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Re: Exterior Timber Protection

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The Forest Products Lab (Madison Wisconsin) did some work on this issue
many years ago; including a 5, 10, 17 year outdoor exposure test.  They
looked at water repellant (w & w/o preservative) & paint ( w/  & wo WR &

The quick summary -- water repellant (basically wax disolved in solvent)
worked best.  Survived many years (>10) outside in Madison.
Preservative was not necessary unless environment was especially
conducive to rot (Southern states; high humidity).

The old formulation of Thompsons was solvent based but the new stuff is
waterbased to satisfy California air quality regs.  The old stuff really
worked.  Don't know about the new stuff.

The FPL gives a reciepe for home brewed WR.
The Abatron stuff is worth the cost; indestructible!

The FPL & USDA has design aids for exposed wood construction & the most
important thing that I remember from them is their reccommendation that
DETAILING for exposure is more important than wood species & chemical

Robert Kazanjy, PE  **Disclaimer: I speak for myself not UC-Irvine**
Senior Development Engineer
Civil & Environmental Engineering
UC Irvine

Roger Turk wrote:

> Roy Levy wrote:
> . > Consequently it is not clear to me if there is an inexpensive,
> reliable
> . > way to protect exterior timbers.
> Several years ago, the head of a large, international construction
> company
> was retiring to a mountain cabin in the cool (in summer, cold in
> winter)
> White Mountains of eastern Arizona.  For the cabin's deck he opted to
> go for
> treated lumber.  From what I heard, in one year the deck was a
> shambles and
> he replaced all the treated wood with redwood.
> A. Roger Turk, P.E.(Structural)
> Tucson, Arizona