Masonry Magazine January 1981 Page.16
Exterior Loadbearing Walls
Cavity wall construction may be used for exterior loadbearing walls. The exterior wythe is subjected to greater temperature fluctuations than the interior wythe used for thermal storage. For cavity wall construction, both the interior and exterior wythes may require expansion joints for thermal movement.
Exterior Non-Loadbearing Walls
Cavity wall construction may also be used for exterior non-loadbearing walls. East or West-facing walls may be positioned in the structure so that they are exposed to morning or afternoon sunlight for direct gain storage. Typically, passive solar buildings require a large amount of additional interior mass which may be unexposed to direct sunlight. This mass provides supplementary thermal storage, resulting in a thermal flywheel for reduced interior temperature fluctuations. The interior wythe of the cavity wall may be considered when determining the amount of additional mass.
Interior Loadbearing Walls
Typical details for interior loadbearing brick masonry walls are shown in Fig. 2. These details are similar to conventional loadbearing construction. Wood floor joists bearing on the brick should be fire cut.
A roof construction detail is provided, offering the option to use a skylight to expose the brick masonry loadbearing wall to sunlight. The interior brick masonry wall may be exposed to direct sunlight through South-facing windows and doors, or a clerestory may be used, depending on the distance from the South-facing wall.
The use of interior loadbearing brick masonry construction does not require any special consideration over and above conventional construction. The only exception is that provisions for thermal expansion may be required.
Interior Non-Loadbearing Walls
Interior non-loadbearing brick wall construction is quite similar to conventional brick veneer construction. The brick veneer should be constructed as shown in Fig. 3. The brick masonry should be continuous through all floor intersections so that all the brick masonry bears on the foundation or foundation wall and complies with building code fire safety requirements. Additional information on brick veneer construction is provided in Technical Notes 28 Series.
The requirements in Technical Notes 28 Series apply to interior brick veneer construction, except that the requirements for the effect of weathering may be disregarded. The backup material; wood frame, metal stud, etc., should be constructed as in conventional construction.
If the interior brick veneer is constructed with wood frame or metal studs without sheathing between the backup and the brick veneer, the 1-in. airspace between the brick and the backup, as recommended in Technical Notes 28 Series, may be eliminated. If the brick veneer is constructed with a framing system that requires sheathing on the side to be veneered, it is recommended that a 1-in. airspace be maintained. This provides "finger room to facilitate the laying of the brick. The use of the sheathing on the side of the backup material which is to be veneered may be required to provide the appropriate structural rigidity of the backup system. This sheathing may also be used to increase the fire resistance and sound transmission classification of the wall.
Interior Flooring
Typical details for brick flooring are provided in Figs. 1 through 6. The interim floor details show mortarless paving, and the ground floor details show brick masonry set in a mortar bed. These details are interchangeable. The interim floor detail shown in Fig. 3 is a typical detail for mortarless brick paving in a sand bed. The difference in thermal performance of mortarless paving as compared to paving units set in a mortar bed is insignificant. There may be a slight reduction in heat transfer from unit to unit, but this will typically have a negligible effect on overall thermal performance of the floor system being used as direct gain thermal storage. Paving units are used as the flooring in the thermal storage wall details, Figs. 4 through 6. These paving units in combination with glazing incorporated into the thermal storage wall for daylighting and visual contact with the exterior may be used to form a direct gain system. The brick flooring may also be used to achieve the additional interior mass required by many passive solar heated buildings.
A soft joint should be installed around the perimeter of the brick paving, mortarless or set in a mortar bed, to provide relief of the stresses due to thermal movement, deflection and differential movement between the brick flooring and adjacent construction. Additional soft joints may be required for thermal expansion.
Supporting brick masonry paving on floor systems requires sufficient stiffness of the system to adequately support the additional weight in such a manner as to satisfy the minimum deflection requirements of the brick paving. For mortarless brick paving, the maximum deflection should be less than or equal to L/360. For brick paving set in a mortar bed, the maximum deflection should be less than or equal to L/600. For wood floor systems supporting brick flooring, the sizing and spacing of the floor joists should be adequate to support the additional weight, satisfy the floor joist structural requirements and the deflection requirements of the brick flooring.
The floor connection details shown in Figs. 2 and 3 should be such that the top surface of the brick flooring is level with other floor finishes. If this is not desirable, or possible, the appropriate riser distance between the surfaces of the different floor finishes should be provided to comply with the governing building code.