Mapping texture to repeat itself from a bigger map I'm working on a model for Cities: Skyline. It is my very first model for a game, as a mod or as an asset for my own game.

My question is about the texture usage on meshes. As this wiki says, the limit of map sizes is 2048x2048 though it is set for very special structures such as stadiums.

I'm modeling Brazilian National Congress. So far I have this model, not finished and, as you can see, partially textured.



Then I faced a problem with texture size used at the access ramp. I've set a texture and used the UV map to set the correct position of it and size. By this way, I could set a way bigger size making the tiles to repeat themselves as shown in this image:



But I need to use another texture for windows at the taller buildings for example and if I map the the texture as I've done with the ramp, it wont repeat that small portion of texture but the blank space as well, as shown here:



My question is, how can I get a texture to repeat itself selecting just a portion of it from a bigger map? Is what I'm doing right?
As everything will be packed onto just 1 texture, tiling would repeat the whole texture and this is unwanted. Nowadays engines don't have problems with polygons so if you want a part of that packed texture to repeat simply create the surface of many polygons each mapped to the same area on the packed image.

To utilize multiple tiling textures you would need support for multiple materials with multiple UV maps. Each section of model would then have different material with different UV map. Blender can do this but I have no clue about the format which you might use.