Proposal:Allow area=yes for indoor=wall

Allow area=yes for indoor=wall
Proposal status:	Proposed (under way)
Proposed by:	CommanderStorm
Draft started:	2025-10-29
RFC start:	2025-12-03

Problem Statement

A wall is a non-walkable concrete/paper/clay/.. barrier between rooms.

Currently, the state of the tagging is that

• indoor=room have implicit walls
• indoor=area does not have implicit walls
• indoor=corridor are walkable and don't say something about walls
• indoor=wall is a non-walkable barrier
• indoor=door can allow passing through indoor=wall and the implied walls

This works reasonably well for newer buildings with thinner or uniformly thick walls.

The scheme falls apart for older buildings with non-uniform walls. Currently, the guidance is to “just” simplify the wall down to its middle line. This works for thin or uniformly thin walls, but creates ugly artefacts in older buildings.

This issue is not limited to old buildings.

example of how this affects buildings

TU cheminz university library with walls of varying thickness, mapped as room outlines instead of wall middle lines.See location In indoor= or in osminedit

Example floor plan that is unclear in how it can be mapped due to non-uniform thick walls: Should wall of the room on the top-right have an indentation to follow the middle of the wall or stick with the outside wall?

A newer building showing how naively mapping the centre of the wall in some cases changes either the building outlines, the inner geometry or both. See location in indoor=

Proposal

Allow mapping walls as areas tagged with indoor=wall + area=yes.

Rationale

Our problem solves the problem statement by allowing users to create “weird” non-uniform walls and thick wall segments.

rejected alternatives

idea	considered because	rejected because
using indoor=column	collums can be mapped as indoor=area. Technically, using them to map walls is thus possible.	Very counter-intuitive. Collumns are not usually considered like this.
introducing indoor=opening	Simpler for 3D rendering	Breaking change for indoor rendering, indoor routing, tactile indoor maps and forces all of these users to do complexer 3D boolean math. I also consider this harder to reson about and enabling simple mistakes like not fully open openings in a wall makes editing harder. The counter-proposal was discussed here.
Adding indoor=opening just for windows	Simpler for 3D rendering	Feedback from the 3D rendering community is that tagging windows as nodes and not having openings is simpler. This also makes editing harder due to more overlapping things.
indoor=door inside walls without connections	This was one of the options discussed in https://kartdok.staatsbibliothek-berlin.de/receive/kartdok_mods_00001059	Harder to reson about for taggers due to editor support and data consumers. Non standard to how other items on the map are usually connected to others.

Tagging

The proposal proposes to allow the tag combination area=yes + indoor=wall.

This makes it consistent with what is allowed for indoor=column

Walls can be mapped as such:

The tag indoor=wall is used to map non-passable indoor wall elements.

Note that this tag should only be used if the wall is not already defined by indoor=room or if the wall's geometry requires area-based mapping.

Draw a way along the wall's location. This tag may be used either as:

• a way or as a closed way (without an area tag). Tag the way with indoor=wall and level
• an area along the non-walkable area. Tag the closed way with indoor=wall, level and area=yes.

Due to being simpler to tag and due to better support for tactile maps (“3d-printed maps for blind people”), a way or as a closed way (without an area tag) is preferred if walls are uniform in thickness.

Examples

Here are items that are better tagged as area=yes + indoor=wall

tagging	real world situation
Two rooms with irregular walls being connected via a door
The door can also be in the middle and not on one side	Seems exceptionally rare in reality. No example found.
Wall being in a room, but not on the outside

Here are related examples:

tagging	real world example
already existing based indoor=column
already existing based indoor=column

Impact on Data Consumers

These consumers of the data exist, and this is the impact for them:

usecase	impact	rationale
2d rendering "floor-plans"	no impact	For better display these can now be filled with a solid color.
tactile floor plans	limited impact	Walls are usually printed as small ridges. Having ridghes on both side of the wall is not ideal. If printed on a common 3D printer are one slightly thicker line, so likely no impact. Better preprocessing can buffer-without-overlap these into a line geometry. The "lumpy" case noted above does not change with this processing,
3d rendering	yes	Walls should be rendered as slightly extruded 2d lines. For windows/doors, one currently remove walls when a window/door is present If walls are areas, these areas need special handling
indoor navigation	no impact	walls are non-routable before and are this after the proposal
"Typical" outdoor renderers/ navigation	no impact	All known renderes ignore indoor=wall

Features/Pages affected

To describe that walls can be areas, with some example pictures and diagrams.

• Tag:indoor=wall
• Simple Indoor Tagging

A cross-reference to Tag:indoor=wall on the following pages is intended:

• Tag:indoor=room
• Tag:indoor=corridor

A cross-reference on Tag:indoor=wall that Tag:indoor=column exists

External discussions

To gather feedback before writing a proper proposal: https://community.openstreetmap.org/t/allowing-area-yes-for-indoor-wall/137010/26

Comments

Please comment on the discussion page.