FAQs - Frequently asked questions

Can I walk on Deck-VQ® vacuum insulation panels?

Yes, this is possible due to the protection layers in high density PIR and the compressive strength of 150 kPa (CS(10\Y)150). Deck-VQ® is suitable for application in flat roofs and terraces, subject to light foot traffic.

As for every type of insulation, we recommend to limit the foot traffic during installation to a minimum and apply the waterproofing as soon as possible after installation. It is best practice to only install the area you are able to insulate AND waterproof in one day.

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Can tapered insulation be used on an existing flat roof?

Yes. Tapered insulation can be designed for both new and existing roofs.

For refurbishment projects, the existing roof construction should be assessed before a tapered insulation scheme is designed. The survey and design should consider the existing roof dimensions, drainage points, falls, obstructions, roof condition and the proposed new roof build-up.

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Can you drill, nail or saw into a Vacuum Insulation Panel?

No, because these actions will lead to the loss of vacuum in the VIP and reduce the thermal performance by a factor of three*.

Our Deck-VQ® concept offers an optimum protection to prevent most damage on site. (see “What is the difference between Deck-VQ® and a Vacuum Insulation Panel?”).



Our technical services provide guidance and deliver a detailed design for your project.
Do not hesitate to contact us for further information.

*The thermal conductivity of the core material rises to ca. 0,020 W/mK under ambient pressure.

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How is a tapered insulation scheme designed?

A tapered insulation scheme is designed around the geometry and drainage requirements of the individual roof.

The design process should consider factors such as:

  • Roof dimensions and geometry
  • Drainage outlets and gutters
  • Existing falls and backfalls
  • Rooflights and other obstructions
  • Required insulation performance
  • The structural deck
  • Waterproofing system
  • Required roof build-up
  • Upstands and perimeter details

Gradient provides a design service that produces a pre-designed, dimensionally accurate tapered insulation solution with detailed layout drawings.

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How is polyurethane ecological?

We do everything we can to reduce CO emissions2, but the core of our insulation products is also truly made of environmentally friendly materials.


Eco-friendly synthetic materials may seem strange to you, but with PU insulation, you will save 400 times more energy than they require for their production in 75 years. In short, a good thing for nature.

Sustainable development takes on its full meaning with Recticel Insulation polyurethane insulation:
not only does polyurethane insulation have a very high thermal performance that does not deteriorate over time, but Recticel Insulation polyurethane insulation also significantly reduces the carbon footprint of the insulation.

The proof by four:

1 - The least energy-intensive of all factory-made insulation is polyurethane insulation.

2 – Thinner and more efficient: With the same thermal performance, Recticel Insulation panels are up to 2 times thinner and 5 times lighter.
This reduces the quantities produced and so does the energy required.®

3 – Less bulky for better efficiency: This means fewer trucks to transport them.

4 – Less heavy: CO emissions2 are considerably reduced.

The ecological impact is controlled at all levels and the environment is better preserved.

We need to consume less energy:


Fossil resources such as oil are practically exhausted.
That is why we are advocating for the rational use of this oil.
In concrete terms: we need to burn less oil and use it to produce PU, the high-performance material of which our insulation materials are made.


Today, 96% of oil is used in the form of fuels.
The remaining 4% is processed into synthetic materials, of which only 0.08% is PU.
This is very unfortunate when you know that PU insulation saves 400 times more energy than it requires for its production.

The RECTICEL group acts at the international level, in all its businesses, for the protection of the environment.

What does “circularity” mean for Gradient’s products and processes?

Circularity means designing products and systems that minimize waste and keep materials in use for as long as possible. At Gradient, this includes responsible sourcing, efficient manufacturing, waste reduction, and developing pathways for recycling or repurposing materials at the end of their life cycle, all aligned with Recticel’s circular economy ambitions.

What does PEFC certification mean for Gradient and the Recticel Group?

PEFC certification ensures that the wood‑based materials we use come from sustainably managed forests. For Gradient, this means our sourcing practices align with strict environmental, social, and ethical standards reinforcing the Recticel Group’s commitment to responsible supply chains and traceable, sustainable raw materials.

What happens if a vacuum insulation panel is damaged?

Damage that penetrates the vacuum insulation panel can cause the vacuum to be lost, reducing its thermal performance.

For this reason, vacuum insulation panels should not be drilled, nailed or sawn.

Gradient specifically states that drilling, nailing or sawing a Vacuum Insulation Panel can cause loss of vacuum and reduce thermal performance. Deck-VQ® incorporates protective high-density PIR layers designed to provide additional protection to the vacuum panel during installation and use.

Installers should follow the manufacturer's installation instructions and avoid activities that could damage the panels.

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What is a Vacuum Insulation Panel or VIP?

VIP is the abbreviation of Vacuum Insulation Panel. A Vacuum Insulation Panel generally comprises a microporous core material (e.g. based on fumed silica), which is introduced into a high barrier multilayer foil envelope. The envelope is then evacuated and sealed, obtaining a near vacuum inside the envelope.

Because of the microporous core and the absence of air, excellent thermal properties are obtained. For our Vacuum Insulation Panel as such (Core-VQ®) we can declare a lambda value of 0,006 W/mK, which is typically 3-5 better than traditional insulation materials.

Vacuum Insulation Panels have already been used for several decades in high demanding applications, especially when stringent requirements for thermal insulation are set (e.g. refrigerators). As the thermal insulation of buildings has become increasingly important over the last years, Vacuum Insulation Panels have been introduced in buildings to meet the high standards.

Recticel Insulation offers the following products:

  • Core-VQ®: the ‘naked’ VIP and the heart of our vacuum insulation solutions that can be incorporated in a variety of systems (e.g. VIP inside Deck-VQ®)

  • Deck-VQ®: a premium solution, developed for flat roofs and terraces, where the VIP is protected by a high density PIR on all sides.

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What is a warm flat roof construction?

A warm flat roof is a roof construction where the insulation is positioned above the structural roof deck, keeping the deck and structure on the warm side of the insulation.

A typical warm roof build-up may include the structural deck, vapour control layer, insulation and waterproofing system. The exact arrangement depends on the roof construction and waterproofing system being used. Warm roof construction can provide continuous insulation across the roof, helping to reduce heat loss and improve the thermal performance of the building. The complete roof build-up should be designed to meet the required thermal, moisture, structural and fire performance criteria.

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