does TrustMark registration fit with PAS 2030?

The Green Homes Grant scheme has created a surge of interest in domestic retrofit. To minimise the risks of poor quality work being carried out, the government has sought to incorporate quality management into the scheme and as such all businesses must be registered with TrustMark which requires a commitment to customer service, technical competence and trading practices.

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The government has launched its new £2bn Green Homes Grant scheme. Through the scheme, eligible homeowners will be able to apply to help pay for the installation of energy efficiency measures such as thermal insulation, as well as new boilers, double glazing, draught-proofing and solutions such as air-source and ground-source heat pumps.

What is the Green Homes Grant?

The Green Homes Grant is part of a broader £3bn investment plan to cut greenhouse gas emissions across the country. It will help homeowners pay for home improvements that will boost energy efficiency whilst reducing energy bills and contributing to the UK’s target of net-zero emissions by 2050.

Up to 600,000 eligible homeowners will be able to apply for vouchers worth up to £5,000. These will cover up to two-thirds of the cost of the upgrades, with homeowners paying the balance. For some of the country’s lowest-income households, vouchers up to £10,000 may be available which could cover up to 100% of the cost up to the £10,000 voucher limit, with the remaining balance payable by the homeowner.

Depending on the home and the works carried out, it is estimated that the improvements could save households up to £600 a year in energy costs.

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The £2bn Green Homes Grant scheme is a government-funded voucher scheme that helps homeowners pay for the cost of installing thermal insulation and other energy-efficiency measures in their homes.

As part of a broader £3bn investment plan by the government, the scheme was launched to improve the energy efficiency of the UK’s housing stock, contributing towards the goal of net-zero emissions by 2050. Its launch, amid the economic downturn caused by the Covid-19 pandemic, is hoped to give a boost to the economy, particularly the construction sector.

For contractors, the Green Homes Grant could be a welcome source of new work – but you’ll have to act quickly to ensure you are approved to carry out installations under the scheme.

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