The Gateway flats are entirely new student accommodations in Lincoln, which were originally conceptualised by the Kier Construction Group. After careful negotiations with the developer, the build was temporarily mothballed due to the fact that the project exceeded budgetary limits.
Flood Precast was contacted to analyse the precast concrete proposal with an aim to reduce the overall costs to the client and begin the actual construction.
The original design encompassed 13,800 square meters of hollowcore concrete which was 150 millimetres deep. This consisted of no less than eight levels of steel framing and six stair cores to serve seven stories. Schematics of the ground-floor footprint and the roadside elevation were likewise provided.
Drawing of ground floor footprint and road side elevation during construction.
There are several reasons which were presented to the Kier Group in regards to the commercial, design and construction benefits experienced through the use of Flood Precast Super Wideslab as an alternative to Hollowcore. Let us examine a handful of the most relevant.
A Reduction in the Steel Required
Each of the 458 bedrooms were individually serviced by a bathroom pod. The opening through the floor of these units was 500 square millimetres. To accommodate the aperture on the original 1.2-metre hollowcore design, each opening was trimmed out with two structural members. Each was typically six meters long and 500 millimetres wide.
The Flood Precast Super Wideslab configuration was able to be arranged so that a 2.4-metre unit could be positioned at each pod opening. The openings could then be managed with this 2.4-metre width without the use of any additional trimming beams.
There were two notable benefits from this approach. First, this equated to massive cost savings in reference to the reduced tonnage of steel required. Secondly, labour was drastically curtailed. The elimination of some 900 no individual steel members shaved approximately three weeks off of the steel frame erection programme.
Example of pod opes on Flood Super Wideslab with trimmer beams eliminated.
A Class B Soffit Finish Suitable for Direct Decoration
One of the architectural requirements stipulated in the original specifications was for a Class B soffit to be installed within each one of the 458 bedrooms. Unfortunately, the Kier Group found that there were no existing hollowcore procedures which were able to accommodate for this need.
Our Super Wideslab Precast, as an alternative to Hollowcore, is produced by a wet manufacturing process on steel beds. This was a viable solution. Not only could the task be accurately completed, but the 2.4-metre planks reduced the number of visible joints within the rooms by an impressive 50%.
Example of Flood Precast Super Wideslab soffits PRIOR to painting.
Non-Standard Splayed Units
The original building plan consisted of a square block and a curved block. The curved block accounted for two-thirds of the entire floor area. This required bespoke precast units to follow the outline of the building. Forming this in traditional extruded hollowcore meant casting a rectangular unit and after casting cutting the required splay or curve from the plank.
The off cuts need to be costed within the unit rate of the precast plank along with the associated cutting and recycling. Such cuts added to the overall cost of the project (time, man hours and recycling).
However, Flood Precast Super Wideslab is wet cast. In simpler terms, each unit is specifically designed for a certain location within an individual project. Slabs are first marked out on the steel beds by a CAD computerised plotter. This unique shape is then shuttered within the production bed to meet bespoke dimensions. Elements such as splays, notches or curves can be accommodated prior to physical casting. This saves waste, provides a great deal of flexibility and drastically reduces costs.
Building profile that required precast flooring units to suit.
The Speed of the Precast Erection Programme
Time is indeed money in the construction industry. This temporal concern was lessened with the use of 2.4-metre planks (as opposed to their 1.2-metre alternatives). Obviously, these dimensions signified that the total erection time was half of that expected by traditional hollowcore methods. If we assume that a tower crane lifts an average of 30 units per day, the piece count was reduced from 1,875 to an impressive 937.
Based on these same figures, the entire precast erection time frame takes no more than 31 days. This passes on massive savings in terms of time, labour, material and crane operating costs. These are some of the primary benefits which can be seen in a real-time scenario with this unique approach.
Erection of 2.4m wide Super Wideslab with tower crane.
To find out more about Flood Super Wideslab click here.
Download The Gateway Lincoln Student Accommodation case study.
Feedback from Client
From the initial design stages through to the completion of the works on site Flood Flooring maintained a very helpful, professional and competent manner. During their time on site Flood Flooring faced some challenges, all of which were dealt with in a proactive and organised manner. This attitude was consistent throughout Flood Flooring management structure and extended to the operatives on site carrying out the installation works.
Neil Truelove, Senior Site Manager, Kier Construction Central
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Project team:
- Main Contractor – Kier Construction Central www.kier.co.uk
- Architect – Stem Architects stemarchitects.co.uk
