You would tape all seams in each layer and use a sealant around the perimeter of each sheet to achieve your air barrier.

I have gotten into the habit, however, of leaving a bottle of the same home insect perimeter spray that I use on my home and tell them that it works well for me.  

Decided to put some of that down around the perimeter.

Concentrated on outside the perimeter areas.I'm a Real estate agent and a property manager.

i rent rooms out in my house, and once had a tenant who brought bed bugs in. i live in a 2 story, 5 bedroom house with a basement, and i successfully got rid of them with diatomaceous earth, but it was messy and time consuming. this is what we did:1. got rid of some furniture that was infested(make sure to rip or spray paint so no one grabs infested items off the curb. 2. dusted the perimeter of each room with diatomaceous earth. so the bugs couldn't travel to different rooms(2 of the bedrooms had no signs of bugs). they can also get in the walls, so we removed all switch and outlet covers and puffed the dust into the walls, then we got some foam outlet/switch inserts(which also help with insulation) , covered those in diatomaceous earth, and installed them under all the switch/outlet covers. 3. beginning with the "safe" rooms that didn't have signs of bugs, we washed all bedding, clothes, curtains, etc.

@Georgui Kasaev Right now I'm mostly focused on Gwinnett county, but I'm open to do business anywhere East of the perimeter.

This is part of telling the story.With each shot, scan the entire perimeter of the frame to be sure there isn't something distracting that you can eliminate by moving a bit. 

Concrete along the perimeter of the house is cracking.

You could also leave the black berry bushes around the perimeter as a natural fence and then spread wild flower seed and sod a small portion of the yard.

An example might be: 45 sq. ft of mold along a perimeter wall (dining room, living room wall adjoining the outside of the house).