ACO RAINWATER OUTLETS CARE AND MAINTENANCE 1. The current standard relating to flat roof drainage design is BS EN 12056, which replaces BS 6367. 2. ACO rainwater outlets are manufactured in cast aluminium. The correct choice of outlet in relation to roof covering is important when selecting a rainwater outlet. ACO rainwater outlets use a mechanical clamping process to secure the water proofing membrane and are suitable for connection with mastic asphalt, bituminous felt and single ply roof coverings. Where an aluminium outlet with lead sheet is intended there may be a risk of bimetallic corrosion, the severity of which is determined by atmospheric pollution or air/saline content (coastal applications); in these conditions cast gunmetal is to be used. In all instances of copper roofing or slate roofs using copper nails a gunmetal outlet must be used. It is not widely known that rainwater run-off from cedar shingles will cause corrosion of aluminium. 3. If one only rainwater outlet has been installed to drain an enclosed flat roof, provision must be made for blockage by providing either a second outlet or overflow arrangement. 4. Rainwater outlets fitted with raised gratings are less prone to blockage than outlets fitted with a flat grating. Flat gratings fitted to outlets used in unsupervised areas will be at risk of blockage from wind blown debris, plastic bags, dead birds and play balls. Establish a routine inspection regime of not less than two inspections per year, Spring and Autumn. Cleaning merely requires removal of waterborne debris. 5. Upon completion of a roofing contract and prior to handover, all outlets should be inspected for missing fixings. Replace missing studs, nuts or bolts. Check the correct fitting of clamps and gratings. 6. REMEMBER - The flow performance of ACO rainwater outlets may become impaired if outlets are not inspected at least twice yearly preferably in Spring and again in Autumn during the period of leaf fall. Impaired flow will result in standing water and greater than designed for roof loadings. Flashings may become submerged and water ingress will result.
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