Rainwater & Roof Drainage
NLS Contractors installs rainwater and roof drainage in Riyadh, Jeddah, Dammam and Khobar and across the Kingdom: roof drains, downpipes, gutters, overflow outlets and the connection to the storm network. Sizing follows the rainfall intensity the consultant sets, under SBC 701. Handover includes roof drainage layouts, water test records and as-builts.
It rains rarely in most of Saudi Arabia, and when it does it rains hard. A short, heavy storm in Jeddah or Riyadh can put more water on a roof in a few minutes than the drains were drawn for. Roof drainage is then judged on one afternoon a year, and that afternoon decides whether water stays on the roof or comes through the ceiling.
The system is roof drains or outlets set into the roof slab, downpipes inside or outside the building, gutters on pitched and metal roofs, overflow outlets and the line to the storm network. Roof drains are set into the slab before the waterproofing goes down, so the waterproofing is dressed into the drain body and the drain is not fitted afterwards.
The consultant sets the design rainfall intensity, and the number and size of outlets follow from it. Overflow outlets are the second line of defence. If the main outlets block with sand or debris, water finds the overflow and leaves the roof by a visible route instead of rising until it loads the structure. Parapeted flat roofs need overflow provisions in particular.
Roof drainage meets other packages at the outlets, at the gutters and at the storm connection. Waterproofing is dressed into each outlet, metal roof gutters on steel buildings sit with the cladding package, and the storm drain below belongs to the underground works. These details are marked on the roof drainage layouts so each package knows where it stops.
Downpipes and gutters are water tested for leaks and flow, and the roof falls are checked by running water to the outlets. The records are signed and go into the handover file. Price depends on roof area, the number of outlets and downpipes, pipe material and whether downpipes are concealed. Lead time depends on scope and the offer states it. Send the roof plans, drainage layouts, the design rainfall intensity, the specification, the BOQ and the site city.
Specifications
- ✓Components: roof drains, downpipes, gutters, overflow outlets
- ✓Connection to the storm network or the point the design shows
- ✓Sizing to the rainfall intensity set by the consultant, with overflow provisions
- ✓Standards: SBC 701 and the project specification
- ✓Tests: water test of downpipes, gutters and roof falls
- ✓Handover: roof drainage layouts, water test records, as-builts
Frequently Asked Questions
Why do roofs in Jeddah and Riyadh need overflow outlets?+
Storms are short and heavy, and main outlets can block with sand or debris. Overflow outlets let water leave the roof by a visible route instead of building up until it loads the structure or enters the building.
Who sets the design rainfall intensity?+
The consultant, in the project specification and drainage design. The installation sizes and builds to that figure and does not change it.
Are downpipes fixed outside or inside the building?+
Either, as the design shows. Internal downpipes are concealed in shafts and tested before they are closed in. External ones are fixed to the facade and coordinated with the cladding.
Can drainage be added to an existing roof?+
Yes, after a survey of roof falls and the slab or deck. Added outlets and overflows need the waterproofing to be dressed around them, and the offer states how that is handled.
Who supplies Rainwater & Roof Drainage in Saudi Arabia?+
NLS Contractors (Northlane Solutions Company) supplies Rainwater & Roof Drainage across Saudi Arabia, including Riyadh, Jeddah, Dammam and Jubail. Send your specification and quantities to info@nlscontractors.com or info@northlanesolution.com for a quotation.