Bond beams are commonly specified in partition walls as a best practice to ensure safety and provide an adequate support reaction with the rest of the structure. The purpose of this page is offer guidance and discussion regarding how these are specified in nonloadbearing partition walls.
This page is part of a larger series of specification examples meant to highlight cases where vague or poorly written specifications have lead to issues on masonry jobs across Canada.
The information contained here is intended to serve as educational content for designers, specifiers, or contractors. It is not to be relied upon for formal technical advice, as masonry projects may have details and considerations that are unique to a particular project and may be beyond the scope of the content of this page.
How the specification typically appears:
X.Y Provide 200 mm deep bond beams reinforced with 2-15M top and bottom at the tops of all walls and at the bottom of interior partition walls and at 3,600 mm vertical spacing. Use special bond beam units to provide continuity of horizontal reinforcement. Lap splice 800 mm minimum. Provide corner bars at wall intersections.
Discussion points to consider when specifying horizontal steel in partition walls:
This specification is poorly written due to conflicts with typical masonry design and reinforcing schemes that will be incompatible with conventional construction techniques. This may lead to problematic long-term structural performance. Three main issues are identified below:
1. Congestion of steel at lap splice location
Requiring a total of 4-15M bars within a 200 mm (single-course) bond beam will likely not satisfy clear spacing requirements of the CSA A371-14. This is a high concentration of reinforcement for a single masonry unit. In general, it is preferable to use a single reinforcing bar (up to two are possible for larger units) per course (horizontally) or per cell (vertically). The presence of lap splices, variable unit geometry, and mis-alignment of unit webs in masonry construction are some reasons why steel congestion such as this should be avoided. There is a high probability that there will be issues with grouting and possibly long-term structural performance issues when the CSA S304-14 and CSA A371-14 requirements for the placement and detailing of reinforcement are not followed.
2. Potentially difficult to construct as specified
Detailing reinforcing bars and grouting those units in the top course of a partition wall constructed beneath existing structural elements (such as concrete floors or steel beams) is challenging. Concentrating large quantities of reinforcement at that level will only complicate matters. It is generally preferable within masonry construction to avoid multiple reinforcing bars within a single course (or cell) at a wide spacing (3,600 mm) and instead opt for a single reinforcing bar placed at a closer interval. An alternative and preferable method for strengthening the top of partition walls is to grout the course second from the top course and only grout the cells in the top course where the where the vertical reinforcing bars are located. These grouted cells must then align with the lateral supports affixed to the structural component above the wall. This allows for better access for masons to install the reinforcing steel and grout which will generally lead to better workmanship and performance.
3. Ambiguity on where this might be applied
The specification refers to both “all walls” and “interior partition walls” leaving it ambiguous as to which elements the different parts of the specification is intended for.
It can be observed that a vertical spacing of 3,600 mm for horizontal reinforcement does not conform to the maximum spacing requirements of the CSA S304-14 for horizontal reinforcement resisting in-plane shear forces. It is also important to mention that the majority of partition walls are not intended to receive in-plane loads or act as a member of the lateral load resisting system of a building. As a result, beams along the height of partition walls are seldom required from a structural perspective.
There are other reasons for requiring bond beams in masonry walls aside from resisting in-plane flexural or shear stresses, such as meeting anchorage or bearing requirements, as well as for crack control. In partition walls, bond beams are often required at the top where support brackets are located. However, designers are reminded that if reinforcement is intended to resist loads then the requirements for reinforcement masonry in CSA S304-14 (10.15) must also be followed. Furthermore, if the need for the bond beam to facilitate prescriptive requirements is not related to resisting loads, then a single 15M bar will suffice.
Suggested changes to the specification:
X.Y. Bond beams in partition walls:
X.Y.a Provide bond beams at the following locations within partition walls: the first course of masonry, the course of masonry located immediately below the top course of masonry. Bond beams shall be 1-course deep (200 mm) and reinforced with 1-15M reinforcing bar.
X.Y.b Special bond beam units with reduced webs, saw cut stretcher units with reduced webs, or U-lintel units with saw cut or otherwise notched bottom faces shall be used in construction of the bond beams in partition walls to permit continuity of vertical reinforcement and grout.
X.Y.c Partition walls shall be grouted only in cells where vertical reinforcement is present and in courses where bond beams are located.
X.Y.d Lap splices, when required, for vertical and horizontal reinforcing bars consisting of single 15M reinforcing bars shall be no less than 800 mm.
X.Y.e Vertical reinforcing bars in the partition walls shall be located at the ends of the partition walls, at locations adjacent to intersecting walls, at wall corners, on all sides of openings over 1,200 mm long , and at spacings no more than 2,400 mm horizontally on centre.
X.Y.f Vertical reinforcing bars, and grouting of those cells containing vertical reinforcement, shall extend to the top of the wall. Partition anchors shall be positioned only at locations where vertical reinforcing bars are present.
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