Masonry Magazine February 1982 Page. 31
SEALANT
15 MIN
WOOD OR
STEEL FRAME
BRICK SILL
WEEPHOLES
1 IN. (25 mm)
MIN
METAL ANCHOR
SEALANT
15 MIN
BRICK SILL
FLASHING
FLASHING
WEEPHOLES
1 IN. (25 mm) MIN
Sill in Frame/Brick Veneer Construction
FIG. 3
Sill in Cavity Wall Construction
FIG. 4
The appeal of the structure may also be achieved by the use of a contrasting color or texture or by use of materials other than brick for the sill. Esthetics may also be affected by the use of a different bond pattern than that used in the adjacent wall. See Figs. I and 2.
Materials
Sills for use in brick masonry construction are typically brick, concrete, stone or metal. The selection of material is primarily dependent upon the required esthetic effect. But it is also important to note that metal, concrete and stone sills normally require fewer joints than do brick sills, and therefore provide fewer potential avenues for water penetration. Once the decision of which material to use is made, then decisions concerning the quality of that material can be made. Whichever material is selected, it should be of high quality. A discussion of brick and mortar properties is found in Technical Notes 7B.
Flashings for use in sills can be of a number of materials, such as copper, lead or plastics, see Technical Notes 7A for additional information. Aluminum and asphaltic-impregnated felt are not recommended for use as flashing materials. Aluminum is not recommended since alkalies in the cement of the mortar may attack it and cause corrosion. Asphaltic-impregnated felt is not recommended because it is easily punctured during construction. For the same reason, plastic films of less than 20 mil thickness should also be avoided. Once the flashing has been punctured, it ceases to fulfill its function, thus in place flashing should be inspected for punctures and tears, and appropriately repaired prior to laying brick masonry on the flashing. Also, some plastics are subject to continued degradation after having been exposed to sunlight for an extended period of time.
Details
General. Since the primary function of sills is to divert water away from the building, the top surface should slope downward and away from the building. In the case of brick sills, see Figures 3 and 4, the slope should be at least 15 deg from horizontal. This may vary somewhat according to the sill configuration of the window unit, particularly in the case of wood windows. The sill should extend a minimum of 1 in. (25 mm) beyond the face of the wall at its closest point to the wall, see Fig. 3. In some instances, it may be necessary that the brick units at the ends of the sills be uncored units so that no cores are exposed to view.
When concrete or stone sills are used, they should be sloped away from the building, and also sloped from the ends toward the center, see Figs. 5 and 6. The slope away from the building should be at least 15 deg from horizontal, the slope from the ends should be 1/8 in. (3 mm) to 12 in. (300 mm) toward the center of the sill. For sills longer than 4 ft (1.2 m), the slope should extend for at least a distance of 2 ft (600 mm) from the ends, see Fig. 6.
Flashing and Weepholes. In general, when a collar joint, cavity or air space is interrupted, such as at sills, at the base of the walls, at lintels over openings and at
SEALANT
CONCRETE OR
STONE SILL
FLASHING
15 MIN
1 IN. (25 mm) MIN.
WEEPHOLES
Concrete or Stone Sill
FIG. 5
DOVETAIL
METAL
ANCHOR
FLASHING
TURNED UP
BEYOND
END OF SILL
3