The most efficient and effective method of controlling condensation is to provide natural roof space ventilation and to mechanically extract high levels of water vapour at the source. The Wienerberger Sandtoft range of ventilation products provides cost effective and discreet roofspace ventilation. Products include eaves ventilators, concealed tile, ridge ventilators, top abutment ventilators and gas ridge vent terminals. We also offer a range of ridge and tile ventilators for connection to soil vent pipes and mechanical extraction pipes. Concealed ventilators and invisivents are designed to maximise the aesthetic features of the roof by being virtually unseen once installed and can be used for both low and high level ventilation, as well as for connection to soil or mechanical extraction pipes through the use of an optional pipe adaptor and flexible pipe. Specifications Free vent area: 10,000mm2Spacing at low level (10,000 mm2 per m): 1m IntervalsSpacing at high level (5,000 mm2 per m): 2m IntervalsMinimum roof pitch: 22.5 degrees