When it gets that bad that I have to wear basically a chemical suit then I note the dangerous conditions that exist and move on. You pretty much
know what your going to find…elevated moisture readings, organic growth, deteriorating framing members and 9 times out of 10 the same organic growth in their duct system.
Majority of the homes I inspect are crawlspaces…between termites, powder post beetles, organic growth and dumbarse plumbers who like to test our their new saws-all…the foundation section is usually my most notable entry in the report.
Our GC company does encapsulations…there are several types / levels.
any time you find anyone installing 6mm and calling it encapsulation then I about guarantee its done wrong. We use reinforced 12mm on the walls and 20mm on the floor with taping overlapped joints, insulated the walls, around the band joist, introduce conditioned air, install a dehumidifier that is programed which drains through an emergency drain line that is also sealed to prevent unwanted pest from using same to enter the crawl.
Additional bells and whistles can be added for extra $$$$.
On average you are looking at $4000 - $5000 depending on the size of the home and conditions to install in an existing crawl.