I am a railway modeller, I can design and add basic textures in SketchUp, no problems.

I needed to up the texture levels [quellenform istructions][1] put me right so now Walls with real life textures are possible.
I made a couple of how too videos aimed at the newbie like myself on [my YouTube Channel][2]. I am trying to pass on the knowledge and the response was great.

[![Test piece][3]][3]

My question is how do I convert a SVG/STL/DAE type file in Blender to a single mesh with no subdivisions so I can add displacement texture. I can then cut out windows using the Boolean method later once the texture is applied. I have Construction lines addon installed, would this help?

[![Type of drawing I want to convert][4]][4]

Import SVG, Limited dissolve works well.
I try and subdivide and only the edge gets subdivided?

[![SVG imported][5]][5]

[![Limited dissolve][6]][6]

[![Subdivided only edges affected][7]][7]


  [1]: https://blender.stackexchange.com/questions/262934/cutting-a-hole-in-a-wall-with-displaced-texture
  [2]: https://www.youtube.com/watch?v=w7I8ax1KWjg&list=PL2Mz1GBib5AsbP06-fgANDgQS0Ehhy90S
  [3]: https://i.sstatic.net/4PwjI.jpg
  [4]: https://i.sstatic.net/cskre.png
  [5]: https://i.sstatic.net/V2k5v.png
  [6]: https://i.sstatic.net/SwF9H.png
  [7]: https://i.sstatic.net/o2YXy.png