Roof is designed with a dual pitch as standard providing positive shedding of rainwater and can be designed to incorporate hips, valleys and overhangs increasing the aesthetics of the building. Roof systems are designed in accordance with SANS 517:2011 and have a standard dead load of 0.1kPa and live load of 1.5kPa although this can be upgraded for high risk environments such as snowy areas where further load is required. Due to the materials utilised the roofing system is non-combustible and will not contribute to the spread of fire.
Pre-engineered light weight steel trusses are assembled from 89x41x0.8mm “C’’ sections made of ZincAl (AZ150) or galvanised (Z275) high tensile G550 steel. Trusses are transported flat pack and assembled on site to maximize transportation.
Steel “top hat” purlins are fixed on top of trusses spanning the length of the building to tie the roof system together and allows for fixing of roofsheets. Purlins are assembled from 40x10x0.5mm made of ZincAl (AZ150) or galvanized (Z275) high tensile G550 steel.
Roofsheets formed from 0.58mm ISQ300 (Z200) pre-painted hot-dip galvanised steel Chromadek and available in a range of standard colours. Roofsheets are 765 Widespan type as standard but are also available in 10.5 Corrugate, and 686 IBR, these are fixed with 5.5x65mm hex head galvanised type self drillers with EPDM washers. Pre painted hot-dip galvanised steel flute closures or polyclosures made from cross linked, closed cell, expanded polyethylene are used to create a weather tight seal and also prevent dust, draughts and birds from nesting in eaves and ridges.
PVC-U D-Shape Gutter and downpipe system can be provided. Generally one down pipe will be provided for every 110m² of roof area, brackets every 750mm with couplings and corners provided where required.
50mm foil back Isotherm can be provided to insulate the roof for areas with extreme conditions. With a density of 10kg/mᶟ there is a 72% reduction in downward heat flow and a thermal resistance of 1.10(m²k)/W, a noise reduction coefficient 0.6 is also achieved. Isotherm is also available in 40mm, 75mm and 100mm thicknesses.