General Analysis & Design Requirements
Multiwythe Walls (composite)
Wythes not bonded by headers shall be bonded by wall ties provided as follows:
Wire size Minimum number of ties required
W1.7 (9g.148) One wall tie per 2 2/3 ft2 (0.25m2) of wall
W2.8 (3/16 .187) One wall tie per 4 1/2 ft2 (0.42m2) of wall
The maximum spacing between ties shall be 36 in. (9.14 mm) horizontally and 24 in. (610 mm) vertically.
Cross wires of joint reinforcement are permitted to be used as wall ties. The use of rectangular wall ties to tie walls made with any type of masonry units is permitted. The use of Z wall ties to tie walls made with other than hollow masonry units is permitted.
Manufacturer's Comment: Z wall ties are only allowed in composite (solid) wall construction.
Multiwythe Walls (cavity)
Specified distances between wythes shall not exceed a width of 4.5 in. (114 mm) unless a detailed wall tie analysis is performed.
Wythes of walls designed for noncomposite action shall be connected by wall ties meeting the requirements of composite walls except that when cavity drips are used, the spacing indicated shall be halved or evidence shall be provided to show that their strenght is equivalent to ties without drips, or by adjustable ties. In addition, ties shall be designed to transmit transverse loads from one wythe to the other.
Adjustable ties shall meet the following requirements:
- One tie shall be provided for each 1.77ft2 (0.16 m2) of wall area
- Horizontal and vertical spacing shall not exceed 16 in. (406 mm)
- Adjustable ties shall not be used when misalignment of bed joints from one wythe to the other exceeds 1 1/4 in. (32 mm)
- Maximum clearance between connecting parts of the tie shall be 1/16 in (1.6 mm)
- Pintle ties shall have at least two pintle legs of wire size W2.8 (3/16)