My editor, Kim, asked me a while back to look into underlayment. She said she’s gotten a few questions on it, mostly in terms of off gassing issues.

There is a lower risk of troublesome emissions coming through because there is a floor on top blocking transmissions.

That’s a tough one to address broadly because there are so many different kinds of underlayment, made of so many different types of material from cork or wool to plastic or foam or rubber or felt, or even metal—that aluminum lining, remember? However, as a rule of thumb, there is a lower risk of troublesome emissions coming through because there is a floor on top blocking transmissions. After all, most tests show that even a thin piece of paper will serve as a significant barrier to emissions—think what a thick piece of flooring will do! And, again, as a broad rule of thumb, formaldehyde specifically is not generally a major concern from these materials. There may be other VOCs coming into play, depending on the material, but most of these products are rarely made with formaldehyde.

That said, many companies providing underlayment are now testing that underlayment to CA Section 01350. So like with most building products these days, if this is a point of concern, you can look for a product that passed Thirteen-Fifty.

So I’m afraid I can’t give a lot of specifics on VOC emissions from underlayment, but I can talk about other green features of the product.

The choice of underlay—or underlayment if you prefer—can have a big effect on the performance of a floor, and while it may not be as exciting as choosing the wood flooring itself, customers should be encouraged to put a certain amount of thought and homework into the underlay as well. A good place to start is this oldie but goodie, a Hardwood Floors article from 2008!

In some installation methods, notably floating, the underlay is a critical component of the flooring system because it is the cushioned layer that the floor actually "floats" on. However, underlays can also perform several other functions: they can work as a vapor barrier, provide additional underfoot comfort, add insulating value, correct minor subfloor irregularities, help minimize elevation changes between different flooring types and they can provide soundproofing.

(Installation reminder: The acoustic damping and vapor retarding properties of any underlay will be undermined in a nail-down installation, because the fasteners will help to conduct sound and also puncture the moisture retarder. The underlay will still perform both functions, but not as effectively as with other installation methods.)

So how is underlay green-related?

Better moisture control can lead to a healthier home.

Setting aside material choice or emissions control, first and foremost, all of these features can lead to a longer lifetime for the flooring. A comfortable, well-installed floor is a floor you’ll use for a lifetime. And we all know that one way green can be defined is getting a long use out of your resource.

Better moisture control can lead to a healthier home—less chance of mold and mildew developing, a less attractive environment for pest and insects.

And sound control can help make a more attractive environment for the human occupants of the home. This has become a well-recognized “green” feature with LEED now offering credit categories of "acoustic comfort" or “acoustic performance.” Next week we’ll outline the way to view sound and try to make it easier to talk about. (And with good sound control, we can even yell about it and not bother the neighbors.)

Elizabeth Baldwin has over 20 years of international wood sourcing experience. Very widely traveled, her résumé's "Special Skills" section includes "the ability to eat anything from raw horse to deep-fried scorpion." She serves as Metropolitan Hardwood Flooring's (metrofloors.com) ECO (Environmental Compliance Officer) and deals daily with the "green alphabet soup" of today's industry: FSC, CARB, LEED, and much more. She blogs for Hardwood Floors on all things green (and, as she says, " 'grey' and 'blue' and almost every color except 'black and white.' Nothing in this world is black and white, particularly not 'green issues.'")