Sliding Glass Doors and Glass Partitions: Divide Rooms Without Closing Them Off

What sliding glass doors can do, and what they cannot

A hinged door knows two states: open or shut. A sliding glass door knows many in between. Open a crack, it lets voices through; closed, it holds back noise and cooking smells noticeably, and the light still travels on. It also needs no swing area, which frees up floor space in narrow rooms.

This gain has limits you should know about beforehand. A glass sliding door dampens sound, but it does not seal like a wall. It shows fingerprints, and beside the opening it needs room for the leaf. If you only want quiet some of the time, you will live with it very happily. If you have to sleep by day in the next room after a night shift, you may need a different solution.

In our example the day looks like this: in the morning the door stands open and the east light reaches all the way into the kitchen. At nine it glides shut. In the evening the study becomes part of the living space again. For the broader thinking behind such apartments, see the article Half-open instead of open.

A good sliding door is a wall that decides afresh every day whether it wants to be there.

Doing without has a cost counted in minutes: the call interrupted by the grinder, the door left ajar for light that lets the noise in too, the room that is never quite an office and never quite living space. A wrong choice shows up later in another way, as a leaf that scrapes, a gap that whistles or a ceiling that was never meant to carry the load. So which systems are there?

The main system types compared

The term glass system covers quite different constructions. The overview below sorts the common types by what they demand of the room and what they give in return.

A glass partition is a fixed, usually floor-to-ceiling glazing that separates two rooms permanently and lets light through. In an apartment it makes sense where a dark hallway or an inner workspace needs daylight and the separation is rarely lifted. The sliding door, by contrast, suits places where the state changes over the course of the day.

In Döbling the wall beside the opening is almost clear, with only a light switch in the way. The couple therefore choose a wide leaf in front of the wall. Moving the switch is a small job; a wall pocket would have been a large one. How such decisions fit into the bigger picture is explained in the article on room transitions. And in what order should all this be planned?

Planning a sliding door system: the sensible order

The most common disappointments arise when the product is fixed first and the room is consulted only afterwards. The reverse order has proved its worth.

1. Clarify the use. When should the passage be open, when closed? Is it about light, sound, smells or sightlines?
2. Check the path of travel. Where does the leaf stand when it is open? Everything on that wall, from the switch to the radiator, is either in the way or gets covered.
3. Clarify the fixing. What carries the weight, the ceiling or the wall? The answer depends on the construction and is checked before ordering.
4. Settle the floor. Does the leaf run with a small guide or a track, and how does the flooring continue beneath it?
5. Sample glass and profile. Always next to the floor, the timber and the wall colour, never in isolation on a table.
6. Plan power and light. Switches and luminaires move out of the path of travel before the cables are laid.
7. Measure on the shell. Glass forgives little. Final measurements are therefore taken only once the screed and ceiling are in place.
8. Allow for lead time. Such systems are usually made to measure, so the order belongs in the realistic schedule of the renovation.

If cabinets or shelves connect to the system, Tischlerkultur, our joinery workshop, family-run since 1935, plans them from the same drawing. There is then no accidental joint between the glass element and the built-in wardrobe, but a deliberately set junction. Next comes the unglamorous question: what actually holds the glass?

Ceiling, wall and floor: what holds the glass

Glass is heavier than it looks. It weighs about 2.5 kg per square metre for every millimetre of thickness. A leaf of 1 by 2.6 m in 8 mm glass therefore comes to a good 50 kg before any profile and fittings, and that load moves many times every day.

If the system hangs from the ceiling, something above it must hold the screws permanently. A concrete ceiling is usually straightforward. A suspended plasterboard ceiling does not carry on its own and needs its own substructure. With an old timber ceiling, we settle the fixing with the structural engineer. Where the ceiling is not suitable, the load can often be diverted through the wall or a separate frame.

A recessed track looks calmest, but it presupposes that the ceiling is being opened up or rebuilt anyway. Think of later years too: rollers and carriages will need servicing at some point, and they must then be reachable without chiselling.

At floor level, a small guide that holds the leaf sideways is enough for many systems. That saves the threshold and benefits everyone who wants to live without a trip edge, as the article on age-friendly living shows. If the flooring is also to run through, this spot must be agreed early with the planning of a continuous floor. What you see, though, is the glass and the profile.

Choosing glass, profile and handle

The type of glass determines what gets through. Clear glass lets light and views pass. Satin glass lets the light through and takes the view away; tinted glass lies in between and looks different depending on the time of day. For doors, safety glass is standard: toughened glass breaks into small crumbs, while with laminated glass a film holds the shards together. What is required for a specific installation, we check before ordering.

The profile decides the line in the room. Slim, dark profiles draw the surface as if with a pencil, light ones recede. Frameless glass looks lightest but leaves less room for seals. You will find more on how these materials work together in the article on glass and metal in the interior.

In our example the choice falls on lightly tinted glass with a dark profile, because it looks warm beside an oiled oak floor. For nights with guests, a curtain is added on the room side.

Imagine the evening. The leaf slides open with the faintest hiss, the study lamp goes off, and the room melts back into the living space. In the lightly tinted glass the oak floor glows warm.

The handle is often thought of last and yet used daily. A flat recessed pull looks calm, but it is harder to operate with full hands or reduced strength. Try on the sample how much force the leaf needs to start moving and how it comes to rest. And what about sound and light, the two sides of a glass wall?

Acoustics and light: the two sides of a glass wall

In acoustics, the weakest point counts. A sliding door in front of the wall does not sit in a rebate, so a gap remains all round, and sound comes through that gap. Thicker glass or laminated glass with an acoustic interlayer only really helps if seals and a stop also make this gap smaller. For a video call this is enough in many cases; for two simultaneous phone calls side by side it often is not.

Test it beforehand if you can, and tell us honestly how loud things get in your home. A living space with a lot of reverberation also carries sound further. What helps against that is explained in the article on acoustics in open-plan living. How working and living get along on the same floor area is shown in the article on the home office in the apartment.

For light, a simple rule applies: glass turns into a mirror on the brighter side as soon as it is dark behind it. In the evening, from the lit living room you then no longer see into the next room but only yourself. Some light on both sides keeps the surface translucent. How lighting joins or separates zones is described in the article Light as a transition. Vienna's Altbau adds questions of its own.

Altbau and the private zone: special questions

Vienna's Altbau apartments (the pre-1945 apartment buildings) often take floor-to-ceiling glass very well, because the rooms are tall and the walls strong. On the other hand, floors and ceilings are rarely parallel, and behind the stucco there is frequently a timber ceiling. A system has to absorb such deviations without the leaf rolling off on its own or the joint at the top looking crooked. Where an existing hinged door is part of the apartment's character, we first check whether it would not be better to keep it.

If a wall is altered for a larger opening, structure and permits come into play. The basics are in the article on removing load-bearing walls in Vienna. If an element borders the stairwell or an escape route, separate fire-safety requirements also apply, and we clarify them in advance.

Glass elements work particularly well in the private zone between bedroom, dressing room and bathroom. Satin glass brings daylight from the bathroom into the bedroom and still protects against views. However, a sliding door contains moisture and noise less well than a door with a rebate, so the bathroom ventilation must work independently. How this sequence of rooms is planned as a whole, you can read in the article on sleeping, dressing, bathing. How do you tell a good system from one that merely looks good?

Judging quality and putting costs in context

In a brochure many systems look the same; the difference shows in use. At the sampling stage, look out for these points:

• Running noise: The leaf glides evenly and quietly, right at the start and at the end of its travel.
• Damping: A soft-close damper slows the leaf gently and draws it into its end position.
• Gaps: The joints to wall, ceiling and floor are even and can be readjusted.
• Surfaces: Profiles meet exactly, the glass edges are cleanly finished.
• Cleaning: You can reach both sides of the glass, even when open and even in the pocket.
• Service: Carriages are accessible without building work, and spare parts are available later too.

What the article on quality beyond the name describes applies in general: the verdict falls on the detail that you can check yourself.

The costs depend on the system type, on the size and weight of the leaves, on the type of glass and the profile, and also on the installation situation. A wall pocket or a new ceiling construction weighs more heavily than mounting in front of a load-bearing wall. Added to that are electrics, decorating and adjoining built-in units. A binding estimate is given at the first meeting. Sometimes a good sliding door saves an expensive conversion; sometimes a simpler solution is enough, and the budget is better spent in the kitchen or bathroom. We plan glass, ceiling and surrounding joinery as one, with one person responsible from the first sketch to handover.