Ok, the job was complex. But a life-size mock-up to iron out Great Ormond Street鈥檚 glitches? are they mad?
There is nothing new about building mock-ups to see how they stand up to wind and blasts, but what about having a dummy run to work out the anomalies before you get to site?

It seems extravagant, but that was the drill for a complex section of the Great Ormond Street Hospital in London, and it saved 拢300,000, according to Ken Bright MCIOB, construction manager for English Architectural Glazing, the specialist building the exterior.

There are many material interfaces on this job: stack bonded brick, aluminum feature channels, glass louvers, curtain walling, window profiles and roof membranes, to name a few. The project team wanted to see how they fitted together before committing to the real thing, so, for approximately 拢80,000, it constructed a life-size model at EAG鈥檚 factory in Suffolk.

EAG built the mock-up last year and started on site at Great Ormond Street in May. They won鈥檛 finish until August, but Ken Bright believes the mock up taught them invaluable lessons. Join Ken in a short virtual tour of a few of the mistakes the mock up helped them avoid.

1. Miscalculations

鈥淭here was a problem with the original deflection calculations for these glass louvres. Once installed on the mock-up, we checked the rigidity of the suspension system 鈥� the vertical rods 鈥� and found they would whip back and forth more than initial structural calculations indicated. The complete design was unique and as such made structural modelling difficult to apply. Anyway, the solution was to attach a fin made of toughened glass to each suspension rod. This increased its stiffness. If we鈥檇 left it to find out on site it could have meant weeks of delay, for scaffolding, rescheduling, and ordering the glass for the fin.鈥�

2. Blind spots

鈥淚t doesn鈥檛 look like much if you are walking by, but what you see here as an indent on the brickwork is actually a gutter, and was typical of some of the blindspots we discovered in the design. It鈥檚 one of those little complications that just don鈥檛 show up until you build. If we had discovered this on site, we鈥檇 have had to stop, design the gutter, have it bent to fit, powdercoat it and fit it, thus disrupting the programme.鈥�

3. Watertight

鈥淭his is a vertical set out for the brick work, filled with a specially extruded aluminium channel. So what? Well, it鈥檚 just one example of how were able to get the material connections right to millimetre accuracy. And it had to be waterproof. We co-ordinated the waterproof line for the elevations and detailed effective junctions between the trades without having to do off-site water testing. Bringing the trades together at this stage also allowed us to agree areas of responsibility for waterproofing. We could also test sealants and membranes for compatibility, performance and stain migration. Remember, we had nine material types here.鈥�

Source

Construction Manager