Climate Change seems to have caught up with Primitive Technology as well. Now they need to either prepare for the rain season or find different building materials.
PT could break the rules for spores IMO. Using masks in such situations is not an advantage, but the aversion of a danger.
I think the references to an increasing pile of bricks and mortar, and how the brick hut stood up well in the rain implies the next project is another brick hut.
He mentions (in the comments of the video) the catch-22 of needing the thatch to last long enough to make enough bricks to make a brick and tile workshop that doesn't need thatch.