Q: I am looking for formaldehyde free plywood...exterior grade...t and g suitable for flooring and sheathing. Do you know where I can find it?

A: (Leon) To the best of our knowledge no formaldehyde free plywood products are produced. However, formaldehyde emissions from Exterior and Exposure 1 APA trademarked plywood panels are very low.

Q: We are planning our earthen/concrete composite house, here in the monsoon climate of the PNW. We are considering an EPS product, but are unsure about the use of polystyrene, as we don't know it's properties and have sensitivities to chemicals and outgassing problems. Any information on this, perhaps how healthful a substance this really is?

A: (Kelly) EPS is very commonly used in the building industry, especially with Insulated Concrete Forms (ICF's) and Structural Insulated Panels (SIP's). I'm not crazy about the stuff for several reasons: It is a highly industrialized material that requires energy to manufacture and transport, etc.; it is very toxic if it ever burns; it could potentially outgass. For this reason I would recommend using a more benign substitute or making sure that it will be imbedded within the structure in such a way that it is less likely to outgass into your living evironment. The shotcrete panel systems above could be a good way to go; the EPS is encased in concrete and the mass of the concrete is available to moderate interior temperatures.