RAINWATER MANAGEMENT
Water, water, everywhere E
are common items on the UK news agenda, and while rain and stormwater levels vary from region to region,
the need to manage them effectively is nationwide.
The damage that can be caused by excessive rainfall is well documented. In November 2017, for example, the rainfall equivalent of 200 Olympic-sized swimming pools drenched the small rural community of Coverack in Cornwall, and caused over £1 million worth of damage. To help limit this kind of damage to towns and cities across the UK, there is a growing and ever-present need for effective rainwater management. One way merchants can help with this is to ensure their customers have the right drainage solutions for their projects.
Capacity
The purpose of a rainwater system is to direct rainfall away from the roofed area of a building, using either gutters or down pipes. In order to effectively manage this rainfall, drainage systems need to have the right capacity. “Capacity is dependent on various elements including the amount of per second, how guttering is laid and the number of drainage outlets in the system,” says Steve Skeldon, above ground project manager at Wavin. There is a quick calculation merchants can use to calculate capacity, which is based on the roof plan area and its pitch, which will allow them to advise their customers better about which products they need. See example above. Skeldon says that it’s important to note that a rainwater system must be able to manage more than the expected levels of rainfall, to cater for all eventualities.
How to calculate capacity The roof plan area (length multiplied by width) in square metres x the appropriate roof pitch factor • Shallow (approximately 30°) x 1.29 • Normal (approximately 45°) x 1.50 • Steep (approximately 60°) x 1.87 A = 5m and B = 12m Shallow pitch: 30º
Roof plan area: 5m x 12m = 60m2 Effective roof area: 60 x 1.29 = 77.4m2
“Merchants should also be mindful that, while the type of building may dictate how the gutter is laid, capacity will be By contrast, a straight run can help to maximise the overall capacity of a drainage system,” he says.
Rainfall by region
Different regions, of course, get different amounts of rain. Areas such as Snowdonia, the Lake District, the Scottish Highlands each get more than four metres per year. Height above sea level and distance from the coast are two big factors affecting rain levels. “Understanding regional differences in rainfall is therefore essential when advising on rainwater management systems, and the greater the amount of rainfall, the higher capacity of the system required,” Skeldon adds. “Merchants should keep this in mind when ordering stock, so customers can get the drainage system they need as quickly as possible. Heavy snow can be just as bad as heavy rainfall. Where there is a possibility of snow loading in areas prone to excessive snowfall or even very high winds, it is important to bear in mind that reducing the distance between brackets to a maximum of 600mm apart is worth considering.
Average annual rainfall by region:
Northern Scotland: 1700mm Eastern Scotland: 700mm – 1500mm Western Scotland: 1000mm – 3500mm Northern Ireland: 800mm – 2000mm Wales: 1000mm – 3000mm North West England & Isle of Man: 800mm – 3200mm
North East England: 600mm – 1500mm Midlands: 600mm – 1000mm Eastern England: >700mm Southern England: 550mm – 950mm South West England: 700mm – 1000mm
Skeldon says that high capacity drainage systems are becoming increasingly popular with housing developers as a means of improving process.
Capacity concerns
“Many housing developers are opting for gutters with a higher capacity than needed so that they can reduce the number of downpipes they require. This means the installation process is quicker, keeping time and cost down during the building process,” he says.
likewise shaping product development. “Features such as the Flexiclip, for example, makes connecting gutters to guarantees a strong, watertight joint. Also, the hydrodynamic running outlet rate, prioritising both time productivity and product quality.”
As the UK gets higher volumes of rainfall year upon year, the need for effective rainwater management increases. Skeldon continues: “Builders’ merchants need to be prepared – not only with the right products, but with the knowledge and information necessary to combat the growing problem.”
Products that allow us to manage our rainfall better are becoming more important.
BMJ January 2018
21
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
