Willmott Dixon construction manager, Chris Evans, on the race to build a new secondary school in Sevenoaks which opened earlier this month (September) and how keeping more earth on site saved time and money.
Describe the project
Trinity School Sevenoaks is a four-form per year entry free school for secondary education, complete with sixth-form facilities. We completed and handed it over for the start of the new term a week early. Although the build was generally straightforward, handing over for the start of the new school year was challenging. The new building will accommodate 640 pupils between 11 and 16, plus a further 190 pupils at sixth form.
Vital statistics
The school was built under a design and build contract by Willmott Dixon. The contract was £19.6m – £16.9m for the building, and then £2.7m for the external works. The contract sum was £22m, but this did include the cost of a temporary school and extensive external works for two schools. It was procured as part of the Scape framework and funded by the Education Funding Agency. Consultants include Bond Bryan Architects and MLM Consulting (structural, M&E and external work).
What did the works entail?
The contract involved clearance of the former secondary school on the site, extensive site works and the construction of the 6,550 sq m school. The building is mainly arranged over three and four storeys and is complete with dining hall sports hall, science labs, class rooms and large theatre/activity studio.
The structure is a mixture of steel and concrete frame and then curtain walling and cladding panels. Willmott Dixon also had to provide a temporary school for those children who had started at the school when it was based in other temporary accommodation on another site.
What was the big challenge?
I’ve worked on other schools and generally the construction side of this was quite straightforward. There’s not really any frills – the building is quite functional in common with most of the new school buildings that came after the halt to the Building Schools for the Future programme in 2010. But there were a number of key challenges.
First, it involved making up time to ensure we completed for the beginning of this term. The contract got off to a late start because of uncertainty over the building of a grammar school on the same site. This got the go ahead later and construction is now underway, but originally the two schools were due to be built concurrently.
The grammar school is an extension of an existing school based in Tonbridge, which will allow it to admit 90 additional places starting with year seven pupils in 2017.
What were the key innovations and solutions?
One of the key issues we had to overcome was dealing with the water run-off. So we built a dry lagoon on site to help with the drainage. The positive effect of this was that we could keep on site more muck than originally thought. As well as this we raised the building by 300mm which also helped. We had to agree this with neighbours and go back for planning permission. It ended up saving us 920 lorry journeys which was great for our neighbours.
Another key development as the project progressed was changing from cross ventilation to single-sided ventilation – which helped save money and provided better acoustics.
What will you take away to other projects?
I’d definitely use the brick slips again and we are planning to use them on the new grammar school. We opted for them for this project not because they were cheaper but to ensure we beat the schedule. The brickwork was scheduled for the winter months and could have been affected by weather.
On the grammar school we intend to use a concrete frame throughout rather than the mixture of concrete and steel. Once up it’s quicker and easier for the follow-on trades to progress and there’s not the acoustic and fire issues you get with a steel frame.
Champagne moment?
Getting the building over early to the client. In the end we managed to give the client partial possession on 50% of the building three weeks early and the entire building one week early. We’d worked pretty closely with them – they had a base on the site. It was a great team effort between us the builders the client and the end user. Being able to move the students in at the start of term made them very happy.
