"Toilets do not look like that"

A five-year-old was looking over my shoulder at a floor plan on a screen. She pointed at a small rounded rectangle with a smaller rounded rectangle stuck to the end of it and asked what it was.

"A toilet," I said.

"That's not what toilets look like."

She was right, from where she stands. She's used to seeing things from the side, and a floor plan shows everything from straight above. The sink, the bathtub and the stairs are the same: almost nothing on a floor plan looks like the thing it's supposed to be.

And once you know why, the whole page opens up.

A floor plan symbol isn't a realistic picture of an object. It's closer to a word for that object.

Think about how the word "toilet" works. Seven letters, no resemblance to porcelain whatsoever, and yet everyone reading this understood it instantly. It works because we all agreed it means that, not because it looks like it.

Plan symbols work exactly the same way. Architects agreed, a very long time ago, that this shape means toilet, and now anyone in the world can pick up a drawing and read it without a key.

Symbols look the way they do for three reasons.

They are a view from above. You are used to seeing a toilet from the side. A plan looks straight down at a building that has been sliced open, so a toilet shows up as a rounded bowl with a rectangle behind it. Same toilet, different angle.

They are simple. A whole house has to fit on one page, so every fixture is drawn small, and a plain outline stays easy to read where a detailed drawing would blur.

They are the same every time. A symbol only works if everyone draws it the same way, so anyone can pick up a plan and read it.

The ones worth knowing

Once you accept that they're words, they're easy to learn. These few cover most of what you'll see:

• 
  Door: a gap in the wall, a straight line, and a thin quarter-circle arc.
• 
  Window: a gap in the wall crossed by thin lines. Thinner than the wall, because you're looking at sliced glass.
• 
  Stairs: a run of parallel lines like a ladder, with an arrow. The arrow means "up". Stairs are the one symbol that tells you which direction it's pointing, because a plan can't show you height.
• 
  Toilet: oval, plus a rectangle for the tank.
• 
  Sink: a rectangle with a circle or oval in it, usually with a small circle for the faucet.
• 
  Bathtub: a big rounded rectangle with the drain marked at one end. The drain end tells you which end the faucet is on.
• 
  Refrigerator: a rectangle, often just labeled REF, because a fridge from above is a rectangle and there's nothing more to say.

Notice how much information is hiding in those. The tub tells you which end you sit at. The stairs tell you which way is up. The door tells you where you can't put furniture. None of them look like the thing, and all of them tell you more than a picture would.

Follow along in the Designer, one step at a time

Open Tiny Architects Designer. This lesson has a trick to it: the app can show you the symbol and the real object, which a piece of paper can't.

1. Draw a small roomWalls › Outside › House Outline👆 Show me

   Small, bathroom-sized. About 8 feet by 6.

2. Fill it with fixtures, without looking at the namesBathroom › Fixtures👆 Show me

   Drop in a Toilet, a Vanity, and a Bathtub or a Shower. Put them where they'd really go: fixtures go against walls, because that's where the pipes are.

3. Zoom out, then back in

   Zoom out until the room is small on your screen. That is the important part: at that size every fixture stops being a shape and becomes a symbol, and it is the size a real plan gets read at.

   Now zoom back in and look properly at each one. The toilet really is an oval and a box. The tub really is a rounded rectangle with a drain at one end. You've just read a plan.

4. Add a door and a windowDoors › Single DoorWindows › Single Window👆 Show me

   Find the difference. The door has an arc. The window has thin lines and no arc. Two holes in a wall, and the symbol tells you which is which without a single word.

5. The payoff: flip to 3DPlan → 3D👆 Show me

   Every symbol turns into the actual object.

   Flip back to Plan. Then to 3D again. That's the translation that takes architects years to build in their heads, and you just did it with a button. Every oval-and-a-box on every plan you ever see from now on is going to be a toilet, automatically, without you having to think about it.

   ---

Now make your own, using what you just learned

Make a symbol quiz for someone else.

1. Draw a room (a bathroom or a kitchen) with four or five fixtures in it.
2. Take a screenshot in Plan view. No labels, no 3D.
3. Show it to a grown-up and ask them to name every symbol.

Two things happen, and both are interesting. Grown-ups get more of them right than they expect, because they've absorbed these shapes from a lifetime of house listings and IKEA catalogs without ever being taught them. And the ones they get wrong are almost always the same ones: the shower, usually, because a shower from above is just a square.

Then flip to 3D and show them the answers.