How to Wall


Many of you may have experienced Zerglings runby through building gaps that you think the Zerglings cannot get through. The following video explains how to wall.

I did not make the video, so credit of video goes to the owner.

Walling off technique is not exactly new, but I find this video pretty well done. The purpose of this post is simply to “transcript” the video into images and words. I find it easier to refer to images and words than videos for building placement guide.

Click to enlarge images.

Three plus two types of buildings


– 2×2
– 3×3
– 5×5
– Spore Crawler* (Spine Crawler too?)
– Vespene Geyser

Spore Crawler is a 2×2 building, but it works in a unique way. Although the video mentions only Spore Crawler as the unique 2×2 building, Liquipedia states that Spine Crawler works the same way as Spore Crawler.

Vespene Geyser (Refinery, Assimilator and Extractor) is a 3×3 building, but it also works in a unique way.

2×2 Buildings

– Supply Depot
– Missile Turret
– Sensor Tower

– Pylon
– Photon Cannon
– Dark Shrine

– Spire
– Spine Crawler
– Spore Crawler*

3×3 Buildings

– Refinery*
– Barracks
– Engineering Bay
– Bunker
– Factory
– Ghost Academy
– Armory
– Starport
– Fusion Core

– Assimilator*
– Gateway
– Forge
– Cybernetics Core
– Twilight Council
– Robotics Facility
– Stargate
– Templar Archives
– Robotics Bay
– Fleet Beacon

– Extractor*
– Spawning Pool
– Evolution Chamber
– Roach Warren
– Baneling Nest
– Hydralisk Den
– Infestation Pit
– Nydus Network
– Ultralisk Cavern

5×5 Buildings

– Command Centre

– Nexus

– Hatchery

Three sizes of units


– Marine
– Reaper
– Ghost
– Marauder
– Viking (Assault mode)

– Drone
– Zergling
– Baneling
– Hydralisk

– Probe
– Zealot
– Sentry
– Dark Templar
– High Templar


– Widow Mine
– Hellion
– Hellbat

– Roach
– Infestor
– Swarm Host

– Stalker
– Immortal
– Colossus


– Tank
– Thor

– Ultralisk

– Archon

Three types of wall

– Solid wall: No units get through
– Hard wall: Only small units get through
– Soft wall: Only small and medium units get through

2×2 and 3×3 buildings work in the same way. One adjacent square is enough to form a solid wall.


Wall diagonally will form a hard wall.


One square apart will form a soft wall.


5×5 buildings require two adjacent squares for solid wall.


One adjacent square will form a hard wall.


Wall diagonally will result in no wall off. That is, any units can get through.


Two adjacent Spore Crawlers make a hard wall. Diagonal Spore Crawlers make a soft wall.


Mineral patches form solid wall with both adjacent and diagonal wall.


Vespene Geyser forms soft wall with diagonal wall.


Top and bottom of a ramp have different wall off requirement. The image below illustrates better than words. Grey is the ramp. Top right is top of ramp and Bottom left is bottom of ramp. The red squares are not required for bottom ramp wall, but are required for top ramp wall.


Leave a comment if you know whether Spine Crawler works the same way as Spore Crawler.

EDIT: Spine crawler does not work the same way as Spore Crawler.

6 thoughts on “How to Wall

  1. Great post. I wish there was a comprehensive guide on mechanics like this, the game’s been out for 3+ years already. I wonder if Korean sites have it.

  2. (1) Terran add-ons break map symmetry (wall with add-on outside or inside). (2) They make the wall-in tetris more tricky on maps with large ramps. (3) How about base-internal walling to create obstacles for landed drops, or to create a quick path for your army to reach your mineral line?

    Otherwise great post. Appreciate the work!

  3. Good point on the add-ons. To be honest, I have a rather good idea of it works, but I’m not 100% certain about the interactions to make a post for it.
    Creating obstacle against drop is kinda out of scope. But for the record, I think it works against you more than your opponent.
    I am uncertain about the Korean sites as I cannot read Korean. =(

  4. hey hey! this is JaK (creator of the video). Thanks for making all these visuals, they’re really helpful for people like yourself who learn better this way.

    Spore crawlers are special. They are the only building that functions this way. The spine crawler used to be the same, but there was a patch around the release of HotS that changed this. Liquipedia may be out of date.

    Add-ons are considered 2×2 buildings for the purposes of walling and function exactly the same as a supply depot would.

    The video (and I assume this post) is made in order to map out how walls work rather than their possible implementations. There are near endless possibilities for cool uses of these principles. For example, making a wall that an scv can get through but not a hell bat might make it easier to run away from hell bat drops, etc etc Unfortunately this area of Sc2 is largely unexplored so I will have to do extensive testing with various walling ideas that I have before I will consider making a video about them.

    Thanks again for this post :D

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