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The story
A floor-plan simulation image for a self-designed dream house, posted to 5ch’s News VIP board, became a hot topic. Users well-versed in real-world home-building specifics chimed in one after another with pointers on everything from roofing material choices to bathroom placement and hallway width. At one point, someone even quipped, “The simulation police are here.”
What people said
Also wouldn't recommend metal roofing material.
The exterior wall material's just a placeholder.
I'm leaning toward galvalume (galvanized steel siding), though.
Why's a mono-pitch roof a bad idea?
Sorry.
Sorry about mine too, I guess.
Those are the height of stupidity.
Wasn't planning to add them, but honestly the simulator didn't even have that option to begin with, lol
Re: #12
That's a spot for a motorcycle.
The car goes outside the house, I guess.
A windowless bathroom is a common layout in apartments, but since this is a single-story house, might as well take advantage of it.
Don't sweat the small stuff, the controls are hard to use.
Re: #17
Yeah, a window in the bathroom would be nice.
That's good input, thanks.
That's way too much, lol
Why's there 4 chairs at the living room table then?
If I were building a 4LDK (4 bedrooms plus living/dining/kitchen) within 30 tsubo (~99 m²), I'd go with something like this:
So you have to walk through the washroom and changing room to get to the Western-style room?
Having the kid's room (presumably) right past the changing room sounds like a nightmare, honestly.
I have no idea what you were going for with this layout.
Looks like something an AI spat out.
The hallway narrowing down isn't great.
I did make sure to keep it at 910mm (standard Japanese building module width), for what it's worth.
910mm is measured center-to-center between walls, so you need to picture the actual walkway as about 100mm narrower than that.
ID:fXVxrfAI0 is a solar-panel zealot who's always starting threads like this on VIP, best not to engage.
There's "not knowing" and then there's this — way beyond the pale.
Wait, if you go in next to the entrance here, aren't you boxed in by walls on 3 sides?
Where do you even get into the room from?
Should be obvious if you think about it normally.
That's just the threshold between the doma (earthen entry floor) and the kamachi (raised step) — it only looks like a wall.
Oh, that's the kamachi?
I thought it was a wall.
Seems like the AC wouldn't cool it well.
I actually work in equipment installation, so I'm planning to put in a packaged air conditioner!
Though nothing's actually decided about building it yet.
If the LDK (living/dining/kitchen) is 33 square meters, that's under 20 tatami mats, so a regular AC should handle it fine.
Sounds like the L-shape is a deliberate choice, so I guess that's fine.
Though the bathroom being dead center does bug me a bit…
And taking out the food waste means walking all the way around to the front door. That's unreal.
Isn't that pretty normal, though?
How much do you hate walking, seriously…
Background and Key Points
Japanese house listings and forum sketches like this one are built on a specific vocabulary outsiders won’t recognize. “4LDK” means four bedrooms plus a shared Living-Dining-Kitchen, and “30 tsubo” is a build size (1 tsubo ≈ 3.3m², so roughly 99m² total) — both are standard shorthand on Japanese real-estate and architecture sites. Home layouts here are also typically drawn on a 910mm structural grid (inherited from traditional shaku/ken measurements), which is why posters treat “I kept it at 910mm” as meaningful discipline rather than an arbitrary number.
The thread’s actual fault line wasn’t “good design vs. bad design” — it was over how harshly to police an admitted amateur’s hobby simulation. Some posters piled on with genuine construction expertise (roof pitch drainage problems, why galvalume siding is now standard over older metal roofing, AC load per square meter), while others pushed back that dogpiling technical corrections on a self-described non-professional (“the simulation police are here”) was overkill. A secondary, quieter disagreement was whether the second poster’s more “proper” 4LDK redesign was actually better or just AI-generated-looking clutter with its own walk-through-the-changing-room flaws.
What foreign readers will likely miss: the 910mm grid measurement is center-to-center between wall studs, not the clear walking width — actual hallway space ends up roughly 100mm narrower, a well-known gotcha in Japanese home design that one poster had to explain to the thread itself. Also worth knowing: the swipe at solar panels isn’t an anti-green stance so much as a very Japan-specific one — feed-in tariff rates have fallen sharply since the program’s 2012 peak, so panels are now widely viewed here as a poor investment rather than an environmental statement.
*This article is compiled from excerpts and a summary of the 5ch (News VIP) thread “[Image] I simulated the kind of house I’d like, take a look.”
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