Can't tell why building is stuck

I have a building were the hearthlings build the floor, then stop. The building has a red exclamation balloon above it, but how do you tell WHY? I have all the resources, and since it’s just a floor there, they can obviously reach things…

The only thing different about this building vs. all the others that had no problem is that this one, the first story walls are clay instead of wood or stone. (I just tried knocking it down and rebuilding the template, and changing the first floor walls from clay to stone fixes it)

Clay houses require bricks, not just plain clay. Do you have a potter to make clay bricks?

Ah… that’s probably it. They should probably change the “resoucres required” icon in the builder to not be a lump of clay… :stuck_out_tongue: