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Roofshield


 

Roofshield is a unique, three - layer, nonwoven, spunbonded, polypropylene breather membrane with a patented melt - blown core. It is intended for use as a pitched roof underlay (breathable roofing felt) and is fixed beneath tiles and slates.

Roofshield provides a secondary barrier to the ingress of rain, wind and snow. It has a low vapour resistance and is air - permeable; additionally, it eliminates the incidence of interstitial condensation in pitched roofs.

The product provides the most cost - effective solution to controlling interstitial condensation in a pitched roof.

  • Water Resistant
  • Low Vapour Resistance
  • Air Permeable
  • No vapour control layer required
  • UV Resistant
  • Hydrophobically treated
  • Supplied in 1m x 50m rolls
  • Eliminates low & high level ventilation

  Roofshield Roll - 1m x 50m

Literature Download

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BBA Certification

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NBS Plus & BIM

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CAD Details

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UK Availability

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Worldwide Availability

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  Roofshield - Covering All The Bases

As an effective method of addressing condensation in roofs that needs no ventilation or tapes, the Roofshield air and vapour permeable membrane from the A.Proctor Group presents a compelling case.

Vapour permeable membranes have been gaining favour in recent years for preventing condensation in cold pitched roof applications, providing a combination of water resistance and a high degree of breathability, alleviating the need for traditional eaves and ridge ventilation. This ability of the A. Proctor Group’s vapour permeable membrane product Roofshield was recognised by the NHBC in 2011 following an amendment to their Technical Standards resulting from complaints of condensation occurring in some non-ventilated roofs. This change required ridge ventilation to be installed in all cold roof constructions where a vapour permeable underlay was used. The Partners in Innovation (PiI) study, carried out in 2004, showed that a vapour and air permeable underlay, Roofshield, could be used to prevent condensation without the need for additional ventilation.

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As an effective method of addressing condensation in roofs that needs no ventilation or tapes, the Roofshield air and vapour permeable membrane from the A.Proctor Group presents a compelling case.

Vapour permeable membranes have been gaining favour in recent years for preventing condensation in cold pitched roof applications, providing a combination of water resistance and a high degree of breathability, alleviating the need for traditional eaves and ridge ventilation. This ability of the A. Proctor Group’s vapour permeable membrane product Roofshield was recognised by the NHBC in 2011 following an amendment to their Technical Standards resulting from complaints of condensation occurring in some non-ventilated roofs. This change required ridge ventilation to be installed in all cold roof constructions where a vapour permeable underlay was used. The Partners in Innovation (PiI) study, carried out in 2004, showed that a vapour and air permeable underlay, Roofshield, could be used to prevent condensation without the need for additional ventilation.

The potential cost savings on a construction project of being able to install an effective membrane without the need for ventilation, despite the high quality nature of the Roofshield membrane itself, have been shown in a 2014 report undertaken by property consultants Hardies. More recently, the the case for Roofshield has been further bolstered with amendments to official guidance on roof construction due to its ability to resist wind uplift without requiring tape, as is detailed below.

Background

Roofshield was developed 20 years ago in response to problems caused by the double-whammy of the UK’s fondness for cold pitched roof construction, and increasing thermal performance requirements which led to a tendency to place additional insulation above the ceiling joists leading to an increased risk of condensation in the roof space. With vapour condensing on the cold surfaces in the roof, particularly in winter months, a variety of efforts were made across the industry to develop membranes which would allow the vapour to escape. These breathable membranes were designed to be installed over the rafters as the roof underlay as an alternative to traditional 1F felt.

The majority of those membranes were vapour permeable but air tight, rather like a Gore-Tex jacket. While water resistant, offering additional benefits during construction similarly to Roofshield, they did not completely prevent condensation within the roof space, meaning some low and/or high level ventilation had to be introduced in order to allow air to circulate and fix this problem.

Therefore two types of technological solutions have been presented to specifiers; vapour permeable but air tight solutions, based on film laminated polypropylene technology which has been favoured by several manufacturers, or the vapour and air permeable version alleviating the need for ventilation, such as Roofshield. A debate continues to run in the industry around whether roofs fitted with the air tight membranes will still require ventilating due to their being vapour permeable, although testing undertaken within the 2004 Partners in Innovation study confirmed this was the case. The continued discussion has however led to a recommendation for a vapour control layer to be considered at ceiling level to reduce the moisture load into the roof space when film based laminates are used as the underlay.

Iain Fairnington, Technical Director of the A. Proctor Group, explains the building physics around why air tight membranes’ limited vapour permeability means that condensation can still occur: “If you have a big cold roof space, and you have a sudden drop in temperature, you want to have air movement. People assumed that because they were installing a vapour permeable membrane you didn’t need to ventilate your roof, but in certain circumstances moisture levels were too high or temperatures too cold to allow the vapour to permeate without condensing.”

By contrast, Roofshield has a far higher degree of vapour permeability, as well as air permeability, so will still perform in conditions in which air tight alternatives will not. The 2004 study was conducted on a cross-industry basis with Glasgow Caledonian University because there was a view that a consensus was desirable on whether it was necessary to ventilate buildings using vapour permeable membranes. It had the result of “dispelling a lot of theories around ventilation” says Iain Fairnington.

In fact the study contained the crucial finding that when a roof was unventilated, and used an air and vapour permeable underlay, such as Roofshield, this would further reduce and inhibit the formation of condensation on the underlay. This contributed to the NHBC making a statement in their Technical Extra bulletin Issue 6 that independently certified air and vapour permeable underlays, such as Roofshield, could be used without additional ridge ventilation in cold roofs. This has seen a groundswell of interest in the product recently, aided by its hydrophobic and UV resistant qualities. Another key benefit for installers is that the product is manufactured in lightweight 1 m wide rolls, the same size as traditional IF felt underlay, and can therefore be fixed and laid on open rafters in the same way, reducing health and safety risks of overreaching with wider membranes on open rafters.

Meeting the new Code of Practice on wind uplift

While there has been widespread acceptance of the abilities of air permeable membranes to offer a range of benefits for contractors and developers, the 2014 revision of BS 5534 Slating and tiling for pitched roofs and vertical cladding - Code of Practice caused a stir in the world of roof construction and again put the spotlight on their differences. This was particularly with regard to the technical specification of underlays, in particular lightweight membranes, and how they behave under wind.

The revision of the standard includes a number of recommendations which affect the way all slated and tiled roofs will be constructed in future. Advice contained in Annex A has been introduced to avoid incorrect specification which has been perceived, in extreme cases, to potentially lead to underlays being lifted by wind, ballooning and dislodging slates or tiles. The annex includes a new wind uplift resistance test and classification system for underlays in relation to the batten gauge being used and the location of the particular project. It requires manufacturers to provide a Zonal Classification label to enable specifiers to easily identify a suitable underlay.

The change has led to some membranes manufacturers introducing tapes, or integral adhesive strips, which will enable them to be used, sealed at the overlaps. However as Iain Fairnington, who sat on the standards committee, explains, this was not an requirement for Roofshield being a heavier membrane, a factor which has been welcomed by installers: “I was told by the roofing industry that they do not want tapes, they may work well in a lab, but out on site, the situation with wind, dirt and dust does not lend itself to tapes.”

The A. Proctor Group has undertaken independent, third party testing, in accordance with Annex A, to establish that Roofshield is fully compliant and are providing specifications to interested parties on that basis. This enables Roofshield to be used in three of the five specified zones with no additional requirements such as time-intensive taping, and in all zones if an 11mm counter batten or 38mm tiling batten is used.

This new requirement for compliance with wind uplift issues brings the conclusions of the Partners in Innovation research back into the foreground again, as the findings were based on roofs with open overlaps (ie not taped). In that study, even in the case of air tight membranes there was a degree of vapour escape. Now however, if laps must be taped, that mechanism for escape has gone. Iain concludes: “While there does not seem to be much appetite to confront this issue, there is a very real risk that we will see moisture occurring again in such specifications.”

The recent Code of Practice revision, plus the previous statements from the NHBC and the PiI Research, adds up to a compelling case for air and vapour permeable membranes as a robust and installer-friendly solution for healthier buildings. In the case of Roofshield the manufacturer is able to make a credible case that the product will comply with all standards and avoid the need for additional measures such as ventilation and tapes. Before the PiI study and research into implications of omitting ventilation, there had been a lot of resistance to change in the industry; however specifiers now have more and more reasons to believe that Roofshield offers the simple answers.

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Contact Us

  8:30am - 5pm, Mon - Fri

  01250 872 261

  01250 872 727

  

  A. Proctor Group Ltd., The Haugh, Blairgowrie, PH10 7ER

 

Testimonials

"As a roofing contractor specialising in the larger, more prestigious, type of project, we prefer to use only the highest quality products. Therefore we use Proctor Roofshield wherever possible; we have been using it for over 15 years, together with their condensation risk analyses and U-value calculations."

Mike Camilleri - Camilleri Roofing

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