A new, world-class horticultural destination in the north west, the RHS Welcome Building boasts arrival halls, learning facilities, a café, plant centre and gift shop. The exciting project also involved hard and soft landscaping and the creation of a new 4,750m2 lake. The building has high-quality finishes and a glulam timber roof structure that has no bearing on any external wall.
Striking timber roof
The 100m x 30m glulam timber roof is innovative in that the whole structure has no bearing on any external wall. It is constructed from different timber components, including tubular glulam columns, timber diagrid cassettes as well as cross laminated timber panels. Creating a tree-like effect, the glulam ‘branches’ rest on 16 reinforced concrete columns. Measuring 3850mm x 300mm in the centre and tapering to 200mm at the ends, these glulam ‘branches’ support the whole roof.
We worked with timber specialists, Hess, to assemble the glulam cassettes onto the concrete columns, which were bolted on via the glulam branches over 10 lifting stages. The bolts that attached the frame cassettes to the columns had only millimetre tolerance for error, and in a testament to our engineers, the different elements of the complicated build fitted perfectly first time.
The timber roof structure was delivered to site pre-treated and finished. However, the timber would remain open to the elements until the large roof lights could be installed. This time spent open to the elements could have affected the timber’s final look and finish, so BAM worked quickly to install the roof lights and protect the timber. We also worked closely with Hess to find a solution to any potential timber imperfections, which included re-sanding and applying a special coating on the glulam.
The Welcome Building Centre includes two large glazed skylights, one 6m wide by 54m long, and another 18m by 12m, which allow maximum natural light into the building. The rooflights are fritted (finely pourous) to prevent the building from overheating.
Brise-soleil on the outside of the building also contribute to keeping the building at a comfortable temperature.