Weird mesh

[jo2ny]

Hello,

I'm having trouble with some meshes.

I attached a picture. You can see in it that for my model some of the wall elements were meshed only on their borders. Why is that?

Thanks in advance

P.S. 

I tried to remesh localy, but the same problem. I tried to modify the mesh size, type... It still happens

[Artur.Kosakowski]

I assume that the cause are some inaccuracies in entering the model. Please try to use the detailed correction option to adjust the walls to a single planes. In addition you may switch off the use of  the regular mesh.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.