A company in Dubai is making headlines with its latest project, to erect an inflatable balloon that not only resemble the empire state building it can also accommodate at least a thousand adults. In order to set the record straight the inflatable empire state building must stand at minimum 380m from the ground level and allows 1000 or more adults to fit inside it for a period of 24hours, and when deflated it can be shipped or air flown easily. What kind of material is suitable for this inflation building? answer with the least expensive and high durability wins.
Mylar! That's what you use for blimps, and this is a blimp of sorts. More or less cheap, darn light, and good at retaining air.
While Mylar might make up the bulk of the building, it will need to be reinforced at critical locations in order to stand and resist forces such as wind and shifting loads inside as people walk around (much less go up and down stairs or an elevator).
The main problem with fabrics (which is what this building will be made out of) is they are strong in tension, but not so much in compression. So to help out, and assuming much of the structure is mylar tubes, there will be reinforcing patches at joints such as corners, where floors meet walls and so on. There should also be grommets installed in the patch material so that guy wires or tensioning cables can be attached and tightened in order to provide reinforcement against shifting forces and loads. These cables will be in "X" patterns along the walls and under the floors in order to prevent the structure from shifting too much (otherwise, you will end up with the world's biggest bouncy castle...). These reinforcing patches should be made of very tough materials like Kevlar, Spectra 100 or (assuming you have an unlimited budget) synthetic spider silk (which is 17X stronger than steel in tension per unit weight).
Much of the air handling system used to inflate the structure will need to be made of this sort of material, since the amount of high pressure air needed to inflate the structure and keep it in tension will create a great deal of pressure in the hoses and piping. If we assume that this is a "real" building, given the need to house 1000 people for a 24 hr period minimum, then some consideration must be given to electrical conduits and plumbing as well. Non conductive plastics can work for electrical conduits, but the conduits, electrical fixtures and plumbing will also need to be "hung" on the reinforcing patches which also hold the tensioning cables and provide strength to angles and corners of the building.
Don't forget to bring your patch kit when you visit....