Fibre cement sheet Roofing : technical description

Steadmans are distributors of AS3, AS6 and Farmscape profiles from Marley Eternit, the Country's largest manufacturer of fibre cement products and the producers of profiled sheeting for over 90 years. The products are differentiated by the size of corrugation in the sheets; the AS3 profile having smaller corrugations than the AS6 and Farmscape profiles.

All the sheets are manufactured from a selected blend of Portland cement and water. This is reinforced with a mixture of both natural and synthetic fibres. The longevity of this formulation has enabled Marley Eternit to offer a 30 year guarantee on our sheets and fittings (available on request).

Marley Eternit have always worked to improve safety when using our range of roofing and cladding products. Building upon over 90 years experience in the UK roofing industry we have developed a purpose designed, reinforced fibre cement sheet - AS6 - that meets the high standards of safety in roofing work set out in the Health and Safety Executive document ‘Health and Safety in Roof Work’ (HSG 33). In addition to the AS6 sheet, we are proud to be able to offer a complementary range of accessories that meet the same high standards of safety.

Which profile?
The decision to use AS3, AS6 or Farmscape sheets will depend largely upon the following four criteria:

1. The scale of the building in question.
2. Compatibility with any existing materials.
3. The distance from centre to centre of the horizontal fixing rails or purlins.
   
4. Whether or not the roofing material is to be classified as non-fragile.

Reference should therefore be made to the sheet sizes, fixing details and product data provided before deciding which type of profiled sheeting to use.

AS3 The lower profile of this product makes it particularly suitable for a range of domestic, agricultural and light industrial buildings. It can be laid to a minimum roof pitch of 10°.

AS6 AS6 is a high strength fibre cement sheet with polypropylene reinforcement strips inserted along precisely engineered locations which run for the full length of the sheet in each corrugation. This provides maximum reinforcement strength with no loss of durability in service. AS6 can be laid to a minimum roof pitch of 5°. The cut-away illustration above shows the location of the polypropylene reinforcement strip inserted in a precisely engineered position in each corrugation of the AS6/Farmscape sheet.

Farmscape Farmscape uses the AS6 profile and is designed to reduce the visual impact of buildings on the landscape by giving them a more natural look from new. This effect is achieved by applying a surface pigmentation to the top face of the sheet. Unlike a dense layer of gloss paint, this pigmentation allows the distinctive texture of the fibre cement substrate to show through, and gives the product a far more natural appearance than the finish traditionally available to planners and designers. Farmscape can be laid to a minimum roof pitch of 5°. Table 03: Farmscape sheet sizes Length of sheet in mm 1525 2440 2900 Length of sheet in feet 5'0" 8'0" 9'6" Number of sheets per tonne 46 29 25 Area of sheet in sq. metres 1.66 2.65 3.15

Table 04: Manufacturing tolerances Length: +5mm / -10mm Cover width: +8mm / -2mm Overall width: +10mm / -5mm Thickness: +free / 0mm

Table 05: AS3, AS6 & Farmscape Sheet fixing details End lap: 150mm minimum Side lap: 70mm Purlins centres 1375mm maximum Clear span: 1300mm maximum Rail centres: 1825mm maximum Span between rails 1750mm maximum Unsupported overhang 400mm maximum

Colours Natural Grey Blue Gunmetal Grey Laural Grey Brown Anthracite Serpentine Bracken The colours shown here are unique to the fibre cement sheet roofing range. The colours have been chosen for their ability to harmonise with the most commonly used building materials and their ability to meet the majority of design requirements in both rural and urban areas. AS3 and AS6 are available in Natural Grey, Blue, Gunmetal Grey, Laurel Green and Brown. Farmscape is available in 3 matt colours - Anthracite, Serpentine and Bracken.