If a tenant were to test positive, do we as owners have a legal obligation to notify the other tenants in the building?

My personal take is: these houses have been there for 100 years already, there is a good chance they will continue to be there for another 100+.I also think there are some changes to modern building practices that make some modern homes less structurally sound than most older, i.e. 24 OC framing just always seems like it won't stand the test of time like 16 OC has. 

Hi, I am purchasing a commercial real estate (offices). here is the data:1.

To @Crystal Smith's point, appraisers only look as sold comps, so past data.   

Paul they are called "certificates of occupancy", and it's all public data on the .gov page.

Im excited to test what I have learned on BP by purchasing a single or multi family and renting it from day 1.The Newport home is a 3/1.5, 1044 sq/ft.

Get recent comparable sales data that supports your request for the lower valuation. 

I currently hold a 9-5 job you could say, i do access control, data communication, and security camera installation.  

All tested OK & the cost per test ran $150-$550.

As a tip, I like to add a list of sources/assumptions for the data I put in an analysis.