Lesson I learned on that one is you have to control the area around you.Hopefully where you built this house there is a resurgence and others start rehabbing or demo and build new which props up your investment and limits losses.

The demo on that isn't bad, but you're talking about having to rig scaffolding (usually) to hang long boards on there.Is the roof "decking" bad?

Move on to the next deal.One good take away lesson: the owner told you $15k in repairs and it turned out to be a complete demo.

With some major demo and trash removal and a little rehabbing on one prop and probably a total gut on the other it could be a smoking deal.

Things will change as you start demo work.Lastly, keep changes to a minimum.

It was purchased with appliances, several building materials, and already demoed.

The find, the design, the demo ( I love demo), the building, and sourcing of materials at deep discount ( love this more). 

I would do all the demo and carpentry including installing the backer board and the tile. 

I've learned that I can probably save the most money in demo work myself after I talk with a GC.

Then you will have to pay the roofer to demo and reinstall which is where the $$ is anyway.