DIYbanter - View Single Post - "Stick Built," "Engineered Trusses," and Load Bearing Walls

According to :

36' wide house, trusses designed to span the whole width. The problem was
caused by the fact that there ARE other support walls. The only spot in the
house where the trusses actually span the whole width of the house is about
4 ft wide, after about 8 years the ceiling there cracked. The crack was
repaired and it would actually stay closed for a year or two. Final fix was
made by fabricating a beam out of plywood and 2x8 to span from the trusses
that were suported by the interior walls across those that were not . These
trusses were fastened to the beam with metal straps and the crack repaired
for the last time.

Beam is in the attic and the trusses hang from it.

If the interior walls had been built so they did not support the trusses
there probably would never have been a problem.

Sounds like you have an odd shaped house.

It's fairly typical that truss ceilings will "lift" off interior partition walls
on a seasonal basis. So, "floating" the trusses doesn't always work either.

There's a variety of tricks required to avoid such problems.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.