You will need to close the gaps under the roof to the sides of the walls. Critters will find their way inside and attack your birds. Also you could put 1/2" hardware cloth backing behind the windows - so if open, nothing can get inside. Welcome to BYC
If you haven't been to the Learning Center yet, check it out...it's full of interesting articles on poultry care. And if you have questions, always feel free to ask.