Roof Rainwater Drainage Design

The quantity of rainwater on a roof surface is determined by the effective roof surface in m to be multiplied by the rain intensity i l min.

Roof rainwater drainage design.

The second part describes in detail the steps that. The effective roof area to be drained. According to the chart for 1 8 slope per 12 of pipe for 5 000 square feet of roof area with a 6 per hour of rainfall the required pipe size is 8. The flow characteristics of the gutter system.

The main benefit of inner drains is that the system is hidden from view. To size the vertical roof drain for the same parameters 5 000 square feet of room area and 6 per hour of rain consult table 1106 2 figure 3. Each chapter consists of two parts. The type of evaluation is tailored to a client s needs from a simple check on capacity to a complete design service.

Drainage design specific to location. The dimensions of the rainwater drainage system can be calculated by means of this quantity of rainfall to discharge per unit of time. Drainage of flat roofs overflow weirs rainwater pipes and drains inside buildings siphonic systems. Crm offers gutter and roof outlet evaluation to bsen12056 3 2000.

In the case of flat roofs the catchment area is the same as the footprint area of the roof being drained. The number and position of downpipes. A typical commercial or multifamily residential building will utilize one of the following types of primary roof drainage. To undertake design work the client would typically provide the details of the roof area and proposed gutter system ideally in autocad dwg.

These will drain to somewhere near the center of the roof and down through the building to underground storm mains or a detention pond. Inner roof drains are used on flat roofs and include a low section or channel that collects water and feeds it into a concealed drain that leads to an underground drainage system. To assess the suitability of a gutter system to drain the roof of a building the following factors need to be taken into consideration. Approved document h makes basic provisions for adequate disposal of rainwater from roofs and paved areas minimising the risk of blockages or leakage and ensuring access is provided for maintenance.

Walls that drain onto a lower storey roof can increase the effective roof area by around 50. Inner drains are resistant to freezing but can require careful maintenance to prevent problems. This applies for rain falling vertically or if it falls at an angle when blown by the wind. It is important for architects plumbing engineers and civil engineers to work together to design a system that will properly drain rainwater from a building and site.

When designing a roof consider how rainwater will impact both roof and upper floor walls and how this water will be drained collected and disposed of. For pitched roofs the catchment area would be the same as the footprint area of the roof being drained for rain falling vertically.