Good Morning. What is the scope of the sunroom project? It is an existing porch they are enclosing? Or are they building in an entirely new room? That is going to make a big difference.
Typically, the full enclosure of an existing patio into a sub room requires permits. You have to be concerned about the ingress / egress from a fire code point of view as you have now created a second exit to get out of the home. Now if they don't have a door, and it is an existing patio, just being enclosed, I don't know that I would be too worried about it.
On these projects what I have seen as trigger points are the full enclosure creating a new exit, addition of electrical for cieling fans, or porting the existing HVAC system into the room.
What's the overall scope? I would be happy to chat more about it.
Dave