Sliding Glass Walls

By Bud Dietrich

The sliding glass wall links inside and outside physically and visually.

Connecting Inside to Outside and Outside to Inside
One of the great promises of architectural design for the last century or so has been the idea that we can blur the distinction between inside and out; that we can expand the interior and make our homes as large as all outdoors and that we could bring the outside in. This promise started in great part due to the ability to manufacture large sheets of glass.  And recently we’ve seen even more chances, with the introduction of better doors, to really blur that line.

Architecturally, where once we had walls only of masonry or wood with smaller, punched windows, we now have walls of glass and metal.  And while previously we could have a portion of our glass walls open when weather permitted, we now can have whole walls of glass that open up so that a room size is no longer limited to where the exterior wall is. With advances in manufacturing techniques and technology, these large glass walls can have excellent thermal resistance properties, withstand high winds, hold up to flying debris and be easily operated.  To achieve a true blending of inside and outside requires that we design these glass walls to be just that: walls of glass, not just doors of glass.  To do this we need to make sure that the top of the glass wall reaches the ceiling height.  Otherwise the bit of solid wall between the ceiling and the glass will act as a barrier to an uninterrupted space.  The other design consideration is to make sure that the sill, or threshold, doesn’t create a barrier to the outside.  Some glass door systems are better at achieving what is essentially a “zero threshold” than others.  So let’s look at how 3 types of exterior glass door systems function and what their relative advantages and disadvantages are.

The Sliding Glass Door
This type of glass door has been around for quite a long time, especially in a two panel configuration.  The central design configuration is to have panels of glass slide past each other when opening or closing the door.  To create a large glass wall in lieu of a sliding glass door simply takes adding more panels.   Of course, this means that the overall thickness of the system, with its multiple panels all sliding alongside each other, requires a wider sill track.  In fact, it wouldn’t be unusual for the track to be 12 or more inches wide.  And, depending on manufacturer and code requirements, the track can be as much as 3 inches tall.  So while the overall size of the door will provide a large opening that blends inside and outside, the details of the door’s frames can be a hindrance to achieving a totally seamless blending.

The Lift-Slide Door
A variant on the traditional sliding glass door system is the lift-slide door.  These types of doors are supported from above rather than from below.  While this system uses multiple panels set parallel to each other, the track system dimensions are minimized.  In fact, the tracks for a lift-slide door are typically recessed into the floor so that only a small metal guide sits above the floor plane.

A newer version of the lift-slide door is a system that consists of multiple glass door panels that, when closed, all sit in the same plane.  To open the wall up one only needs to slide each panel left or right.  Each panel slides in the same track until reaching the sides.  At this point, the single track splits into multiple tracks so that each panel can slide past its neighboring panel.  This all works much like a railroad track that, once the single track reaches the train station, can split into many parallel tracks so each train can reach its terminus easily in the least amount of space.

The Folding Door
A folding glass door system provides for the widest opening possible because the door panels, when open, are perpendicular to the exterior wall rather than having door panels stack one on top of the other. And because the door panels fold open and closed in an accordion like fashion, the track for a folding door system can be quite narrow.  In fact, the bottom track is merely a groove that keeps the door panels in place without providing any structural support. 

When fully closed, a folding door system has all of the panels placed in the same plane so that there’s no overlapping of panels. This can be an important design consideration as you may want the glass wall to be flush and planar rather than a system of stacked components.

With the many products that are available, it really is important to do research into which glass door system you’ll use. Each manufacturer’s system will have different features and operate in different ways at have a different price point. Visiting showrooms, operating these big doors and looking into long term maintenance are some of the things you’ll want to do before settling on which door system to use.

04/26/2014