Understanding Terrain GW/WTC etc

Hello All,

Old timer trying to understand new things. Terrain in 10E 40k has changed a lot since 2E, and now I am trying to understand terrain maps.

So apologies for the list of questions ahead:

1. Understand footprints, but what’s the point of the footprint?
2. WTC clearly defines ruin size on the footprint but GW does not, correct?
3. Height of terrain, is there a max height? (Or just a min height). Is there a requirement for floors? What’s the point of the height?
4. The blue areas in GW/WTC is for terrain under 2 inch’s. So broken walls/barriers? Just trying to think what to model. In the game, what’s the difference between this and the ruins L or U shaped?
5. Windows? Allowed? Shoot through? Some WTC has it, some just has no windows (which makes it really boring to look at)
6. Troops can’t mo e through solid walls on the L/U shapes but can move over the barrels/barriers in blue areas.

I have some modular terrain so just wanting to understand how to build it onto the footprints.

Thank you