In those cases you would need an extension from the municipality or lose your non conformity. 

It almost doesn't seem worth it unless I find myself in a position down the road where the cost of building is less of a burden.If I sell I probably would only get $225k for the duplex once built (minus fees) but I'll have paid $275k so I sort of stand to lose an equal amount if not a little bit more

That is because YOU are the one who will lose your property if they are not paid.

Make sure you have at least one contingency left or you’re going to lose your earnest deposit. 

Well, I worked really hard for my real estate, so its really scary to lose my rentals.

So for example, if you buy a property for $150,000 that's worth $200,000 (i.e. 75% of it's worth) and it loses 25% of its value.

@Lindsay GittensVery common, I’m planning on doing this, try to work with people with something to lose like credibility if they screw you over or possibly partner with someone boots on the ground.

It's hard to lose money when you're doing it yourself because your costs are so low.

@Isaac Gwin don't lose heart!

That will get the tenants attention because if they get evicted while on Sec. 8 they lose their Sec. 8 and they may just hightail it out of there.