FAQs - Frequently asked questions

How thick do I need to insulate?

We recommend that you seek advice from your architect, designer, energy assessor etc. to determine the appropriate insulation thickness. If you already know the desired performance, you can contact our Technical Services team for U-value calculations or look up the required R-value and corresponding thickness in the technical datasheet.

The cleanest energy for heating and cooling, is the energy you do not have to use. That is why we recommend to insulate a flat roof to a higher standard than the minimum requirement. We recommend a minimum of 45 mm Deck-VQ® (Lambda (λ) = 0,009 W/mK) for renovation and 60 mm (Lambda (λ) = 0,008 W/mK) for new build.

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How to install Deck-VQ® vacuum insulation panels?

Deck-VQ® can be applied in warm flat roofs or terraces of a new build and refurbishment projects. Generally speaking the panels are installed over the existing roof covering (refurbishment) or new vapour control layer (new build). The waterproofing system is then applied on top of the insulation and finished in an appropriate manner.


The Deck-VQ® concept is a complete package, designed to limit the risk of damaging the VIP inside during installation.

To take away your concerns, we have included a couple of features and services:

NO drilling allowed? How do I fix Deck-VQ®?

  • The PIR protection boards offer compatibility with a variety of adhesives and waterproofing systems*.
  • The high density PIR protects the VIP inside from normal physical damage, which allows a ballasted build-up.

NO sawing allowed? How do I cover the complete surface?

  • Deck-VQ® panels are available in four standard dimensions (mm x mm): 1200x600 / 1200x300 / 600x600 / 600x300 which make it possible to design an optimal configuration for your project.
  • Around details (e.g. corners, edges and roof penetrations) or to fill gaps, we provide PIR insulation in the corresponding thickness.
  • Our technical services can provide an optimized layout scheme (like a puzzle) as a guideline for the installation. Do not hesitate to contact us!

    Example of a layout scheme:

*We recommend cold adhered single-ply systems (e.g. fleece backed PVC or fleece backed EPDM) or multi-ply bituminous systems (self-adhesive partially bonded base sheet and torch-on cap sheet). For more information on compatibility or support for you project, please contact our technical services.


***UK ONLY: Liquid applied roofing is also possible. In this case, we provide a 3 mm bituminous layer on top.

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Is a vapour control layer (VCL) required in a floor insulation application?

In addition to the damp proof membrane (normally a 1200-gauge polythene sheet below the insulation), a 500-gauge polythene VCL should be laid over the insulation. Where a concrete slab or a screed is to be poured on top, the VCL will also protect the foil face of the board from alkalis within the concrete, and stop poured concrete opening board joints and causing a thermal break.

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Is Eurothane PL available with a vapour control layer?

Recticel Insulation's Eurothane® PL is a versatile product that can be fixed either mechanically or with gypsum adhesive, in accordance with installation guidelines. It has a built-in vapour control layer as standard, located between the PIR core and the plasterboard.

What air gap is required between insulation and breather membrane?

This should be confirmed in the membrane manufacturer's BBA certificate, though 25mm to 50mm is typical.

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What are the main tips for installing Recticel Insulation boards correctly?

  • Use the right board for the application - the right type and the right format.
  • Store the boards in a dry place above the ground, and use them when they are dry.
  • Handle boards carefully - do not throw or kick them, be careful not to damage them.
  • Ensure the intended substrate/base is clean, even, dry and smooth.
  • Apply an air screen, sealing layer or damp resistant layer if necessary, particularly in flat roofs.
  • Push boards together well.
  • Always keep boards dry during rain showers.
  • Always cover boards at the end of the working day.
  • Always follow installation instructions provided.
  • Always use the right attachment methods.
  • Measure and cut accurately to fit using a fine toothed saw or sharp knife
  • Ensure that any adhesive is compatible with the foam

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What if I cannot provide all of the information required for thermal calculations of a specific project?

It is possible for us to make certain assumptions when performing a calculation, but this can reduce the accuracy of the final result. Assumptions are routinely made about the types of fixings to be used, but we will always try to inform you if a general figure has been used where more accurate data could affect the calculation result.

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What insulation products can be used with underfloor heating?

Recticel Insulation's Eurothane® GP boards are compatible with both wet and electrical underfloor heating systems. Clipping a wet system through the VCL described above will not compromise the performance of the VCL or the insulation.

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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 the BBA Competent Person Scheme?

The scheme, of which Recticel Insulation is a member, is designed to ensure consistency and accuracy in the provision of U-value calculations through a process of assessment, certification and continuous monitoring. Not all insulation manufacturers are members of the scheme.

Further BBA Details

How can we help you?

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