The problem is the grading outside is leaning towards the foundation, not away, and the framed supports are definitely getting wet.

If its laminate or engineered hardwood, and you are considering an area rug, it may help with insulating but the majority of cold being on grade, is coming from the perimeter so wouldnt adequately be addressed with area rugs.

I don’t remember everything I saw on the video, but I can recall: a downspout not finished bringing water towards the foundation of the home (probably causing mold inside too), a pipe somehow through a tree root, doors unhinged, chipping paint every where (here in Maryland you are in big trouble if there is peeling paint in a rental), siding dented, very low grade materials that will need to be changed with the first tenant turnover, among many other things. 

P.S.For reference as to what I mean when I say B or C Class neighborhood check out The Ultimate Guide to Grading Cleveland Neighborhoods.

To be honest, with all the HST tax charged on construction and resale, it makes the proforma challenging.For a simple rectangle in plan, with a very simple interior layout (straight run stairs, stacked plumbing and services) but high quality windows and builder grade interior finishes) what range of construction costs in $/sf would I be looking atHow difficult is it to sever a lot in Toronto (we'd be looking at lots in the range of 30'-40' frontage)?

What 'grade' of properties are you looking to buy?  

Maybe you shouldn't have quit school before the 8th grade. 

To be more specific, I have an early 90s home in Northern California with standard builder grade materials throughout for that era (solid oak cabinets, linoleum floors, gold accent hardware in bathrooms, tile counters, etc.)

Many of the questions on density, use, grade restrictions, setbacks etc, etc can be found in these Ordinances relative to the particular zoning district that the site is located in.

Assuming all hard and soft costs (drawings, permits, engineering, etc) and assuming mid-grade finishes (granite, hardwood, etc), we're building in Atlanta for about $60-70/sf and in Maryland for about $80-90/sf (though we're only on our first in Maryland, so I'm hoping that number will come down in the future).