|Standard lengths (mm):
||1525, 1675, 1825, 1975, 2125, 2275, 2440, 2600, 2750, 2900, 3050
|Farmscape lengths (mm):
||1525, 2440, 2900
|Approximate covering capacities for estimated purposes:
|1375mm purlin spacing, normal side lap, 150mm end lap:
||approx. 1.13m² of material covers 1.0m²
|1375mm purlin spacing, normal side lap, 300mm end lap:
||approx. 1.19m² of material covers 1.0m²
The test for fragility of roofing assemblies’ ACR (M) 001: 2005 consists of a 45kg bag being dropped from a height of 1200mm onto a fixed sample of roofing. It is intended to provide information about whether the roof can support the instantaneous loads imposed on it by persons stumbling or falling onto it. A roof is classified as fragile if the bag passes through the roof assembly.
If the bag is retained on the test assembly and no other drop tests are carried out, the assembly shall be classified as Class C non-fragile assembly. Profile 6 sheets meet this requirement.
When tested in the critical frequency range of 100-3150Hz, Marley Eternit profiled sheeting achieves the following mean airborne sound reduction:
Profile 6 single skin 26 decibels
The minimum breaking strength for Profile 6 sheets is defined under BS EN 494. The minimum against grain breaking load (purlin to purlin) for Profile 6 is 4250N/m. The minimum with grain bending moment at rupture (ridge to ridge) for Profile 6 is 55Nm/m.
The approximate installed dry weight of single and double skin profiled sheeting with fixings and the required side and end lap is as follows:
Profile 6 single skin 17.0kg/m²
External fire exposure: the sheets have a P60 (external SAA) rating to BS 476: Part 3: 1975, and can be classified Class 0 in accordance with the Building Regulations.
Fibre cement complies with BS EN 494: Clause 5.3.4.
When new, fibre cement sheeting has a relatively high moisture content. If humid conditions prevail, damp patches (without formulation of droplets) may appear on the underside of the sheets. This phenomenon is in no way detrimental to performance, and will disappear within 12 months, in the course of natural exposure.
Whilst Profile 6 is watertight, it has the ability to absorb up to 25% of its dry weight in moisture and dissipate it in more favourable conditions. This material characteristic has a significant effect in reducing condensation occurrence.
Effects of chemicals
Over the years chemical and industrial atmospheric pollution will cause a slight softening of the surface of natural finish fibre cement sheets. The acrylic paint finish provides added protection against many acids, alkalis and solvents normally found in the atmosphere.
Where fibre cement is to be used in particularly aggressive atmospheres, with higher than normal concentrations of acids, alkalis, fats or salts, please contact the Technical Department for advice.
Marley Eternit profiled sheets are vermin and rot-resistant, but lichen may grow on the outer surface. For advice on removal, please contact the Technical Department.
Effects of low and high temperature
Marley Eternit profiled sheeting is designed to be minimally affected by frost or climatic temperature changes.
For buildings in which higher than normal temperatures occur, or in areas which are expected to be subjected to sudden changes in temperature, special considerations may be necessary. (Consult the Technical Department for recommendations).
Thermal and other movements
The amount of movement is negligible, but it is necessary to provide movement joints in association with the structural framework. (For details of movement joints, please see the Profiled Sheeting Design Guide) The co-efficient of linear expansion for profiled sheeting is 8 x 10-6m/mK.
Marley Eternit profiled sheeting has only low thermal conductivity when compared with other sheet roofing products. This serves to reduce heat build up in summer and heat loss in winter.
Thermal conductivity (k) = 0.48W/mK.
Thermal transmittance (U value)
When constructed as detailed in this compendium, all insulated systems will exceed a U value of 0.25W/m²K. (This is the standard U-value required by Building Regulations Approved Document L2 for roofs with integral insulation on buildings other than dwellings.)
Marley Eternit profiled sheeting may be regarded as having a normal life of at least 50 years, but the durability of the fixing accessories should be taken into account.
Atmospheric pollution is not normally sufficiently concentrated to be harmful. Measures should be taken to prevent corrosion of the fixing accessories, e.g. by the use of plastic washers and caps.
Marley Eternit profiled sheeting is resistant to most forms of atmospheric attack but with age becomes less elastic and a small deflection will be experienced, which may make it less resistant to impact. Its transverse strength, however, is maintained