Masonry Magazine February 1982 Page. 34
SHELF ANGLE
CONCRETE
STRUCTURAL SLAB
CONTINUOUS
TRUSS
WALL TIES
Z WALL TIES
SPACER STRIPS
SOFT JOINT
FORM
FLASHING AND WEEPHOLES
SHORING
IN. (13mm) MIN
Built-in-Place Brick Soffit
FIG. 9
JOINT THICKNESS
Built-in-Place Brick Soffit Forming
FIG. 10
ing. The manner in which these problems are solved will determine how successfully the soffit will perform.
Flashing and Weepholes
Normally, soffits do not require flashing or weepholes. However, in some applications, both may be required, see Fig. 9. In other applications, only weepholes may be required, since the inclusion of flashing in some cases may impair the structural stability of the soffit. It can only be stressed that the detailer should always keep in mind the primary function of flashing and weepholes in determining whether they are needed in any particular application. Their primary functions are:
Flashing-collect and divert to the weepholes any moisture which might penetrate the element.
Weepholes convey all collected and diverted water to the exterior.
Connections
Whether the soffit is prefabricated or built in place, its connection to the structure is the most demanding detail for the designer to develop. Previously developed details may be totally inappropriate in the present situation. Connection details are critical in providing structural stability to the soffit. In detailing connections, it is important to keep one principal always in mind. That principle is: Keep It Simple. The simplest connection details are in most cases the most successful.
Expansion Joints
The installation of expansion joints, in most cases, should be avoided in soffits; however, it may be necessary to provide expansion joints when soffits are to be installed over large areas. The installation of expansion joints may cause problems in providing structural stability of the element and require additional connections to the structure. If it is necessary that expansion joints be installed in soffits, it is important to remember that the function is expansion control. This is provided by resilient joints which can be compressed to provide for the movement of brick masonry, especially during hot weather, due to thermal expansion of the brick masonry and return to its original shape when the temperature is cooler. Reinforced and grouted brick masonry does not usually require expansion joints.
6
Construction
Structural and economic considerations normally determine the construction methods to be used. While the detailer does not normally specify the manner in which the detail is to be executed during construction, the method of support and economic aspects determined by the detail will affect the method of construction chosen.
The method of supporting the soffit, both its permanent support and support during construction, has a direct bearing on the method of construction selected. The economics of constructing the element can be affected by configuration, structural support and materials selection. Economics in turn may well be the final determining factor in the selection of the construction methods employed.
When a soffit is constructed in place, it sometimes requires a complicated system of centering and falsework which must be left in place for a number of days. Normal practice is to provide spacer strips on the forms which locate each unit within the form and provide a joint on the exposed face suitable for tuckpointing once the form is removed, see Fig. 10. These strips should be the width of the joint and a minimum of 1/2 in. (13 mm) in height. After the units have been placed on the form, the upper side is grouted and ties are placed in the joints for anchorage to the structure. After several days of curing, the forms are stripped and the joints can then be tuckpointed. The number of days required for curing is dependent upon conditions at the site during the curing period and the materials used. See Technical Notes 7 for tuckpointing recommendations.
In some cases, the use of built in place soffits may be precluded. Then, prefabrication may be the most logical and economical approach, see Technical Notes 40 Series. This method of construction has been used very satisfactorily on many projects. On most of the projects where it has been used, the soffit is built integral with a spandrel cover and a sloped sill, see Figs. 11 and 12.