Drywall can be an air barrier if appropriate sealing/gasketing/caulking is done during construction. But this has nothing to do with keeping toxic materials from inhabitants. It's an energy conservation technique.

It's not airtight from day one, particularly because of all the penetrations that you see, like receptacles, light switches, light fixtures, fans, etc., plus all the ones you don't see, like behind your dishwasher and under your sinks. All of this stuff should be sealed in new construction to prevent air flow and energy loss, but it's often done inconsistently or poorly.

In any case, cracks are not going to increase your exposure to toxic materials. While I'm cautious and informed about environmental risks, concerns about what is coming through the sheetrock is not on my radar screen.

What kind of chemicals are you planning to put in the wall cavity?

Have non-toxic materials specified for the construction of your home, then the only thing you will have to worry about is if they used big enough nails to keep the roof from falling on your head.

@User I am planning on putting boracase and boric acid powder in the wall cavity.

Perhaps it would be better to define the problem rather than ask for opinions about one particular solution.

Where is the project located; what is the climate; is it new or old construction; what is the insulation, etc; and what kind of things are you trying to kill?

Joe Macker-

So you're concerned enough about insects that you want to put an insecticide inside all your walls? Is there some particular problem where you live that necessitates this?

See this thread.

We are in a low-risk area, so will be limiting termite protection to stainless mesh. We'll still be specing drywall as an air barrier. (But since I can't be everywhere at once and there'll be lots of drywall, it's a "stretch goal", as our former Premier liked to say about her failed promises.)

@worthy I had started that thread :-)

@User I am mainly concerned about termites and somewhat about typical insects like ants, cockroaches. Home in my area do a fumigation once every 15 years. Though it is not too bad, I want to do whatever is possible to avoid it, but at the same time be safe enough not to have any adverse effects on the residents.

It is a teardown re-model. Insulation is R-19 batts.

If there's a pressure differential between the outside and the inside, air will move through the wall.

Air-tight and sound-proof are terms that have little meaning outside of a testing lab.

I'm not a pest control expert by any means, but from what I understand, termites are seldom a problem as long as you keep wood well away from earth and monitor for signs of mud tubes. I hope someone will correct me if that's wrong.

The only time I had problems with cockroaches was when I lived for a while in an apartment building on the edge of the southern US. The memory. I'm not usually squeamish, but ewww.

In most temperate climates, you're unlikely to have them as long as you keep your house reasonably clean and are careful not to bring in any of them (or their eggs) from infested spaces. When I moved out of that h**l-hole apartment, I put a roach bait or two in the bottom of every box I packed, and left as many packed boxes as I could in storage for almost a month.

People eat borax as a health supplement. Boron is an element essential to human life. It is not toxic unless you drown yourself in it.

Whether it is a successful long term insecticide is another question. It used to be degraded by exposure to moisture, so there may be additives incorporated in this Bora Whatever that could be unhealthy.

People eat borax as a health supplement. Boron is an element essential to human life.

Wow. First I've heard of that. From what I just read, apparently people not only swallow it, they use it internally in other ways too. [shudder] I sure hope they're using USP purity stuff, and not Twenty Mule Team.

Iron is also an essential element, but I don't go around licking nails and porch railings. I didn't think I was especially squeamish, but neither metallic iron nor borax appeals to me at all.

Insecticides are valuable tools, but I wouldn't want them literally all around me, every hour that I was in my house. Besides, if any pesticide is overused, it loses its effectiveness as the pests evolve immunity to it. So while it's certainly your choice, I don't think I'd put an insecticide in my walls, not even something as theoretically harmless as sodium tetraborate.

I assume you meant to say Bora-Care.

How toxic is Bora-Care to humans or pets? The active ingredient in Bora-Care, disodium octaborate tetrahydrate, is a borate salt compound that is formed from a union of boric acid and borax. It has a very low toxic level to humans and pets, but is very effective against insects and fungus.

Wholesale use of chemicals throughout the walls of one's house to control insects gives me pause. I used to work for an environmental agency and we responded to an incident where a family had gotten seriously sick because the father thought it would be a good idea to mix a little pesticide into the paint when he repainted the interior. The sheetrock throughout the house had to be removed to make it habitable again. In another situation, a guy had put an anti-mildew agent on the interior of his sauna and was getting blisters on his butt whenever he used the sauna. I'm not saying that the idea of using borax in the walls will necessarily cause harm, but, if it was a good idea, you would probably see it being done as a standard practice. Personally, I wouldn't want to put a pesticidal chemical throughout my house, even if it has low toxicity to humans.