From: John Rose <jrose36(--nospam--at)earthlink.net>
Date: Fri, 21 Apr 2000 23:23:47 -0700
The only valid source for design of wood trusses with glued plywood (not OSB)
gussets is Midwest Plan Service (Univ. of Iowa, Ames, IA), document MWPS-9
"Design of Glued Trusses." They have designs based on computer analysis per
Purdue Univ. analysis for pitched chord trusses of various spans and roof
slopes. It specifies chord species, grade, gusset dimensions and fabrication
specifications. Suggest using Ashland Chemical Co. "Isoset" adhesive, a
two-part (resin and catalyst) isocyanate structural adhesive recognized per
NER-165 for structural gluing. However, adhesive mixing and application should
be done under controlled conditions with supervision (structural engineer or
quality assurance inspection) to make sure it's done right. If local building
dept. has jurisdiction of building construction, they may allow site
fabrication under these conditions, or maybe not. Box nails or staples should
be used to fasten gusset plates in addition to adhesive, to provide pressure
for contact bond while adhesive cures; specs are in Midwest Plan Service
manual. Metal plate connected trusses from approved truss fabricator would be a
better choice for less hassle, and more typical component.
John Rose/APA, Tacoma, WA
Fountain Conner wrote:
> I have a (home builder) client who wants to build his own roof trusses,
> rather than go to a truss manufacturer.
> He wants to use glued OSB gussets each side of each joint. He wants to use
> Elmer's Professional Carpenter's Wood Glue. I've used Elmer's glue in
> re-gluing a couple kitchen chairs; I'm not impressed.
> I'm within minutes of telling him to go somewhere else.
> Three questions:
> 1. Is Surebond, SB-400, suitable for this application?
> 2. If not, do you have (or know of) a product which is?
> 3. Assuming we "can" glue the joints, is this an application in which OSB
> is appropriate?
> I have calls in to both Trus Joist MacMillan and Surebond on their
> products, but (wouldn't you know it?) their offices are closed today.
> 'Appreciate any of your comments.
> Fountain E. Conner, P.E.
> Gulf Breeze, Fl. 32561
> Phone 850-932-5547
> Fax 850-934-1916