Figure 7-17.-Typical beam and girder form.

stripped and the bottom left in place until the concrete has hardened enough to permit removal of the shoring. The latter type of form is preferred, and details for this type are shown in figure 7-17. Although beam and girder forms are subjected to very little bursting pressure, they must be shored up at frequent intervals to prevent sagging under the weight of fresh concrete.

The bottom of the form should be the same width as the beam and should be in one piece for the full width. The sides of the form should be 1-inch-thick tongue-and-groove sheathing and should lap over the bottom as shown in figure 7-17. The sheathing is nailed to 2-by-4-inch studs placed on 3-foot centers. A 1-by-4-inch piece is nailed along the studs. These pieces support the joist for the floor panel, as shown in figure 7-18, detail E. The beam sides of the form are not nailed to the bottom. They are held in position by continuous strips, as shown in detail E. The

Figure 7-18.-Assembly of beam and floor forms.