Bsp

so I was planning a Bit section of a test level and I was using the BSP to plan so static meshes, I was hoping to convert them to static mashers and build the static mesh more in Blender, but exporting the mesh to FBX it ends up a mess and unusable holes all-over the shop and tris and seem to have no rime or reason to them, I like the idea of it because I can stick to a practical size and shape, any tips? it will be a low poly look