Dr. Pejman Katiraei

We also have drywall.

So it turns out that up until the 1950s,

U.S.

homes and most homes in North America were built with plaster.

Plaster is basically concrete, which actually happens to be resilient to mold.

So if plaster gets wet, it doesn't get moldy as quickly.

Not to say there weren't mold issues in the old homes.

There were still mold issues for sure.

It turns out that drywall, because drywall is basically paper, paper, and calcium carbonate, I think, is sandwiched together.

Paper that's in drywall comes from tree bark.

It turns out that tree bark actually has mold spores in the bark.

And it turns out that drywall has some amount of mold spores actually just built into it.

So when you add water to drywall,

You can quickly get mold contamination because as soon as that drywall gets wet, presuming you don't have the fancy moisture mold resistant green drywalls or whatever they are.

But most common drywall, once that sucker gets wet, it can develop mold contamination quite easily within a few days.

And this is the environmental experts that I've talked to teaching me that.

And there's studies that look at that.

So our building methodology has also changed over the last several decades.

And combination of these things, the closed systems, the drywall, sadly nowadays construction techniques are not as good as they used to be because a lot of builders are just trying to throw up homes as fast as they can, right?

So sometimes they'll cut corners here and there just to cut down costs.