Product / system manufacture
CRM Rainwater Drainage
Unifold gutter lining system
The Unifold gutter lining system has recently been installed within five valley gutters, totalling more than 700metres, on the roof of the Argos Distribution Centre, Castlegate, Wolverhampton.
The facility, operated on behalf of Argos by Wincanton, had experienced severe stormwater ingress due to the overwhelming of the existing gutters and outlets, causing severe damage and disruption.
The roof had been over-sheeted several years ago and the existing gutters were fitted with a continuous plastics liner at this time. This liner was not lying flat due to expansion and contraction problems, leaving raised areas within the gutter. This further reduced the available capacity and contributed to the problems being experienced.
Ampteam Ltd, along with rainwater drainage experts CRM Rainwater Drainage, were invited to propose a solution to the problem.
• Survey and design
Following a survey by Ampteam and CRM, a design solution was provided for the gutters. The existing gutter had insufficient capacity, and any modification to the roof at the eaves position to enlarge the gutter was not an option. Therefore, the design solution had to make use of all of the available space within the eaves cavity.
The situation was complicated by the need to control works on the asbestos cement gutters on a building that was constantly in use. This, in turn, meant that no extra outlets could be introduced and the existing outlets could not be enlarged.
The solution involved the installation of a multi-hinged Unifold gutter, fitted and sealed to the underside of the roof sheet in order to maximise the gutter capacity, combined with specially designed siphonic outlets.
As the eaves conditions varied along the gutter runs and within each gutter, and access was tight, the Unifold was supplied with seven hinges. This facilitated a relatively easy installation under very difficult circumstances.
• Siphonic outlets
The Unifold gutter was also provided with factory-fabricated side boxes to house the unique siphonic outlets that were designed and tested by Dr Malcolm Wearing of CRM Rainwater Drainage.
Although the capacity of the gutters had been increased to the maximum given the existing roof conditions, these siphonic outlets – manufactured and installed by Aquaphonixs Ltd – were essential to improve the drainage performance of the existing outlets and to allow the system to function without any additional outlets.
Fan-shaped, semi-circular siphonic outlets with an offset 100mm diameter tailpipe were specially designed to fit inside the Unifold side boxes and into the existing 150mm diameter outlets.
The siphonic outlet tailpipes were connected to flexible tubes, sleeved into the existing plastic downpipes.
The custom-made outlets were optimised and tested in laboratory conditions, and proved to provide a capacity of over 27 litres/second, ten times the capacity of a standard 100mm diameter outlet.
Calculations to prove the design solutions of both Unifold gutters and siphonic outlets were provided by CRM Rainwater Drainage.
The Unifold gutter system was installed by approved contractors Traditional Structures Ltd who, due to the relative complexity of the contract, originally forecast a period of seven weeks to complete the installation.
First class organisation, excellent site personnel and attention to detail by both Traditional Structures and Ampteam Ltd meant that the installation was completed in just over four weeks, with no disruption to processes within the building.