Slab Light
Slab Light changes how light passes through slabs and stairs on Fabric, so that directional light moves through them the way it does in Bedrock Edition.
What it does
In vanilla Java Edition, the solid bottom face of a bottom slab blocks light from travelling upward, so a torch placed beneath a slab leaves the space above it dark. For single slabs and stairs, Slab Light drops the directional limit, so light moves through them in all directions the way it does on Bedrock. Double slabs and full blocks are unaffected.
The mod is client and server, so the server and every player need it for lighting to behave the same way on both sides. Its files target Fabric for 1.21.1, 1.21.11 and 26.2, and the latest build, 2.0.0 for 26.2, was published on 2026-08-13. The code is released under the MIT License, but the project is not open source.
Removing the mod does not revert light in existing worlds. Only newly placed blocks revert to vanilla Java behaviour, while lighting already baked into built structures keeps the values it received, so the save should be kept in mind before uninstalling.
Key features
Directional light through slabs
Light crosses single slabs and stairs in any direction instead of being stopped by their bottom faces.
Bedrock-style lighting
Slabs and stairs light up the space above them as they do in Bedrock Edition, so torch placement works the same way.
Full blocks unchanged
Double slabs and full blocks keep their vanilla light behaviour, so only the partial blocks are affected.
Gradual change in worlds
Only newly placed blocks follow the new rules, while blocks already built keep their stored light values.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Who it’s for: Builders and players who use slabs and stairs in their structures and want their lighting to match Bedrock Edition. Server owners who run the mod need every player to install it too.
How it compares
LightSlabs is also a Fabric mod, with the same client and server environment, released under the MIT License and open source, for 26.2 – 26.3. Calcite Variants is another Fabric option that is client and server and MIT licensed, but it covers 1.21.11 – 26.3 and adds decorative blocks instead of changing light. Wool Stairs & Slabs is client and server and All rights reserved, for 1.21.11 – 26.2.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Slab Light | Fabric | 1.21.1 – 26.2 | Client and server | 2026-08-13 |
| LightSlabs | Fabric | 26.2 – 26.3 | Client and server | 2026-09-16 |
| Calcite Variants | Fabric | 1.21.11 – 26.3 | Client and server | 2026-09-20 |
| Wool Stairs & Slabs | Fabric | 1.21.11 – 26.2 | Client and server | 2026-06-23 |
Questions
Does Slab Light need to be installed on the server?
Will existing builds change after installing Slab Light?
Which game versions does Slab Light support?
In the catalog
Slab Light is one of 12,078 Decoration mods on ModsFinder, and one of 6,982 Decoration mods for Fabric. 13,894 mods support Minecraft 26.2.
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What the author says
Slab Light is a small Fabric mod that changes how light interacts with slabs and stairs in Java to match Bedrock behavior. In vanilla Java, slabs and stairs have directional light opacity - their solid faces block light from passing through. For example, a torch placed below a bottom slab won't light up the space…
Official listing
- Modrinth page
- modrinth.com/mod/slab-light
- Owner
- lefthandedleaf
- Published
- 2026-05-27
- Updated on Modrinth
- 2026-08-13
- Facts verified
- 2026-10-15