What is the purpose of the structure/project?
A new Roman Catholic Church with exceptional acoustics, despite the exterior weather conditions.
What was the brief to the Architect?
The brief to the project team was to design a long span octagonal roof, acoustically insulated from rain and hail sound effects. The brief included the design of a complex shaped and vaulted ceiling below, also designed with specific acoustic properties. A specialist Acoustic Consultant was employed to assist in the form and specification of the roof coverings as well as ceiling below. A Sound Reinforcement Consultant also advised on the church space and acoustic ceiling above.
Was the project envisaged in steel from the start? If not – why was it built in steel in the end?
Yes. Early design options for a tiled roof were discounted at the inception of the project.
Give a brief description of the structural framing. What type of sections were used (e.g. hollow, cellular, I-beam, etc.) and why?
The roof design was made more complicated by the planned shape of the building itself, not being asymmetrical octagon but rather an adjusted one. This design could not rely on pure symmetry and a lot of effort was spent with the Structural Steel Detailers, KRU Detailing, to draw and detail all the components.
The fact that the springing point of the roof was at 6.95m above the slab level, and that the concrete work at roof level comprised of two complex rings of reinforced concrete “loops” supported on linked column frames, required planned tolerance between the steel/concrete face and much survey effort was undertaken by the builder and Sub-Contractors to ensure a first time fit at the high level.
The ceiling below was also required to be supported on a secondary structural steel grid. The centroid and shape of the ceiling profile did not match the shape of the roof, with slopes and acoustic performance requiring support work, positioning the steel grid well away from trusses and cladding supports, considerably over-complicating the design and erection process.
Give a brief description of the cladding process (complexity, difficulty, innovation etc).
The roof cladding, on the advice of a multidisciplinary team led by the Engineer, was for lightweight concealed fix roof cladding, designed around the partly asymmetrical octagonal roof, built tightly over a special taped gypsum sandwich layer, specified by the Acoustic Consultant, the sound damping system was to be tightly below the metal cladding.
This design was configured to damp excessive noise from rain and hail during the future church services. The gypsum was in turn supported on its own metal gridwork, all fixed to the steel roof at the highest level. Spans and spacings were critical, with the roof cladding requiring a different support work spacing from the gypsum layers below.
The acoustic ceiling below was designed to a complex shape, in turn requiring a different grid configuration and shape from the girders and supports above.
The ceiling required movement and control joints as part of the design specification, with the metal grid work between steelwork and the acoustic ceiling itself being “weakened” at the critical positions of the larger radial joints to ensure the performance of the actual ceiling joints below. The ceiling would not be readily accessible from below for cleaning and maintenance purposes due to the configuration and layout of the seating for the congregation.
Were there any challenges in the fabrication of the project from the Engineer’s design – if yes, please tell? Tell more about fabrication and erection process if it was complex, difficult, innovative etc.
The sheer complexity of the roof, the two independent levels of structure (at cladding level and much lower down at acoustic ceiling level), the substantially different shapes of the two structural elements, the moderately long spans, structural heights, moderate-high loads, and all design complicated matters.
The site of the new Church has a severe grade of around some eight percent, also had planned stepped terraces. This required quite complex construction arrangements, affecting the delivery of materials, site storage and the steelwork erection process itself.
What is special/ unusual/ innovative/ aesthetic about the steelwork/cladding in this project?
The roof cladding itself required to reflect the “look” of old weathered copper-roofed churches, and the complex vaulted and shaped acoustic ceiling below were conceived by a specialist experienced ecclesiastical Architect and executed by the project team, led by the Structural Engineer.
A specialist Acoustic Engineer was consulted to assist with shape and material of the roof cladding as well as the ceiling below. The requirement for special acoustic cladding at roof level, with the unique acoustic shape and material at ceiling level below, provided quite a challenge that was successfully solved by the Designers and Contractors.
The rainwater goods and concealed downpipe pipes required intricate detailing and planning. The gutters were designed as part of the external cladding shapes and the collection and vertical reticulation of stormwater integrated into the frame and cladding of the building. The downpipes are hidden in the structural support columns but linked back to the gutters, which in turn, were provided with long life urethane coatings. An overflow capability was built into the gutter design to cope with larger design storms and hail precipitation.
How did the project team work together (e.g Contractor involved early, challenges/ease of communication etc.)?
The Contractor was consulted immediately after tender. The tender documents were especially drawn up by the Quantity Surveyor firm, Norval Wentzel Steinberg, around the complex shape, and working drawings were included in the documents (for the upper-level structures only – the ceiling supports were added post tender). A pre-tender qualification process ensured a trim tender pack of experienced steel contractors.
Prior to award of the contract, the Sub-Contractor, Central Welding Works, and their project team was interviewed about the project, complexities, ceiling support grid, and the tight programme. The Engineer had prior significant experience of contracting work from Central Welding Works and this was a material condition of the award itself.
Close planning between the Engineers and Structural Steel Detailers, resulting in several important meetings, and then the presence of an impressive three-dimensional (3D) drawing back to the team (Employer, Architects, and Contractors), ensured a multilevel approval process, all done quickly due to a rapid and compact construction programme.
The team realized the complex and special requirements of the roof upfront and the need to get it right from all angles and stages, from start to finish. The shaped vaulted acoustic roof and complicated ceiling elements are probably the most crucial part of a successful building and all aspects of this received priority attention from the whole team, including the Employer, Structural Steel Detailer, and Site Crews.
|Tons of structural steel used||32 Tons|
|Structural profiles used||All Sections|
|Cladding profile/ type used||0.58mm colored GRS Kliplok 700 concealed fix|
|Cladding area/ coverage and tonnage||1,120m²|
|Project Team Role||Company|
|Nominator||KRU Detailing CC|
|Client/ Developer||Rivonia Catholic Church
The Shopz Group
|Structural Steel Detailer||KRU Detailing CC|
|Structural Engineer||Rouillard Consulting|
|Quantity Surveyor||Norval Wenzel Steinberg|
|Project Manager||Rouillard Consulting|
|Steelwork Contractor||Central Welding Works|
|Steel Erector||Central Welding Works|
|Cladding Manufacturer||Global Roofing Solutions|
|Cladding Supplier||Tate & Nicholson|
|Cladding Contractor||Tate & Nicholson|
|Dram industrial painters|
If you were a part of this project, and your company details are incorrect or missing – please notify the SAISC so that the error can be corrected.