This is ONLY done by a licensed plumber.
The buyer usually has to coordinate this. Sometimes the seller. It depends on the municipality.
When performed they need to submit the findings to the municipality and to the person paying for the test.
Again, only a licensed plumber can do this for you.
Some municipalities require the buyer to have one. Some municipalities require the seller to have it done before the property goes up for sale. The plumber may give you a video of the inspection. That will give you an idea of what is going on underground.
This is something we HIGHLY recommend that you do before you buy any property, ESPECIALLY houses built before mid 1980's.
This will show you if there are any breaks in the line, roots breaking through and blockages.
This type of repair can cost you thousands of dollars if there is a problem.
Prices vary depending on the plumber you hire, however, it is a small price to pay overall.
There are other ways of determining if there is moisture in the walls through staining, efflorescence and blistering plaster.
Regarding using infrared for viewing insulation, the short answer is a LARGE percentage of houses don't have insulation in the walls at all. It wasn't until the 1970's that insulation became normal practice.
There are more important tests to perform as part of the home buying process that will provide more useful, tangible information, that can save you money.
We don't test to determine the TYPE of mold.
However, mold in houses, especially basements, garages and attics, is common. Anytime we find mold or mildew, it will be put in the report. Determining what kind of mold really doesn't change the fact that it needs to be addressed.
There are mold remediation companies out there that are certified in mold detection and mitigation that do a fantastic job.
YEPPER - if possible.....
Usually the roof is reasonably accessible, so, yes, absolutely!
Some roofs are too high or too steep to walk on, BUT I will try to get a good look and make a determination of its overall condition and age.
The report will show what I can and can't access.
I take as many pictures as possible and include them in the home inspection report for with comments or notations. The report will also point out which concerns need the most attention.