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Re: GBlist: Engineered lumber questn
8/4/97, George Newman of Hartwood, VA USA wrote:
>Dear list readers:
>I'm getting ready to build a house, and I *think* I want to use a good deal
>engineered lumber: finger jointed studs, I-joists, LVLs, and so on - and of
>course the usual plywood. I have two primary questions at the moment, and
>appreciate your thoughts.
>What about outgassing from all those glued-up members? I'm not talking about
>any particular sensitivity, just ordinary health concerns. I have some
>literature (several years old) from the American Plywood Association which
>basically says that if the product uses exterior (phenol) glue, don't worry
>I'd like to know the current thinking on this question, and would
>appreciate any leads or discussion.
>Second: The big three national brands of engineered lumber
>available in my area are Georgia-Pacific, Louisiana-Pacific, and
>Trus Joist MacMillan. I expect the products are more or less
>indistinguishable as far as quality (although if I'm wrong about
>that I'd appreciate someone letting me know!).
>What I'm wondering about - and hoping some of you can help me with, either
>the list or privately - is which of these companies has the best (least
>awful?) environmental record, including forestry practices as well as
>manufacturing. Anyone want to go out on that limb?
>Thanks very much for your thoughts.
>Hartwood, VA USA
It is my understanding that Trus Joist MacMillan has switched all their glues
over from phenol formaldehyde to Isocyanates which are chemically more stable
than the phenols, therefore less likely to offgas in finished installations.
This includes glue-lam beams, joists, "Parallams" and all their other
products. However, it should be noted that isocyanates contain a cyanide
group in their chemical structure with will release deadly cyanide gas if
exposed to a fire. Personally, I try to stay away from where there is a
Some people have been chemically injured by exposure to isocyanates or
isocyanurates in the manufacturing process or in the chemical industry.
Chemically stable or not, phenol or isocyanate--these folks usually refuse
to use glue-lams out of a general sense of self-protection. However, in the
larger picture, it is important to remember the fact that smaller trees are
used, scrap wood fiber is used, the structure is lighter in weight, the
lumber is more dimensionally stable, and these engineered components are
ideal for such further "green building" techniques as Optimal Value
Engineered(OVE) framing or Engineered Wall Framing (EWF). If effective
air-barrier techniques are used for gluing drywall to the studs and using
air-tight electrical boxes or other penetrations (a la Joe Lstiburek), this
may eliminate the concern for offgassing in the indoor environment. When
noxious elements materials cannot be eliminated, they can often be
David Kibbey, Environmental Building Consultant
1618 Parker Street
Berkeley, CA 94703
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