| What is Roofshield |
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A triple layer spun bonded polypropylene breather membrane designed for use as an underlay on pitched roofs and for buildings with high internal temperatures and humidities. Roofshield provides temporary weather protection during the construction phase with full rainwater hold out.
BBA Certificate No. 96/3220 (warm roof) BBA Certificate 99/3648 (cold roof)
This unique central layer provides a fibrous structure which allows for a much higher breathability than other laminates which may include films. These small fibres give increased water hold out over spunbond single layer products and afford a number of advantages which are listed below.
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Resistance to water vapour ‘the lower the better’ |
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Air Permeability |
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Waterproof when fully supported - ‘some breather membranes can leak' |
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‘Ventilation to the underside of underlay not required in warm or cold roof applications’ |
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Drumming noise under wind action- ‘use a flexible sheet’ |
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Not affected by Timber Treatments |
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| Cold Roof Design (Non Ventilated) |
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The A. Proctor Group, over the past two years has carried out extensive research into the use of Daltex Roofshield breather membrane as the underlay in cold roofs without ventilation
The relative humidity and temperature throughout the construction, inside and outside the loft space, has been taken and moisture contents taken throughout the year to ensure that the timbers’ moisture content did not increase.
The summary of this research concluded that the moisture contents found in this roof were comparable with the moisture contents found in a conventionally ventilated roofspace
This unventilated Cold Roof design offers a number of benefits:
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No Requirements for Eaves, Ridge or Tile Ventilation of loft space |
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No Additional Risk of Condensation |
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Independent Research |
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Full BBA Certification |
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Increased Energy Efficiency |
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Easy to Install (laid the same as a traditional underlay) |
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| Functions |
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The underlay must perform four functions: |
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1 |
Secondary drainage layer
Wind blown rain and snow which finds its way below tiles and slates, or through side laps in metal sheets, drips onto the continuous underlay and drains safely down into the gutter and out of the building. Roofshield performs this function. |
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2 |
Temporary waterproofing
During construction, and in the event of future damage of slates or tiles, the underlay protects the insulation and building fabric below. Roofshield performs this function. |
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3 |
Condensation control
Warm moist air which rises up from within the building and into the roof construction, can pass freely through the breathing underlay. If condensation forms on the underside of the primary covering, then the drops of water falling onto the underlay would run down into the gutter. Roofshield performs this function |
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Wind
The roofing underlay should provide a barrier to minimise the wind load generated and the wind gusts acting on the slates and tiles and prevent wind driven snow or dust entering the roofspace. |
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| Product |
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Roofshield is a spun bonded polypropylene fabric manufactured in the UK and used as a breathing underlay for pitched roofs. It meets the following basic criteria:
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General
Roofshield is satisfactory for use as a fully supported or unsupported underlay in tiled and slated pitched roofs, constructed in accordance to the relevant clauses of BS 5534: Part 1: 1990. |
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Strength
Roofshield will resist the loads associated with the installation of the roof. Roofshield has adequate resistance to uplift forces likely to be experienced in most locations in the British Isles and for design purposes, may be considered equal or greater in strength to a Type 1F reinforced bitumen underlay as defined in BS 747: 2000. Tests on Roofshield fixed over rafters at 600mm centres with batten centres at 350mm have shown that the material does not extend unduly or tear around nail holes when subjected to a range of negative pressures. |
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Fire
Tested to DIN 4102 Roofshield achieves a B2 fire classification and will shrink away from the fire source. When the product is used unsupported, there is a risk that fire can spread if the material is accidentally ignited during maintenance works, eg by a roofer’s or plumber’s torch. As with all types of sarking material, care should be taken during building and maintenance to avoid the material becoming ignited. |
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Certification
Warm roofs has a current British Board of Agrément Certificate No. 96/3220
Cold roofs has a current British Board of Agrément Certificate No. 99/3648
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| Specification |
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| Physical Properties |
Test Method |
Result |
| Nominal Weight |
175 g/m 2 |
| Nominal Thickness |
0.6 mm |
Tensile Strength : 56 days aged @ 60 o C
along the roll
across the roll |
6.37 kN/m
4.60 kN/m |
Nail Tear Resistance
along the roll
across the roll |
156N
131N |
| Burst Strength, wet/dry |
488 kN/m 2 |
| Water Vapour Resistance |
0.09 MNs/g |
| Moisture Vapour Permeability |
2409 g/m 2 /day |
| Resistance to Water Penetration (Eosin Test) |
Pass |
| Air Permeability |
70 l/m 2 /s |
| Fire Resistance to Spread of Flame |
B2 |
| Head of Water |
1135 mm |
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| Roll Specification |
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| Roll Length |
50m |
| Roll Width (Other sizes available on request) |
1 m |
| Weight (1m x 50m roll) |
8.75kg |
| Colour |
Green Top (printed Don & Low Roofshield by the A Proctor Group) and white bottom. |
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