Figure 8-7.Braoe rods.
Sag rods are used to hold the purlins and the girts
in a straight line. First, install the sag rods that connect
the two purlins at the ridge of the building. Each rod
must be attached from the top hole of one purlin
through the bottom hole of the adjacent purlin. Use
two nuts at each end of the sag rods-one on each side
of each purlin. Adjust the nuts on these rods, so the
purlins are held straight and rigid.
Next, install the sag rods between the purlins
below the ridge with the rod attached from the top hole
of the upper purlin through the bottom hole of the
lower purlin. Use two nuts on each end-one on each
side of each purlin. Follow the same procedure with
the sidewall sag rods.
Remember that the roof purlins should show a
straight line from end to end of the building. Do NOT
tighten the sag rods so much that the purlins are
twisted out of shape.
Brace Angles and Base Angles
After two or more bays have been erected, part of
the erection crew can be assigned to install the
diagonal brace angles.
To install the brace angles, lay the notched portion
against the frame flange and bend it into position (fig.
8-8). Diagonal brace angles are needed to support the
inner flange of the frame. Be sure to install them so
that they are taut.
While some members of the crew are installing
brace angles, other members can be installing base
angles. When assigned this duty, first, sweep off the
top of the concrete foundation, so the base angles will
set down evenly. Bolt the base angles in place with a
flat steel washer under the nut. Leave the nuts loose to
permit later adjustments after the wall sheeting has
Refer to the manufacturers specifications for
proper assembly and installation procedures for
end-wall framing, doors (both sliding and roll-up), and