so it’ll be a pent roof, flat with no pitch, but the back wall is 25cm lower than the front and the entire strip below the roof on front and back will be hardware cloth. I’ve not done the sides because when we get strong winds, that’s the direction they come into my garden from. The window will open with hardware cloth behind it, and the big door will be open during the day anyway as the whole thing will sit inside a secure and covered run.What's the pitch on your roof?
Where do you intend to put the vents and how will you shield them from rain?
I would suggest adding large roof overhangs and leaving both the triangles directly below the roof on the sides and the top section of the taller wall completely open (screened with hardware cloth), to provide draft-free ventilation above the chickens' heads where it will do the most good.