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With roof trusses, the
typical layout and spacing is 2 feet on center.
That means after placing the first truss all of
the trusses following are placed at 2 foot intervals.
With hip trusses,
the first truss is located at a specified dimension.
This is called the setback. This is the distance
from the front wall to the hip girder truss. The
setback is the dimension equal from the front and
either side which forms the 45 degree angled ridge
line. When looking at the hip truss the distance
from the end of the truss to the flat top of the
truss is the same as the distance from the front
wall to the hip truss. Each hip truss setback will
increase by 2 feet until you reach the center dimension
which is half the length of the truss. If a truss
span is 30 feet in length and it is placed at the
point at which the 3 ridges come together the setback
would be 15 feet, the distance equal from the front
and either side.
The next truss
down in height and closer to the front wall is placed
at 13 feet and so on until a minimum distance is
reached for the placement of the hip girder, about
5 feet for this layout. The example given above
places the hip girder at 6 feet. Since the truss
span is 22 feet, the center of the truss is 11 feet
but the last hip truss is at 10 feet and the first
peaked truss is at 12 feet, which means the 3 ridges
meet between trusses which is not a problem since
most builders can do it either way, from the top
down or from the bottom up.
