# Light through wall

**URL:** <https://forums.unrealengine.com/t/light-through-wall/489337>\
**Category:** Rendering\
**Tags:** stationary-lights, wall, unreal-engine, lighting-problem, question\
**Created:** [September 29, 2021, 1:26pm UTC](https://forums.unrealengine.com/t/light-through-wall/489337 "2021-09-29T13:26:05Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![srhrs](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@srhrs](https://forums.unrealengine.com/u/srhrs)\
**Post date:** [September 29, 2021, 1:26pm UTC](https://forums.unrealengine.com/t/light-through-wall/489337/1 "2021-09-29T13:26:05Z")

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Hi,  
I’m having a problem with a stationary directional light on stationary mesh and I’m unable to fix it. Light filters through the wall, but only one; others don’t have the same problem even with the same exposure. There are also some small shadow artifacts.

I read that it could be a problem with the mesh actually having a gap so I recreated the walls.

I also read that the light on two sides should be activated.

I also tried to remove the reflection sphere, increase the resolution or set a specific lightmap.

Nothing worked. I hope someone can help me.

 ![349593-schermata-2021-09-29-alle-010136.jpg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/6/1/1/6115490fa50de2bcd599e162a982d31f9c97394c.jpeg)

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**Author:** ![ClockworkOcean](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/clockworkocean/32/1169999_2.png) [@ClockworkOcean](https://forums.unrealengine.com/u/ClockworkOcean)\
**Post date:** [September 29, 2021, 6:56pm UTC](https://forums.unrealengine.com/t/light-through-wall/489337/2 "2021-09-29T18:56:05Z")

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I think you’ll find it happens elsewhere if you move the light.

Does the mesh have depth? If it’s just a plane that won’t help.

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**Author:** ![srhrs](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@srhrs](https://forums.unrealengine.com/u/srhrs)\
**Post date:** [September 29, 2021, 8:19pm UTC](https://forums.unrealengine.com/t/light-through-wall/489337/3 "2021-09-29T20:19:37Z")

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Thanks for the reply 🙂

It’s a mesh imported from Blender: I started from a cube for each room that I solidified individually and then join it, in doubt that it did not recognize the thickness. The first time I created it I always started from a cube and I worked only with extrusion, yesterday I thought changing the method.

The strange thing that happened is that once I imported into UE4, some walls were gone and flipping the normal didn’t help so I solidified again with a small thickness and the walls reappeared.

I tried to put a very thin cube in the middle of the problematic wall: it worked until I built the lights and then the problem returned.

I tried to play with the light a bit to see if there is other bleeding on other walls: Yep, the light thruogh everywhere.

 ![349637-schermata-2021-09-29-alle-220845.jpg](https://d3kjluh73b9h9o.cloudfront.net/original/4X/3/e/6/3e6b3c6e886e8ce7b643dcd6161910aa17a2fe79.jpeg)

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**Author:** ![srhrs](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@srhrs](https://forums.unrealengine.com/u/srhrs)\
**Post date:** [October 13, 2021, 11:28am UTC](https://forums.unrealengine.com/t/light-through-wall/489337/4 "2021-10-13T11:28:24Z")

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RESOLVED

I solidified planes to create the walls and didn’t join them. I made each wall rest on the floor and gave it thickness. I then covered the thicknesses that remained visible from the outside with a cover made from a simple plane, extruded around the entire perimeter of the house. I exported the meshes without joining them.

I think the mistake was that the walls rested sideways to the floor and perhaps also that it had no thickness.

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**Author:** ![DEICIDER78](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/deicider78/32/1006174_2.png) [@DEICIDER78](https://forums.unrealengine.com/u/DEICIDER78)\
**Post date:** [May 1, 2026, 3:14pm UTC](https://forums.unrealengine.com/t/light-through-wall/489337/5 "2026-05-01T15:14:27Z")

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mmmmm… Try my solution, you can find it on my channel!

[How to fix light through walls without adding solids or enlarging the walls](https://www.youtube.com/watch?v=SoD9WwpuFEg)