Hi Johnchan,
I am unsure why you are considering even staying in an apartment that requires annual mould cleaning from one wall (doesn’t that tell you the wall itself is the issue) and whatever other cleanin you ‘have’ to do!
Is your rent very low or even free? As it’s a veritable death-trap your living in.
Considering you have young children, I would suggest you look to rent elsewhere for a property that doesn’t have such problems to avoid harm to you children’s lungs etc.
A fly screen is the least of your worries mate! Do yourself and your family a favour and find somewhere were moisture is not an issue. Your landlord and the OC ought to be ashamed of themselves!!
Thom