Restrict certain material to section of terrain

Development Asset Creation
,
1

I want to make a city scene, how would I restrict the grass material so it can only go around the houses or whatever and not spill out into the street?

2

You can paint it on (or out) with the landscape tools.

3

How do I do that though?

4

This may help you:
https://docs.unrealengine.com/latest/INT/Engine/Landscape/QuickStart/4/index.html