Polycomp Products Limited

PART 1 - THE MATERIAL

Hunton Fiber Sarket is an 18mm bitumen impregnated fibreboard, developed in Norway from sustainable waste timber and designed for use as a combined sarking and breather membrane. The boards have a special high density bitumen impregnated layer on the top face providing a high degree of watertightness. However the boards simultaneously satisfying the water vapour permeability performance requirement of breathing roofs. The standard board size is 575mm x 2400mm as laid and weighs 7kg. The boards have a tongue and groove on all four sides as shown below.

PART 2 - DESCRIPTION

Hunton Sarket provides effective wind protection, enhanced U-value performance, and reduction of condensation when used in roof applications.

PART 3 - ENVIRONMENT

Using environmentally friendly production methods, Hunton Sarket is made from 100% wood waste and the weather wood waste and the weather resistant skin is made from resistant skin is made from recycled newspaper.

PART 4 - PERFORMANCE

4.1 Strength

Sarket provides efficient permanent wind bracing in the plane of the roof for normal low rise applications. Care should be taken to only stand on supported battens during fixing as boards should not be walked on during or after installation.

4.2 Thermal Insulation

Insulated roofs using Sarket board can demonstrate U-value improvements of up to 7% compared with normal roofing felt products.

4.3 Watertightness

In use water vapour will penetrate into the tongued joints of the boards causing swelling of the board which enhances the natural water tightness of the roof. The board has demonstrated water tightness under pressures of between 0-500 N/m² however for long term durability boards should not be used where they may be continually exposed to water in the finished roof

4.4 Installation

Sarket should be installed when the boards are dry to provide a wind and water tight roof. The roof should have a minimum 17 degree roof pitch with ventilation between the tiles and the Sarket.

The final roof covering should be laid as soon as possible after installation to avoid extended exposure to the rain.

The boards should have their long sides perpendicular to the rafters with those rafters having a maximum spacing of 600mm. The male profile should point up the slope of the roof and final fixing should be with clout nails at 150mm at roof edges and 250 elsewhere.

For additional fixing details contact Polycomp.

4.5 Performance Characteristics

Thickness	18 mm
Sheet size	2420 x 595 mm
Cover size	2400 x 575 mm (1.38m)
Weight	4.8 kg/m2 (7kg /board)
Density	250-270 kg/mm2
Bending strength (length)	1.5 kN/mm2
Bending strength (width)	1.7 kN/mm2
Shear strength (100mm nail centres)	1.75 kN/m
Shear strength (150mm nail centres)	1.17 kN/m
Racking Strength*	1.78 kN/m
Water vapour resistance	1.82 MNs/g
Water Vapour Transmission Resistance (Wet cup method)	1.38 MNs/g
Thermal conductivity	0.05 W/mK
Watertightness	Tight at 1 kPa
Airtigthness (material)	0.012 m3 hPa
Airtightness (interlocked boards)	0.031 m3 hPa
*Racking strength tested in accordance with bS5268 section 6.1 using perimeter nail spacing of 75mm and intermediate spacing of 150mm