Progressive Lightmapper resolution issue

Hi,
I'm trying to lighten a scene with baked GI using the progressive lightmapper and I'm getting some issues. As you can see, after baking, I get these strange black squares on the wall and even the lighting on the bar presents some artefacts. I've tried to play with the settings but the actual ones work very well for other scenes which have similar lighting (I have only three point light sources in the scene).
If someone could help me solve this problem I would be very gratefull.

 

Do things improve if you create new Lightmap parameters, se backface tolerance to 0 and rebake?

 

It worked perfectly ! Thanks a lot !

 

backface tolerance is not currect solution

Select your material and activate Double Sided GloblalIllumination for your model in Unity 2017+

 

Thanks for your reply. Can you explain me what is the difference between those two solutions ?

 

For double sided faces (in modeling) you must activate this option. backface tolerance was old hacked solution

 

Ok I understand, I will change to this solution.