Kathryne, if that's your pick then that looks like a SFH. Kudos.
boyswillbeboys, any gap bigger than a half inch is enough room for weasels, rats, & other small critters to get in. Mice, even smaller gaps, down to a centimetre. The latter will eat your feed, the former bunch may go for your chickens. So build/repair with that in mind.
Mites, ticks, chiggers, etc are a problem w/ a lot of bare wood & gaps. Caulk the gaps you have so they can't hide inbetween the thin gaps in the beams/wood. Lastly, wood ash & soil together are a great dust bath to offer for your chickens.
Best of luck!