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Re: WOOD - Roof Repair

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Richard Lewis

The roof is sagging because the tops of the walls have spread as the walls
tilted outward due to the thrust from the roof.  Instead of jacking the roof,
how about pulling the tilted walls back together?  Perhaps this could be done
at a number of points along the outward-tilted walls by use of hardware that
includes bearing assemblies on the outside of the walls, and threaded rods and
nuts such that tightening the nuts shortens the distance between at each
bearing assembly.  

I think its true that permanent deformation of the rafters may make
elimination of all of the sag impractical.  That's less important, though,
than correcting the deficiency that the sag has brought to light.  Adding
tension capacity across the span as you have in mind seems very important --
earthquake forces acting on the walls added to the roof thrust forces on the
tops of the walls could lead to serious damage to the church building unless
the walls are restrained to the diaphragms.  

If anchors to secure the walls to the framing at the ends of the new trusses
are the anchors you were discussing in your other message, and if the anchors
will be at the tops of the walls (a very fragile location in a stone wall),
send me a private message with more detail -- perhaps I can share some ideas
from my experience that may be helpful.

Nels Roselund
Structural Engineer
"Only works on buildings that are older than him."