My understanding is that if a hub is 11 speed compatible, then spacers are only required if you want to fit a cassette with fewer than 11 cogs, as the cassette will be narrower than the 11 speed one.
I've no experience with Novatec hubs though, so hopefully someone will be along soon with a definite answer based on personal experience.
Are you using the Archetype rims? If so, great rim, and that is based on personal experience.
Good luck with the build.
Graham.