Problem with Planes and Light Leaking

Just want to say right off the bat that I'm no artist, so this might she be a beginner's mistake.

Right, I made a quick model mockup in blender and placed it into Unity 5 (current release). The model is a simple room with planes for the inside so that the backfaces are facing outwards. When I place the object into the scene (with both colliders and lightmaps generated) I get this strange leaking around the edges of my mesh (as shown in the attached .png file). The mesh renderer is set to "Two Sided" for cast shadows.

Things I've tried:

• Disabling lightmaps for the object
  
• Changing cast shadow mode from two-sided to one
• Changing how the model is unwrapped
• Changing the material

Things that have kinda worked:

• Changing the bias and normal bias to 0 removes some of the bleed.

Would appreciate any help.

 

You need some thickness on those walls.

 

Yeah, I added a solidify modifier in blender that simply adds .2 to the thickness which did fix it. I wanted to keep the planes however for the sake of workflow and number of 'gons.