The choice of a rainwater system often comes down to two decisions; domestic / commercial and aesthetics. Half round and square systems are generally used for domestic properties although Ogee and Sovereign provide a more aesthetically pleasing look. The Half round system is available in 75mm for situations such as sheds or garages and 150mm for commercial applications. As well as 150mm half round, Polyflow deep capacity gutter is also available for commercial applications. Sovereign and Ogee can be used on commercial applications although flow requirements should be checked. > As part of our continued product development initiatives we are constantly introducing new products and updating our existing ranges, hence our rainwater range now incorporates seven different systems to cover all installations from domestic to commercial to industrial. These seven systems provide a variety of profiles and capacities ensuring that every installation is catered for whether it is a modem streamline dwelling (Sovereign) or an industrial property (150mm half round). A comprehensive range of fittings to provide the specifier and installer with a complete roof drainage solution accompanies each rainwater profile to give Polypipe an unrivalled product range. All rainwater products are manufactured from PVCu in accordance with a Quality Management System to BS EN ISO 9002 (certificate no FM00318) >

The aim of designing a rainwater system is normally to achieve a balance between the cost of the system and the frequency and consequence of possible flooding. The capacity of the gutter should be designed to provide adequate disposal of the heavy rainfall usually associated with summer thunderstorms. A simple methodology for roof drainage design is shown below but for further information regarding roof drainage refer to BS6367:1983 Code of practice for the drainage of roofs and paved areasӔ. > To determine the profile of gutter required it is now necessary to define three criteria: How many...

Due to the infrequency of extremely heavy rainfall in the United Kingdom, it is almost impossible to design a cost efficient rainwater system to give complete immunity from flooding and overflow. Because of this it is generally regarded as normal practice to design rainwater systems using a rainwater intensity level of 75mm per hour. To calculate the gutter requirement, multiply the E.R.A. (m > 2 ) by a factor of 0.0208 (75mm/hour divided by 3600 seconds/hour) to give the flow rate in litres/second (l/s). Once a flow rate has been determined use tables 1 & 2 (below) to select the required gutter...

Table 3 Product Compatability Chart 75mm Gutter Half 112mm 112mm 117x75mm 130x70mm 117x75mm Size Round Half Round Square Polyflow Ogee Sovereign 150mm Half Round 68mm 68mm Round Round Downpipe 50mm 68mm 65mm 68mm 65mm 65mm size Round Round Square Round Square Square 110mm Hepworth No Yes Yes No No No Yes Osma (Wavin) No Yes No No No No Yes Hunter No Yes Yes No No No No Marley Yes Yes (Clipmaster) No No No No Yes Geberit (Terrain) No No No No No No No Brett Martin No Yes Yes No No No No Flopast No Yes Yes No No No No Marshall Tufflex No Yes Yes No No No No Freefoam No Yes No No No No No Table...