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Pir Pocket Guide
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FAQs

The following questions provide an outline of common queries regarding Recticel Insulation’s products. For further information, please see our product literature and detailed installation guides, or contact the Recticel technical services helpdesk.

Do joints between boards need to be sealed?

It is good practice to seal board joints as it controls the rate of passage of water vapour and improves the airtightness of the building envelope - an increasingly important element of the Building Regulations Approved Document L.

One common method is to use a self-adhesive aluminium foil tape. Depending on the proposed construction, taped board joints may act as a vapour control layer (VCL) on their own or be used in conjunction with a conventional sheet VCL like polythene.

Abutments with other construction elements should be sealed with a low modulus silicon sealant.

How can I get a U-value calculated for a construction using Recticel products?

Please contact our technical support team on freephone 0800 0854079 or see the U-value section here

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

Can electric cables be channelled into Recticel?

No, as this would reduce the performance of the boards.

Cables can penetrate the insulation with no detriment to the cable sheathing.

Any cables penetrating or lying against insulation should be oversized to cater for increased operating temperature. If in doubt, consult a qualified electrician.

What about a condensation risk analysis?

Our U-value calculation software also models condensation risk in accordance with BS 5250: 2011, and it forms part of the calculation as standard. We will always aim to provide appropriate technical advice if a proposed construction is showing a condensation risk. However, please bear in mind that the calculation service is not a design service - we can only work from the information provided to us.

What is the difference between a U-value and an R-value?

U-values take into account all elements of a construction, including thermal bridges. They can only be worked out by calculation. The R-value, or thermal resistance, is a measure of the insulation board on its own, dividing the thickness (in metres) by the thermal conductivity (lambda value, W/m.K). The R-value can be used to compare how different thicknesses of products with different lambda values perform comparatively.

Can I install downlighters in conjunction with Recticel Insulation?

The surface temperature of a lamp can reach 2000C. Without adequate ventilation to allow the escape of heat, downlighters can cause fires. Recticel recommends the following measures are taken when installing downlighters:

Downlighters should not be recessed into insulated ceilings if they penetrate the vapour control layer (VCL). This will result in them drawing warm moist air into the roof space where it could condense and drip back out of the fitting, causing a potential fire risk.

Where downlighters are to be used they should be fitted into a false ceiling below the structural ceiling.

Overheating can occur where thermal insulation is laid over existing downlighters and any associated transformers that are not designed to operate under these conditions. Cables and other electrical equipment should not be covered by insulation.

In all cases, the downlighter manufacturer's instructions should be followed. They should specify the amount of space to be left around the back of the fitting, its fire rating, whether it can be covered with insulation, and the type/wattage of suitable lamps.

If in doubt, consult a qualified electrician.

Can insulation be placed between and over flat roof joists?

BS 5250:2011, the British Standard for the control of condensation in buildings, does not recommend installing insulation between timber joists as well as above the deck.

What fixings should I use when installing Eurothane GP over the rafters of my warm roof?

To ensure the appropriate resistance to wind loadings, we generally recommend the use of helical fixings. Manufacturers provide a calculation service to work out the size and number of fixings required in your roof, and aid compliance with British Standards and Euro-codes.

Counter battens fixed over this insulation layer should be appropriately sized to accept the helical nails being driven through to the rafters below. 25mm wide battens are likely to split, so a minimum of 38mm x 25mm should be used. 50mm x 38mm battens would be a further improvement

Can a breather membrane be laid directly over your insulation boards?

Different breather membrane manufacturers have different guidelines for their products, and these should always be consulted prior to installation. It may be possible to lay the breather membrane on the insulation, but with a counter batten airspace above.

How are Eurothane PL boards fixed?

Eurothane PL is a versatile product that can be fixed either mechanically or with gypsum adhesive, in accordance with our installation guidelines.

What is the minimum required clear cavity?

Eurowall Cavity is certified for use in conjunction with a 25mm cavity. However, some warranty providers will not accept this and require a 50mm cavity, as do Scottish Building Standards. A wider cavity should be used in exposed locations.

If in doubt, seek advice from your Building Control Officer.

Can Eurothane GP be installed exposed to the ground? Is a vapour control layer (VCL) required in a floor?

In addition to the DPM (normally a 1200-gauge polythene sheet), a 500-gauge polythene VCL should be laid over the insulation if a concrete slab or a screed is to be poured on top.

This will protect the foil face of the board from alkaline within the concrete and provide a barrier to stop water contained in the slab/screed from penetrating the board joints. It also stops the board joints being opened by poured concrete and causing a thermal break.

If a floating timber floor is to be laid, the VCL should be installed below the floor finish.

Can I use Eurothane GP to insulate my loft ceiling?

Yes, our boards can be used both between and over ceiling joists in either new-build or refurbishment scenarios, and where the loft space is well ventilated. Eurothane GP can be used over the joists ready for boarding out - the compressive strength of the product is acceptable for a loft intended for storage and occasional access.

What quality standards do Recticel products meet?

Recticel Insulation prides itself on the quality of its product, particularly its dimensional stability and flatness. We consider the quality of our boards to be second to none.

Recticel operates a Quality Management System in accordance with the requirements of BS EN ISO 9001:2008 and offers CE Marking to 'ISO EN 13165 - Thermal insulation products for buildings - Factory made rigid polyurethane foam (PU) products - Specification'.

Do Recticel insulation boards release harmful toxins when heated up?

No, our boards do not release any sort of gas or toxins - harmful or otherwise - when used in hot situations (e.g. lining a sauna). As long as the correct instructions/processes are followed when using and installing the boards, an indefinite and consistent service life and performance can be expected.

Does Recticel Insulation offer a full-fill cavity wall product?

We only produce a partial-fill board, which cannot be used as a full-fill solution.

Can Eurothane GP be used in a flat roof application?

Eurothane GP is best suited to cold roof constructions, fitted between timber joists with a 50mm ventilation space above. Other Recticel flat roofing boards have been designed for warm flat roofs, depending on the type of waterproofing membrane and fixing methods required.

For domestic or smaller projects with a warm roof, our Plylok board offers insulation with a 6mm ply bonded to it, suitable for applying a felt or GRP finish. This ply thickness has been selected to minimise condensation risks in this sort of build-up.

Are Recticel Insulation products suitable for use in inverted roofs?

No, they should be installed below the waterproofing membrane.

Where can I buy Recticel products?

Recticel Insulation's products are on sale via a network of dealers and merchants, including Jewson, Minster Insulation, Sheffield Insulation Group and others.

Do you offer a tapered insulation product?

Many flat roofing problems are attributed to ineffective rainwater run-off. This can cause deflection of the roof deck and 'ponding' of rainwater, and have a significant impact on the lifespan of the roof. Recticel's sister company, Gradient Insulation, provides bespoke tapered insulation solutions, allowing virtually any fall to be created on either a new or existing roof. A Gradient tapered roof will:

  • Improve thermal and acoustic performance
  • Minimise ponding and roof loading
  • Restrict build-up of rooftop debris
  • Reduce the resulting maintenance costs
  • Provide a longer, more effective working life
  • Aid compliance with Building Regulations

In providing this service, Gradient Insulation will work out a detailed roof plan and calculate the exact number of boards required in advance. They work exclusively with Recticel to provide specialist PIR insulation solutions, but are not limited in their choice of materials and can produce specifications that include mineral wool, polystyrene and cork. This enables Gradient to deliver truly unique and bespoke solutions, utilising the best characteristics of all the insulation materials available in the UK today.

For further information on tapered roofing schemes please go to www.gradientuk.com

What is the maximum temperature resistance of Recticel insulation products?

Recticel Insulation products can withstand a safe operating temperature range of -20°C to 100°C. Higher temperatures can be withstood for a brief time in certain applications, for example when adhering hot bitumen to appropriate flat roofing boards.

What products can be used with under floor heating?

Eurothane GP boards are compatible with both wet and electrical under floor heating systems. Clipping a wet system through the VCL described above will not compromise the performance of the VCL or the insulation

Are Recticel Insulation's products listed in the BRE Green Guide?

Recticel Insulation products manufactured in the UK have a summary rating of A, as per the 2008 Green Guide to Specification produced by the BRE. The detailed breakdown of that rating is available under element number 815320017.

How environmentally friendly is the production of Recticel PIR insulation boards?

All Recticel Insulation products use CFC and HCFC free materials in their manufacture, and as such have a global warming potential (GWP) of less than 5, and zero ozone depletion potential (ODP).

Recticel Insulation, Stoke-on-Trent (UK), has been approved by Lloyd's Register Quality Assurance to the ISO 14001:2004 Environmental Management System standard.

How is Recticel Insulation made?

A simple chemical reaction between two raw materials (polyol and isocyanate) which, in reaction with a blowing agent, expands to form polyisocyanurate (PIR) foam. The reaction is exothermic and the embodied energy arising from the manufacturing process is minimal.

The foam expands and bonds to facing materials of different properties, depending upon the intended application. As it cools, it becomes rigid and is cut to the required dimensions

Is Eurothane PL available with a vapour barrier?

Eurothane PL has a built-in vapour barrier as standard, located between the PIR-core and the plasterboard.

Where can I find Declarations of Performance (DoPs) to support CE Marking claims?

DoPs are a requirement of CE Marking. All products are required to have one, listing the essential characteristics and performance of the product as declared under the CE Marking standard. Recticel Insulation's DoPs can be found here.

Are Recticel Insulation's products environmentally friendly?

Our boards are an extremely efficient form of insulation and over the life of a building, will save far more energy in their use than required in their production, resulting in significant reductions in energy consumption and cost, as well as reduced CO2 emissions.

Is Recticel Insulation's PIR foam classed as a material of limited combustibility?

When tested in accordance with BS 476-7, it is classed as combustible and with a Class 1 surface spread of flame. Recticel Eurothane FP insulation offers a Class 0 fire rating that makes it suitable for use in soffit lining applications or external rainscreen applications in buildings up to 18m high. Recticel Insulation PIR is not suitable for use as cavity barriers where required by Building Regulations Approved Document B.

What if I cannot provide all of the information required for an individual construction?

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.

What is the minimum working temperature for installing your boards?

Recticel Insulation products should not be installed on site when the temperature is below 5°C. Below this, condensation may form.

What if I require thicker insulation than the maximum Eurothane PL board?

Eurothane GP boards can also be used to line a structure, but they can ONLY be used with mechanical fixings. When using them to line existing masonry, a temporary adhesive (such as external quality silicon mastic) may be used to attach the insulation boards to the wall and the plasterboard to the insulation. However, they should then be screwed through to the wall using a similar fixing arrangement to that for plasterboard only.

How effective are Recticel insulation boards in terms of flood resilience?

In a report issued jointly by DEFRA, DCLG and the Environment Agency - 'Improving the flood performance of new buildings' - rigid PIR foam performs the best when installed in cavity walls.

Recticel boards have minimal water uptake due to their closed cell structure. During immersion in water for 24 hours, water absorption is limited to around 2%. The closed cell structure means that even when wet, Recticel boards will maintain their integrity. Other common types of cavity insulation such as mineral wool batts and blown insulation can slump when wet and retain moisture for longer, slowing down the wall drying process.

Is Eurothane PL available with water-resistant plasterboard?

Eurothane PL is made only with standard plasterboard, and is therefore unsuitable for use in wet rooms.

Are calculations done the same way for all building elements?

Generally speaking, yes - all calculations are done by the 'combined method'. However, ground floors differ slightly from other building elements in the information that is required. If requesting a calculation for a ground floor, please ensure that you provide a floor area and length of the exposed perimeter (i.e. the length of new floor along outside-facing walls). This allows us to calculate a perimeter/area ratio, which is crucial in the floor calculation.

What is the BBA/TIMSA 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. Further details are available here.

Not all insulation manufacturers are members of the scheme.

Do joints between boards need to be sealed?

It is good practice to seal board joints as it controls the rate of passage of water vapour and improves the airtightness of the building envelope - an increasingly important element of the Building Regulations Approved Document L.

One common method is to use a self-adhesive aluminium foil tape. Depending on the proposed construction, taped board joints may act as a vapour control layer (VCL) on their own or be used in conjunction with a conventional sheet VCL like polythene.

Abutments with other construction elements should be sealed with a low modulus silicon sealant.

Can Eurothane GP be used in a flat roof application?

Eurothane GP is best suited to cold roof constructions, fitted between timber joists with a 50mm ventilation space above. Other Recticel flat roofing boards have been designed for warm flat roofs, depending on the type of waterproofing membrane and fixing methods required.

For domestic or smaller projects with a warm roof, our Plylok board offers insulation with a 6mm ply bonded to it, suitable for applying a felt or GRP finish. This ply thickness has been selected to minimise condensation risks in this sort of build-up.