These duplexes are typically purpose built, and can be identified by the existence of two front doors, with one front door leading directly into one unit, and the other door opening into a staircase leading to the upstairs unit.
The wiki seems to indicate that duplexes are tagged with building=semidetached_house, but this tag appears to refer to the British definition of duplex, meaning two households with a shared wall (as opposed to a shared floor/cieling in this case). The tag building=house also seems to not be a perfect fit, as it is defined in the wiki as “structures built for inhabitation by a single household”. Thus it seems that building=apartments is the only tag that fits, although it seems to me that 2 units is a bit small to call something an apartment building.
It is definitely not a semi-detached - that’s for houses that are attached side-by-side, not top-and-bottom.
If you are sure that they are originally built with two units, I would use house or if you don’t feel comfortable calling it a house then I guess apartments. If it might have initially been built as a single dwelling and then was retrofitted to have two, I would tag detached (building tag is the originally built and still recognizable form).
I use building=semidetached_house for two houses sharing a wall and building=apartments for residential buildings incorporating at least 3 flats of similar size.
A single house with less than 3 flats is a building=house for me without considering, if it incorporates
or if it has been built as a single family house and lateron been divided into 2 separated flats or vice versa.
In my opinion this is a reasonable approach because it is difficult to draw conclusions about the interior layout from an external look at a building of such avarage size.
Anyhow in the given case it is surely legitimate as well to map these houses as apartment buildings with 2 flats if you prefer to do so.
Do they have their own garden at the back? Even if they are very close together, for me that would be building=detached. But it also depends a lot on how other mappers in the area approach it.
building=apartments because there are more than 1 residential units so that’s the only value that fits. However I don’t feel good about it and would support the introduction of a new value in the building space for such residential buildings with 2-3 units/building. In (Eastern) Europe it is quite common to first build a house for yourself, and then add floors on top for your children to live in (so they can take care of you when you’re getting older).
I wonder what we would call it - something about “multi-family”? “multi-unit”? “small multi-unit” to distinguish from apartments?
“multi-family” and “multi-unit” are descriptions I read for the expression of this idea in Toronto (“Toronto special”: 1, 2, 3) but they feel pretty generic.
Looks like Montreal triplexes (perhaps “Plateau triplexes”) are also an expression of the same idea: sample picture, another picture
“Semi-detached homes” were not an appellation we used out west until maybe 20-25 years ago. A building with side-by-side “semi-detached” homes was simply: a duplex. And so too were ones where one was top of the other; that style was much more prevalent from the 1950s until about the year 2000. If we had to distinguish between the two layouts they were “side-by-side duplexes” and “up-and-down duplexes”.
Then seemingly one day real estate agents and housing developers just started calling them “semi-detached homes”. There was admittedly a bit of a stigma that “duplexes are for poor people”; “semi-detached homes” were more respectable, I guess. (In much the same way cookie-cutter ‘McMansions’ less than 10 feet from each other in suburban culs-de-sac became “estate homes”, somehow…)
building=duplex or building=house, house=duplex seems apt to me. Likewise for triplexes and four/quadplexes.
I can see why some might prefer apartments but it seems inappropriate to me. I consider apartments to be multi-unit buildings with a common entrance, and each apartment’s access is through a common interior corridor that in itself isn’t publicly accessible. In essence it’s the same way I would distinguish a hotel from a motel: the former has an internal corridor to access each room, whereas at the latter each room is accessed directly from an outside door, typically facing a parking lot. I don’t doubt that the vernacular architecture in warmer climes might do away with the interior corridors, but that’s the most distinguishing feature here.
I don’t think it makes much sense to go for another set of building tags with no additional value like building=triplex/quadruplex/quintuplex and so on additionally to the lot we do have already.
If someone prefers “duplex” instead of “semi-detached” that’s fine. There are
7000 building=duplex
2000 house=duplex
already, just make your choice. The disadvantage of “duplex” is that one cannot know if it’s a “side-by-side” or an “one-above-another” construction, but does that make a difference? It’s a house with 2 flats anyhow.
Some confusion starts when someone draws 2 building outlines side by side and tags both of them as building=duplex. Does that mean each outline represents a single-flat-house and together it’s a duplex or are this 2 “one-above-another-duplexes” side by side?
If you don’t like “duplex”, go for building=semidetached_house (1.6 mio uses) or house=semi-detached (300K uses).
I’d say we do not need more sophisticated tags for 1-2 family homes, we do have way too many already.
Any building incorporating 3 flats or apartments is a multi-family home and we do have building=apartments for that. It does not make any difference imo if the flats are accessible by an internal corridor or via an external staircase leading to doors accessible from outside or any other way of access. Creating additional tags to distinguish the kind of access to the flats would not bring more clarity but more confusion.
A “maisonette” is an apartment spreading over 2 floors, nothing more than that. A maisonette does not require a separate entrance as described in the wiki and a separate entrance into an upper floor flat does not make the flat it a maisonette either.
Having said that I have no idea what house=maisonette is standing for. An apartment spreading over 2 floors inside a residential building is not a “house” and tagging such an apartment as house=maisonette inside a building=apartments does not make any sense to me.
Btw: The sample pic on the wiki page of house=maisonette shows a “one-above-another” duplex house as described in the OP. This is something quite different from a maisonette apartement.
I fully agree, it makes a big difference for owners and inhabitants, but does it make a real difference in OSM? It’s a 2 family home, and we neither care about noise problems nor do we map cadastral land parcels (at least until now).
Well, at least it offers the option for further specification by
We do map entirely separate addresses where we can though. Or at least I do.
I’m honestly trying to remember what I’ve done for these sorts of buildings in the past, and I’ve probably just tagged them building=apartments, building:flats=2 for lack of something else that seemed ‘better’. I can see why one might just do that and not get particularly concerned about it; I’m sure I’ve done it.
However, “does it make a real difference in OSM”? I can foresee situations where data users would want to distinguish between the building types; making a map of my city wherein “apartment buildings” were to be highlighted, but it pulls all these little up-and-down duplexes? That would seem silly. Arguably not our problem, I know, just trying to foresee where it could be…
I think of this discussion and contrast it with the “Use of building=villa?” discussion you started, wherein… I honestly have no idea why anyone would tag a house as building=villa, I don’t understand what distinguishes a villa from any other house. Here it’s just marketing clap-trap that signifies nothing other than a seller wants a lot of money for a house. “Villas” are often in the names of townhouse-condominium developments here. It seems a pointless and silly tag, to me, but it obviously means something to other people!
Can you come up with characteristics of the Altbau which make it a separate building that don’t also apply to the semi-detached?
The Altbau and its neighbours have separate addresses, separate entrances, likely separate utility connections, possibly different facade finishes, different maintenance or renovations. But so do the semis.
(For those not familiar with Berlin, this building is part of a relatively uniformly built area called Wilhelmine Ring , and basically all of it is mapped in OSM as separate ways.) ↩︎
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“Villas” are often in the names of townhouse-condominium developments here. It seems a pointless and silly tag, to me, but it obviously means something to other people!
