The slab has cured nicely; cool temperatures and a bit of rain have ensured that the slab had no reason to cook off too quickly.
Walls started going up today, 6 courses per day maximum. Window and door openings have been measured and set, and the window and door have been ordered; they’ll be ready in January/February.
Stacking blocks to make the work quicker 
Doorway marked, left wall being tied to the back 
Progress by lunch time 
Almost done for the day
The new walls are tied to the old ones with tie-bars, and there’ll be a ring beam too. A dry space may well be possible by end of Friday, assuming the days stay dry – walls can’t really be built if it’s raining.