There’s no denying that rainfall in the UK is increasing. Not only is the country getting wetter, but there’s been a change in the nature and frequency of the UK’s rain. This erratic and unpredictable rainfall is causing us to think differently about the way we approach a build – from location and proximity to water and flood risk areas, to the depth and quality of our rainwater products.
Plan, plan, plan
Every self-build project is unique, and so too are the requirements and considerations. A successful rainwater system doesn’t just rely on the right number of downpipes and guttering depths, it works hand in hand with well-appointed, below ground drainage.
So consider whether you’re connecting to a private or public sewer, a soak-away or a combined sewer. Initially, plans need to suit the depth and location of the underground drain or sewer that you intend to connect to; generally this needs to be at least 0.8m lower than the ground floor level. Once this is confirmed, review the number of pre-set, and any additional, downpipes and their positioning. As the water must be carried away from the property, it is recommended that a downpipe doesn’t run onto an impermeable surface – tarmacadam for instance. The pipe should either be positioned so that the water flows to the drainage channel or soak away, or should simply soak into the ground (infiltration).
Balancing practicality and aesthetics
Keeping downpipes away from the ‘face’ of a property is widely considered to be best practise, aesthetically. In the main, downpipes are positioned down the side of the property so that they don’t detract from the visual appeal of the building. However, this means that the water has to flow around a corner. This can cause a slight reduction in the flow rate of the water when compared to a standard installation of a straight line and downpipe. This is something to bear in mind but in reality it has little impact on the performance of the system.
With storm water run-off becoming a regular occurrence, roof and roofline companies have had to react. This has led to the development of products designed to handle a much higher flow rate than a standard guttering system. The market leading flow rate is around 10 litres per second, while also achieving a capacity 10 times that of a standard half round gutter and at least five times more than a standard deep system.
Manufacturers have also seen a move towards ogee and deep gutter profiles. As would be expected, both Scotland and Ireland are the biggest users of deep and ogee styles but as the nature of rainfall continues to change, a shift in buying trends across England and Wales is starting to mirror this.
With increased capacity comes an increase in weight and pressure on the fixing system. So in line with the increase in depth, is an increase in strength. So be aware of the strength of your preferred system, could it withstand a gutter full of water, ice and snow? Also, bear in mind that it isn’t just the system and the fascia bracket itself, look at the quality and condition of the fascia to which it will be fixed.
The pitch of a roof can have an effect on the way the water enters the gutter. In simple terms, the higher the pitch equals less volume of water (technically) but the flow rate is quick. In contrast, a low pitch would have a higher volume of water that flows at a steady, slower moving rate. Again, consider the area and pitch of your roof when choosing gutter depth and the strength of your system.
Tiling trends vary from location to location and are largely dependent on the style of property. Clay, slate, cement, and ‘green’, alternative roof tiles are all widely available but the factors to look out for are the texture of the material and the shape of the roof tile.
Large, flat, smooth tiles will inevitably cause quicker surface run-off, while textured, contoured roof tiles will be slower. Faster run-off has the potential to cause the water to overshoot the gutter profile, therefore careful consideration should also be given to the depth of the tile – not overhanging, nor falling short of the profile. When choosing your tiles, factor in the pitch of the roof – the higher pitched, faster flowing roof design coupled with large, flat smooth roof tiles would need a strong and deep gutter system, and could even require additional downpipes.
So when you’re planning a self-build, think of the bigger picture not just the products and services that are needed at each stage of the development. Forward thinking will allow you to create an effective and well-performing property capable of withstanding the demands of today’s climate.