THE HENNESSEY DOME GOES UP THIS WEEK! This week Hennessey will experience a major construction engineering event. Wynn construction along with South Industries will inflate the largest soft sided dome ever built. Now, let me explain. Normally these dome structures are constructed with concrete walls, then a dome top is inflated using air pressure. Concrete is then sprayed on the underside in layers creating a solid concrete top. In Hennessey they are doing it a little different. In this building they are inflating the walls and roof all at one time with no pre existing concrete walls! So in a matter of hours the entire structure will be up in full scale. This technique is known as an air-form, air pressure holds a vinyl form in place while concrete is applied. But this is the first time it has ever been done on this scale anywhere. Here’s the plan. A few weeks ago they poured a concrete footing that is several feet deep, and 180 feet across. On top of that they installed a steel angle iron fixture and attached the bottom of the vinyl wall to it. Next they constructed a large steel ring that is actually the top of walls. They attached the top of the vinyl wall to this ring. Next the vinyl roof is attached to the outside of the steel ring. All of the equipment that will be needed to complete the inside of the structure has to be inside the ring before the roof goes on. This includes all of the steel, and heavy equipment, like fork lifts and aerial lifts. As soon as they start to inflate the building the only way in is a small walk through door. This is necessary to maintain air pressure to keep the structure inflated. Using giant fans, air is blown into the air form, the pressure inflates the roof first, and then it lifts the top ring and walls. Think of it as a giant vinyl swimming pool upside down! After the inflated structure is up the contractor will spray foam insulation on the inside of the entire building. Next they will erect a wire/steel skeleton on the inside. The final step will be to spray concrete in layers on all the inside walls and ceiling creating a solid concrete FEMA rated storm structure. It will take about 60 days to complete the inside structure. Then they will cut a large opening to remove the heavy equipment that will eventually have an overhead door. The plan is to inflate this structure mid-week, and we will be there and bring you all the details. This is the first of many updates on the construction of this amazing building so stay tuned for the next episode of Were Going In!