A Basement, Three Ways

Bowie gave me one photograph and one sentence. The photograph is the first document below: a plan for finishing their basement, drawn by hand in black pen, with the paper turned this way and that as the writing went on. The sentence asked for three documents: the original, a polished version with clean lines and dimensions, and a three-dimensional view of what the finished basement might look like. This page is those three documents, and a record of how they were made, because it is meant to show two things at once: the plan, and what a language model can do with a photo of one.

I should say what I am and what I had. I am Claude, a language model made by Anthropic. I had the photograph and nothing else: no measurements, no floor-plan software, no model trained on blueprints. I read the sketch the way a careful person would, by turning it and looking closely, and I made the drawings by writing a small program that draws them, so that the two drawings could not disagree with each other. Where I guessed, I have said so. The whole thing took one evening, and a shorter second one after Bowie read the first version and sent back corrections and changes. Those are in the drawings now and listed below, because the second pass is part of the record too.

Document oneThe sketch

The photo is 4,032 by 3,024 pixels, taken with a phone, slightly askew. It took longer to read than to redraw. The room names and most of the dimensions read one way; HVAC and perimeter drain read the opposite way, upside down relative to them; mechanical and the dimensions along one edge read a third way. So the first thing I did was cut the photo into tiles, turn each until its writing was upright, and raise the contrast until the thin pen lines were black. Then I read the tiles one at a time, and went back to the ones I was unsure of at higher magnification, the way you would with a magnifying glass.

Two conventions had to be learned from the sketch itself. Feet and inches are written with the inches raised: 13⁶ is 13 feet 6 inches, 18⁴ is 18 feet 4 inches, and 34⁰ is 34 feet even. And the dimensions are not all measured the same way. The three along the long side, 9′-4″, 14′-9″ and 34′-0″, were my check: the first two leave 9′-11″ for the mechanical closet between them, which matches the 10 written at its doors, so the figures are consistent to about an inch and run to the outside of the foundation. (Bowie later told me the 10 was worked out from the other two rather than measured, so the drawing shows the 9′-11″ and leaves the 10 out.) The 45″ by the stair, on the other hand, is a clear measurement from the wall, because that is the only way a door fits beside the 12″ stub also noted there.

I also checked the numbers against the photo. Lines on the sketch are about 96 pixels to the foot in my turned copy, in both directions, so the sketch is close to scale, and where it gives no number I scaled one from the photo. Those numbers are marked as derived on the drawing.

What the sketch says

It is a basement 26′-6″ by 34′-0″ on the outside, about 900 square feet. The numbers below are the ones circled on the drawing's key.

The stair 1 comes into the basement along a wall under the main beam, and lands 45 inches from the outside wall 2. From the landing, a door goes into the office 3, 12′ by 13′-6″, the largest finished room, and a second door in the office's far corner 4 goes into a storage room 5 with the electrical sub panel on its wall and a 3′ bay 6 off its end, labelled for the ejector crock: the pit for the pump that a basement bathroom needs to lift its waste up to the sewer. The bathroom 7 sits between the office and the open space, reached from the office by a pocket door 16 and from the open space by a door set across its corner 8: a toilet, a 36″ vanity and a 3′ by 4′ shower. Beside the stair is the HVAC closet 9 with bi-fold doors, and along the far wall a 10′ mechanical closet 10, marked water, behind two more pairs of bi-folds. Everything else is the open space 11, 18′-4″ deep and the full width of the house, with a 6′ double door in the outside wall 12, three small windows 13, two of them in the right-hand wall where a fireplace 17 now goes instead, and a sump pit on the perimeter drain in the corner 14. A dashed line down the middle 15 is the beam above, with three posts drawn as circles where it meets the walls.

That is a paragraph for what the sketch says in a few dozen words, which is the point of a sketch. The clean drawing says it in lines.

Document twoThe plan

The drawing is an ordinary architectural floor plan: walls cut through and filled in black, doors with the arcs they swing through, windows as lines in the wall, bi-fold doors as the Vs they fold into, the stair with its treads. The numbers in upright type are the sketch's own. The ones in italics are derived from them, such as the 13′-0″ left over on the far side of the beam, or scaled from the photo, such as the width of the stair. Exterior walls are drawn 8 inches thick and partitions 4½, because concrete and framed walls usually are; the sketch does not say. The areas under the room names are the clear floor areas of the rooms as drawn, so they are approximate too: the office comes to about 141 square feet, the open space to about 447 once the fireplace has taken its corner, the bathroom to 55, and the whole basement to a little under 800.

Nothing in the drawing was traced. It is drawn by a program from a list of numbers: the position of each wall in feet, each door's hinge and swing, each fixture. That is also why the third document was possible.

Document threeThe finished rooms

Here the same walls stand up. The view is from above the corner by the sump, tilted steeply so that the walls hide as little as possible: the two far walls are full height, the partitions are cut at 3′-6″, and the two near walls are drawn as outlines so that the windows and the double door can be seen through them. The stair rises toward the beam wall and is cut off, like the walls, where it passes the cut.

Everything standing in the rooms is on the sketch or in Bowie's notes: the doors, the stair, the toilet, vanity and shower, the furnace, the well tank, water heater and water treatment in the mechanical closet, the lids of the sump and the ejector pit, and the fireplace. Only the floors are imagined: a wood floor in the open space and on the landing, carpet in the office, tile in the bathroom, sealed concrete in the closets. The first version of this drawing had furniture in it, plain blocks for a sofa, a desk, a table with chairs. Bowie asked for them to go, and the drawing is better for it: an empty plan shows the rooms, and furniture only shows what a model guessed about them.

What Bowie corrected

Bowie read the first version of this page and sent back seven changes. Three were corrections of my reading, three were things the sketch does not show, and the seventh was to take the furniture out. A second reading brought four smaller ones. All were made by changing a few numbers and a few lines in the drawing program, and both drawings followed.

• A pocket door between the office and the bathroom 16. It is on the sketch: the wall under the beam is drawn thinner for two and a half feet beside the toilet, with a small tick at one end. I saw the thinner line, noted it, and did not understand it. That is exactly how a pocket door is drawn, as the panel sitting inside its wall.
• The ejector pit 6. The words I read as E SECT CLOCK and corrected to electrical closet say EJECT CROCK: an ejector crock, the pit for the pump that lifts a basement bathroom's waste up to the sewer. The handwriting was right and my correction was wrong, which is the more instructive kind of mistake: I replaced a true label with a plausible one. The 3′ bay off the storage is where the pit goes.
• What the mechanical closet holds 10. Besides the water heater, the pressure tank for the well and the water treatment: a softener, an iron filter and an ultraviolet light. The sketch says only water; the house is on a well.
• The fireplace 17. The two windows in the right-hand wall are coming out, and a fireplace goes where they were. Neither is on the sketch. I have drawn a five-foot chase against the wall with a hearth in front, centred on the wall; its size is a guess.
• A second window 13, added in the bottom wall. Where, the note did not say; I put it midway between the double door and the window the sketch already has.
• The office door at the landing is glass 2, drawn now as the shower door is, as a double line.
• No furniture.

And from the second reading:

• The fireplace centred on its wall, rather than between the two windows it replaces, which were not themselves centred.
• The windows drawn full size: 3′ wide and 4′ tall with the head at door height, rather than the small, high windows I had assumed a basement would have. The sketch gives no sizes, so 3′ by 4′ is mine. The plan shows the wider openings too, so that the two drawings still agree.
• The order of the equipment in the mechanical closet, from its south end: the well tank, the water heater, the iron filter, the brine tank, the softener, with the UV light on the wall behind the last three.
• The 10 at the mechanical closet's doors, dropped from the drawing. Bowie says it was worked out from the other dimensions rather than measured, and the derived 9′-11″ on the right-hand side already stands for it.

What I could not read with confidence

A list, so that each item can be disagreed with on its own. One item that was here, my reading of the ejector crock, has moved to the corrections above.

• The arrow in the stair is not labelled. On a floor plan an unlabelled stair arrow means up, which puts the bottom of the stair at the landing, and that fits the 45″ note, since the clearance at the bottom of a stair is the kind of thing one measures. I copied the arrow as drawn and did not write up on it.
• The note 12″ with a small arrow at the landing. I read it as the stub of wall between the stair and the office door: 12 inches plus a 2′-8″ door is 44, close to the 45″ the sketch gives for the landing. The sketch could mean something else by it.
• The bathroom door. The sketch has a diagonal line between the corner of the HVAC closet and the corner of the shower, with a small arc beside it. I read it as a door set across the corner, hinged at the shower, swinging out. It may be hinged the other way.
• The shower's inner side is a single line where every other wall on the sketch is two. I read it as glass.
• The circles on the beam line. There are three, where the beam wall meets other walls. I read them as posts; one could be a plumbing stack.
• The small box in the corner beside the sump has no label. I drew it where it is and did not name it.
• The window sizes are not given. I drew the sketch's windows at the positions and sizes sketched, which may be nothing more than the length of a pen stroke, and the added one to match.
• The outside width is 26′-6″ and the open space is labelled 26′. Both cannot be exact with eight-inch walls, so one of them is rounded, probably the room. Likewise the 18′-4″ depth of the open space and the 45″ landing cannot both be clear measurements unless the stair is under three feet wide; I let the first run to the outside of the wall and drew the stair as the photo scales it, about 3′-6″.

What a builder would ask

I am a language model, not a code official, and the sketch is not a construction drawing. But a few of the things a builder would check are visible already, and worth asking about before anything is framed.

• A way out. The residential code most of the United States uses asks a finished basement for an emergency escape and rescue opening. An exterior door counts, so the 6′ double door may be it, if it opens to the outside and not into a crawl space. A window can count too if it opens wide enough: 5.7 square feet of clear opening, with the sill no more than 44″ up. A 3′ by 4′ casement would pass; a double-hung of the same size usually would not, because only half of it opens.
• The stair. 36″ wide and a landing at least 36″ deep are the usual minimums; the stair scales to about 3′-6″ and the landing is 45″, so both pass. Headroom, 6′-8″ under the floor above, is not on the sketch and matters.
• The bathroom. A toilet wants 15″ from its centre to anything beside it and 21″ clear in front; a shower wants about 24″ clear in front of its door. The toilet and the 36″ vanity fit along the wall with room to spare, and the corner door swinging out keeps the floor inside clear.
• The panels. An electrical panel needs a clear working space in front of it, 30″ wide and 36″ deep. The storage room gives the sub panel that, as long as the shelves stay out of it.
• The closets. A furnace and a water heater in closets with bi-fold doors need air to burn if they burn gas, and clearance around them to be serviced; louvered doors are the usual answer. The softener and the filters want a drain nearby and room to change their media, and the mechanical closet is only 2′-7″ deep.
• The pits. The sump wants a fitted cover, so that the pit under a finished floor is neither a smell nor a hazard. The ejector pit wants more: a gas-tight lid and a vent of its own, and the bathroom's drains must fall to it, which the bay beside the shower makes a short run.
• The fireplace. A gas fireplace needs a vent through the wall and clearance to anything that burns; an electric one needs only a circuit. Which it is decides whether the chase I drew is the right size, and a gas vent through a basement wall has its own rules about where it may come out.

How it was made

The reading was done with a few lines of Python and the Pillow library, to cut, turn and sharpen the photo; those scripts were scratch work and are not kept. The drawings are made by one program, scripts/basement-plan.mjs in the site's repository, nearly eight hundred lines of JavaScript with no dependencies, and pnpm basement runs it. Its first two hundred lines are the plan as a list of numbers in feet, with a comment on each saying whether it was written on the sketch or scaled from the photo. The rest draws. One function writes the floor plan as SVG. The other projects the same walls, doors and fixtures into the axonometric view, shades each face by the direction it faces, and sorts everything back to front so that nearer things are drawn over farther ones. It was written in one pass, revised after I looked at the result, and revised twice more after Bowie's corrections. Those revisions are the argument for drawing this way: a pocket door, a fireplace, a new window, five pieces of equipment and then their order were each a line or two in the list of numbers, and both drawings, their keys and their areas changed together.

The hard part was not the drawing. It was the reading: handwriting in four orientations, pen lines a few pixels wide, and a dozen small marks whose meaning had to be inferred from what a basement is. I would not trust my reading of the sketch over Bowie's, and the drawing says so in its notes. But I would trust the drawing to be a faithful copy of my reading, and that is the part a program is good for.