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Re: Douglas Fir vs. Hem Fir

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About 11 years ago I had the opportunity to tour a PT plant in Stockton, CA.
The plant treated poles, dimension lumber and I believe sheet goods as well.
The dimension lumber typical to production at the time was DF.  It was
mechanically "perforated", placed on rail-trucks, rolled into a monstrous
pressure vessel, immersed in preservative, and then subjected to a BIJILLION psi
for a long time (overnight?).   I was impressed.   I haven't specified treatment
of drilled holes or end-cuts for PTDF members, although that is probably a good
idea, albeit difficult to inspect for compliance.  I always spec PTDF.

ps - related thread:  I know a local engineer who was poised to incorporate
redwood sole plates to circumvent the ambiguous nailing requirement for PT
members;  Hot-dipped galvanized nails for PT members (I don't. believe the
authors considered sole-plates).
 No PT..no hot-dip.





"Swingle, Mark" <Mark.Swingle(--nospam--at)dgs.ca.gov> on 07/19/99 02:38:57 PM

Please respond to seaint(--nospam--at)seaint.org
                                                              
                                                              
                                                              
 To:      "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>           
                                                              
 cc:      (bcc: Paul Reilly/D03/Caltrans/CAGov)               
                                                              
                                                              
                                                              
 Subject: Re: Douglas Fir vs. Hem Fir                         
                                                              






Anand Nene writes:
"I also know that P.T. mud sill specified on the job is invariably Hem fir."

PT Douglas Fir is readily available in the East Bay at least one major
supplier of framing materials to contractors (and I'm not talking about Home
Depot).  I'm sure other reputable suppliers also carry it.  When I saw it,
there was 2x4, 2x6, 2x8, 3x6, and 3x8 in PTDF, with the grade stamp and AWPA
stamp right on them.

One major problem with PTDF is that the treatment does not penetrate more
than about 
½" into the material.  All cut ends and bolt holes need to be
field-treated to provide protection from fungus and insects.

Regarding allowable stress properties, consult the NDS for the differences
between Hem Fir and Doug Fir.

Mark T. Swingle, SE
Oakland, CA