Modern architecture loves huge expanses of glass. Who wants to be boxed into the dreary darkness of four bare walls when you could commune with nature within a climate controlled interior space?
Most of these expanses of glass exist in the form of either fixed window walls or curtainwalls. I am perplexed by the term curtainwall. When I think of a curtain I think of something that hangs and opens, but curtainwalls are mostly fixed structures with small operable panels on occasion. I get it that the curtainwall hangs or drapes off floor structures in multi-story buildings like a curtain, but they don’t more.
Ok, back to window walls. The typical window wall is smaller in scope than a curtainwall and commonly shows up as a horizontal band of glass with operable windows with single or French doors interspersed. The movable glass wall is similar, but the whole thing moves so that the interior of the building can fully open eliminating any interruption between inside and outside. Damn the torpedo’s, I want to bring the outside climate inside. At least I want to be able to do that when the weather is good. In extreme heat, cold and rainy conditions, they can just stay closed.
There are three typical ways of operating a movable glass wall. The most expensive is to have a fixed window wall mounted on a massive electro-mechanical structure that moves in one piece into the floor or tilts up. I’ve worked on projects like this and the movement part of the project can cost a quarter of a million dollars by itself. The result is not only dramatic in the opening created, but letting guests watch tons of glass and metal move out of the way can leave a lasting impression.
The best known movable glass wall is the sliding door. I’m not talking about the simple patio door in millions of homes that lead out onto decks or patios and are only six feet wide. I’m talking about multi-panel sliding glass doors where each glass panel slides on a separate track. Some sliding doors can have glass panels up to ten feet wide with similar heights. The weight can make them difficult to move so motors, larger bottom rollers or lift/slide mechanisms are added to make the drudgery of moving them less of an Impediment to using them very often. Another shortcoming of sliding doors as a movable glass wall is that each panel needs to be on its own track. A three or four-panel door approaches a foot in depth. The track can be ugly and the wall must grow to absorb this thickness. Many architects I have worked with also go nuts because the glass is not on a single plane and it doesn’t look so wall-like from the inside and outside.
The third and fastest growing solution for the movable glass wall is the bi-folding glass door system. As many as sixteen panels of three to four feet wide glass panels with wood, metal or plastic frames can be joined together with special hardware that allows them to fold up to either end in hinged pairs that gather up like an accordion bellows. There is almost no effort necessary to move them with their sophisticated roller systems, and as soon as the door starts to open the resistance of the weatherstrip no longer exists. The weatherstrip is compression rather than sliding; it is simply out of the equation. All the glass is on one plane and therefore looks more like a window wall and the overall system is no deeper than your traditional patio door whether it is two panels wide or sixteen. With a little planning, you can also turn one or two of the panels into regular swing doors so that you can go in and out through the movable glass wall without opening the whole thing.
2Fold® is a bi-folding movable glass wall. It looks more like a fixed window wall than any other door in the category. This is because the glass-to-glass dimension where sashes come together is only a little over two inches wide. This spaghetti thin section spaced up to 47” apart looks as good as the thinnest fixed window wall AND it has the added benefit of fully opening with the flip of a simple lever . . . the best of both worlds . . . open and closed.