Guides · Balcony · 12 min read · Updated September 2026

The balcony

The only outdoor room most people have, and the one the classical manuals never wrote a chapter on. What the veranda and the five-foot way of the old houses were for, the depth below which a balcony is a shelf and not a room, the rail read as a wall and the void read as the missing tortoise, how much of the view to keep and how much to plant out, and the question every balcony eventually faces, which is whether to glaze it in.

Oriented SE 135°

Wood

Fig. 01 A balcony with a table and chairs on it, seen from the doorway. A balcony deep enough to hold a chair and let someone pass behind it is used; one that is not deep enough becomes a shelf, which is a finding of the design literature and not of the manuals.

A flat has one piece of outdoors and it is usually three or four square metres of it. The classical manuals have nothing headed balcony, because the buildings they were written for did not have one; what they have instead is the veranda that ran along the front of a southern house, the arcade the Straits shophouses shared, and the sky-well cut through the middle of a courtyard house, all of them places that were neither the room nor the street. This guide reads a balcony as the last of that line. It gives the depth below which a balcony is a shelf rather than a room, which is a finding of the design literature and a good one; the rail as the garden’s wall and the void as the problem behind the chair; how much of the view is worth keeping; and the question every balcony in Europe eventually faces, which is whether to glaze it in.

The outdoor room the tradition already had

The southern Chinese house put a covered walk along its front, open to the court and roofed by the eaves, and Knapp’s surveys record it in house after house as the place where the household actually sat: shaded at noon, dry in the rain, and neither inside nor out. The Straits shophouse turned the same thing into public property with the five-foot way, the arcade Raffles’s town plan required in 1822, which the shophouse essay gives in plan. And the courtyard house cut the sky-well through its middle, an unroofed opening the width of the lot with a drain in its floor, which the houses essay describes and which brought the weather into the centre of a plan that had no side windows.

Three different buildings, one idea: a household needs a place that is covered by the house and open to the sky. A balcony is that place at the scale of a flat, and reading it as the descendant of the veranda rather than as a spare surface is most of the guide. What the manuals ask of the veranda they would ask of it: that it be reached from the room that is most used, that it be shaded when the sun is high, that something solid stand behind whoever sits on it, and that the view from it be composed rather than merely available.

Evidence · Six feet, and the balconies nobody stands on

Alexander’s pattern language contains a finding worth more than most of the balcony advice ever written: balconies and porches less than about six feet — a metre eighty — deep are hardly ever used, and he says why. Below that depth there is no room for a chair to be pulled out and for somebody to pass behind it, so the space can be stood in but not occupied, and the household stops going out. Panero and Zelnik’s dimensions give the same arithmetic from the other side: a seated person at a small table takes roughly seventy-five centimetres from the table’s edge to the back of the chair, and a person edging past behind them needs another forty-five. Add the table and the numbers land where Alexander’s observation landed. This is design observation, not experiment, and the site labels it so; but it is the one measurement that decides whether a balcony is a room.

What a shallow balcony can be

1The door, from the room the household uses most
2The clearance a chair needs behind it, which a metre twenty has not got
3The seat with the flat’s own wall behind it, and the route out that turns before it
4The rail planted along its length, with one stretch left clear opposite the seat
5The one tall plant, on the side the afternoon sun comes from

Fig. 01 The same balcony at two depths Three metres forty of frontage, drawn at a metre twenty and at a metre eighty. On the left, the depth most flats were given: the pots along the rail work, the drying rack works, and the table and two chairs, ghosted, do not — the hatched band is the clearance a person needs to pass behind an occupied chair, and it runs off the edge of the balcony. What that depth can be is a windowsill at a larger scale, and treated as one it is useful. On the right, the depth at which the tradition's rules for a room start to apply: the seat stands against the flat's own wall with the view in front of it rather than the drop behind it, the table is between the seat and the rail, and there is still room to walk past. The plant a pace out from the door turns the arrival, so that the balcony is come round to rather than faced square, which is the scholar's garden's device at the smallest scale it will work at. The rail is planted along its length except for one stretch opposite the seat, which frames the one thing worth looking at and hides the rest. Nothing here is a rule of the manuals, which have no chapter on balconies; the depth is a design observation and the seat is the command position, which the site distinguishes.

A balcony of a metre twenty is not a failure, it is a different thing, and the mistake is furnishing it as though it were a room. What it does well is what a windowsill does at a larger scale: it holds plants, it dries washing out of the weather, it gives the room behind it a layer of green between the glass and the street, and it is stood on for a few minutes at a time. Treated as that, it works. Furnished with a table and two chairs it becomes a place where the chairs are permanently pushed in, which is the state most balconies in most cities are in.

A balcony of a metre eighty or more is a room, and the tradition’s rules for rooms start to apply to it. The seat wants something solid behind it, which on a balcony means the flat’s own wall and not the rail; the approach wants to bend, so that a person stepping out turns to the view rather than facing it square from the door; and the floor wants to be clear enough that the route from the door to the seat is a route. The garden essay draws exactly this in pots, with the six devices of the scholar’s garden set out on four metres by one and a half, and it is the better drawing to work from once the depth is there.

Design observation · Three square metres, and what a landscape architect does with them

The trade’s answer to a small outdoor space is not more objects but fewer and larger ones: one plant tall enough to read as a tree rather than six pots that read as a shelf, one surface at the right height rather than a table and a stool and a shelf, and the floor left clear. The reasoning is the same one the tradition gives for a room — a space is read by what it lets you do in it, and a floor is a thing you can do something with. Heisler’s and Akbari’s measurements of urban trees are about streets rather than balconies, but the mechanism they measured, that shade on a west-facing surface is worth several degrees in the afternoon, is exactly why a single tall plant on the hot side of a balcony changes the room behind it.

The rail, and what stands behind the chair

The tradition reads a seat by what is behind it, which the command position essay gives at length, and a balcony is the one place in a flat where the answer can be nothing. A chair set against the rail with its back to the drop has the void behind it, which the manuals would call the tortoise missing and which most people feel without naming: it is why the seats on a balcony end up against the house wall even when the view is better the other way. Put the seat against the flat’s own wall, facing out, and the position is the room’s rule kept exactly.

The rail itself is the garden’s wall, and its three common forms do different things. A solid rail, masonry or panel, gives real enclosure and takes light from the floor, which matters on a shallow balcony and on a low floor. A glass rail keeps the light and gives no enclosure at all, so a person sitting behind one is sitting in the open; the usual remedy is planting along its inner face rather than frosting it. A railing of bars is the old compromise and the one the planting works best with, because pots can sit on the inside edge and the wall builds itself over a season. Whichever it is, the height that matters is not the code’s but the seated one: a rail that reaches a standing person’s waist reaches a seated person’s eye, which is why a balcony can feel enclosed standing up and exposed sitting down, and why the planting goes where the seated eye is.

1The rail at a hundred and ten, which is a standing person’s waist
2The seated eye at a hundred and fifteen, five centimetres above it
3The standing eye at a hundred and sixty, well clear of it
4The planting, which puts the wall back at the height the seated eye is at

Fig. 02 The rail, and the two eye lines The rail of a balcony drawn in elevation from inside, at the three heights that decide what it does. The horizontal dashed lines are the eye heights this site uses throughout, a seated eye at a hundred and fifteen centimetres and a standing eye at a hundred and sixty; the rail is at a hundred and ten, which is roughly a standing person's waist and about where the building codes settle. Those three numbers are the whole drawing. A solid rail gives real enclosure and takes light off the floor, which tells on a shallow balcony and on a low storey. A glass rail keeps every bit of the light and gives no enclosure whatever, so that a person sitting behind one is sitting in the open; frosting it loses the light without giving back the shelter, and planting along its inner face is the usual answer. A railing of bars is the old compromise, and the one the pots work with, because they sit on the inside edge and the wall builds itself over a season. What the three have in common is where the rail top falls: five centimetres under the seated eye, which is why a balcony can feel enclosed standing up and exposed sitting down, and why the planting goes at the seated eye and not where a standing person judges it should.

How much of the view to keep

Not all of it. The Chinese garden’s device for a view is jie jing, the borrowed view: a scene outside the garden is taken into it by being framed, and everything on either side of the frame is planted out. Keswick’s account of the garden gives the device and the garden essay applies it to a balcony, and it is the right instrument for a city, where the view is one good thing and four bad ones. Leave the rail clear for one stretch, opposite the seat, and plant the rest. What that buys is a view that gets noticed rather than one that stops being looked at.

There is research about views, and it is worth being exact about what it says. Ulrich’s gall-bladder patients recovered faster with a window onto trees than onto a wall, and Kaplan and Kaplan’s work found attention restored by looking at natural scenes; neither study is about balconies and neither measures a composed view against an uncomposed one. What can be said is that a view of something living is better than a view of a wall, which is enough to justify the planting and not enough to justify anything sold with it. On the noise, Banbury and Berry’s survey of open-plan offices found overheard conversation the most disruptive sound of all and the one workers reported not getting used to. That is an office and not a balcony, and the site does not pretend otherwise; but it is the reason worth testing on your own, which is that a balcony over a pavement where people stand and talk is harder to sit on than a balcony over steady traffic, whatever the meter says about the decibels.

Glazing it in

Sooner or later somebody proposes to close the balcony with glass, and in much of Europe it is already closed. It is the biggest change a flat’s outdoor room can undergo and it is worth setting out plainly what it does. It gains a room that can be used in the cold months, a barrier against traffic noise, and somewhere to put the things that were making the balcony unusable. It loses the outdoor room entirely: an enclosed balcony is a small, hot, bright room with a door onto the living room, and the household stops going out to it in summer for the same reason they stopped going out to a metre-twenty balcony, which is that it is no longer outside. It also takes light and cross-ventilation from the room behind, since the air that used to come in through one opening now comes through two in series, and the air guide gives what that costs.

1The door between the room and the balcony, which stays in both
2Where outside begins, which is the whole of the difference
3The air, through one opening or through two in series
4The low winter sun, which reaches the same distance in and through one pane more

Fig. 03 Open, and glazed A living room of three and a half metres with a balcony of one metre eighty, cut lengthways, two sixty from floor to ceiling and the storey above roofing the balcony. Open, on the left, the boundary of the flat is the wall with the balcony door in it, the balcony is outside, and the air reaching the living room has crossed one opening. Glazed, on the right, the boundary has moved out to the rail, the balcony is a small room with a door onto another room, and the air now comes through two openings in series, which is what the air guide's figures are worth reading against. The low winter sun is drawn at the same angle in both, grazing the soffit of the balcony above and reaching about sixty centimetres past the door; glazing does not shorten it, it takes a share of it at every pane. Nothing here says do not glaze a balcony. It says what is being exchanged, which is an outdoor room for an indoor one, and that the households in the shophouse essay who roofed over their sky-wells for floor space are the ones who bought air conditioners first.

The reading the manuals would give is the one the shophouse essay records from the twentieth century: the households that roofed over their sky-wells for floor space are the ones that bought air conditioners first. The bright hall of a flat is small enough already. If the balcony is glazed, the guide’s advice is to make the glazing openable along most of its length rather than fixed, and to keep the door between it and the living room, so that what has been built is a veranda that can be shut and not a room that cannot be opened.

The tests, on the balcony

Measure the depth. Under about a metre eighty, furnish it as a windowsill and not as a room. Over it, the room’s rules apply.
Sit down. Where does the rail come to now? A rail at a standing waist is at a seated eye, and the seated eye is where the planting goes.
Turn the chair round. Does the seat have the flat’s wall behind it? A chair with the drop behind it is the one nobody chooses twice.
Step out of the door. Do you see the whole balcony at once? A plant or a screen a pace from the door turns the arrival, which is the garden’s device at the smallest scale.
Find the one view. Leave the rail clear for that stretch and plant the rest. A view left whole is a view that stops being looked at.
Look at the floor. Is there a route from the door to the seat? Everything that is not the route can be a pot; the route cannot.
Stand on the hot side at four in the afternoon. That is where the one tall plant goes, and the room behind it will feel the difference before you do.
If it is glazed, open it. Can most of the glazing be opened, and does the door to the room still close? A veranda that can be shut is worth having; a room that cannot be opened is not what was there before.