@Dedric Polite These are old homes/buildings, so as far as due diligence goes, the lead and asbestos are something you have to examine. 

I hope to bring value to others in the REI environment with my educational background in Architectural Technology and professional background as a Project Manager.A little bit about my experience: Although outdated, I obtained my BCIN when passing the House/Small Buildings and Designer/Legal Ontario Building Code examinations.

@Josue Vargas  ... you are letting a little "Poor Dad" creep into your advice: "before going further, please, graduate, find a job, work hard, pass your EIT and PE examinations, get the experience you need to be called an engineer". 

This is from a top UCSF doctor who has written books examining the problems with trials and studies:"Last 15 years an increase appetite for uncertainty at time of regulatory approval for drugs and drug products. 

However I would recommend examining every property in the comparable and throw out the ones that are not actually comparable or similar.  

I went to the planning department to examine the permits and noticed that when the permit for the home was pulled, it specifically said the manufactured home was to be removed upon completion of the home as it was zoned single family.

We have examined the attic and the rafters and see  no evidence of a leak anywhere.  

I am a criminal defense attorney in Southern California so I needed to cross examine him in person.  

I would recommend asking for referrals, and don’t just call on the phone - drive by the sites, talk to the property owners, and examine the work that was done.I would also encourage you to ask him if this is his standard way of doing business, or is his upfront money request based on the relatively small cost of the job.

But your tenant was concerned, and they did the right thing by contacting you and you did the right thing by getting someone out there to examine the issue.