On my last purchase, I was able to get the roof replaced, the entire sub floor of a rotting bathroom replaced, the crawl space cleaned with new vapor barrier, and rodent/pest check/prevention.My basic procedure for submitting an offer is to have my agent and inspector point out every little thing.

@Pavel Sakuretsbe careful with the vapor barrier over a zip wall barrier  might check with zip wall first and make sure you do not create a trapped zone where moisture can not get out  ... enjoy this post...thanks

PVC pipe is pretty cheap and easy to install.A 90% and up furnace will also need a drain line for the *furnace* - they pull enough heat out of the exhaust that the water vapor condenses out and doesn't go up the flue. 

Since concrete is porous and water vapor can penetrate, vapor barriers may be desired under the floor.My house had an old garage transformed into part of the house and the skids were on tar. 

While I'm all for encouraging investment in our city (assuming of course it isn't slumlord type investment, we don't need any more of that) you're talking about what is most likely a full time endeavor and as far as long term appreciation, unless you hit it just right and hit an area that has a big gentrification component down the road, long term appreciation of any substantial amount is unlikely, so you're left with cash flow and when you're normally talking about older to just plain OLD housing stock, thus higher or much higher annual maintenance costs to keep a safe and habitable rental property and keep you off of the city's "slumlord radar" which you DO NOT want to get onto, combined with tenants who are often a real crap shoot (yes, you CAN find great tenants who care about keeping a decent home even in the poorest parts of town, we have decent people in all parts of this city who are trying to build a better life for themselves and their families, yet you will also run into many who don't care, who bring unforeseen issues which seem to ALWAYS=extra, unforeseen costs to the landlord, whether you're here on the ground fixing the issue yourself or DIY plus pro help when necessary, or long distance via a PM (always going to likely cost much more)) and the wonderful looking cash flow component, which due to the very likely lack of any appreciation component, is all that's left for profit potential, also can quickly vaporize in front of you!

I guess I mean frame and vapor barrier.

I've used Vapor Pest control in the past.

Getting the proverbial 100% finance, no money down loan is vapor ware and a fairy tale in my book - - unless you consider a hard money loan to be an option.

Best to tear up the existing HW and lay your new floating floor over that (with the appropriate vapor barrier/foam padding).

Water and mold everywhere; they had to remove the vapor barrier and bring in drying fans.