68 | Masonry Design
Bonding with
Masonry
David Biggs, PE, SE
Technical Talk
I hope you had a good summer! Masonry
construction has been very active and brought
about some new questions.
Q: On a recent project, we used loadbearing
CMU with brick veneer as a cavity wall. The interior
walls were mostly CMU also. For aesthetic
purposes, we located the exterior brick expansion
joints on our architectural elevations. However,
the mason contractor disagreed with our specification
that required them to locate the movement
(control) joints in all the CMU walls including the
exterior backup walls. Why is our specification a
problem for the contractor?
A: Unfortunately, this is a common source of
conflict on some projects.
Just as you did, other architects have provided
the exterior joint locations for aesthetic reasons.
While aesthetics are important, there are other
reasons for locating the joints that are codebased.
Let’s start by reviewing the designer’s
responsibility as stated in TMS 402-13, Building
Code for Masonry Structures which is the
referenced masonry standard in building codes.
“4.1.5 Other effects
Consideration shall be given to effects of forces
and deformations due to prestressing, vibrations,
impact, shrinkage, expansion, temperature
changes, creep, unequal settlement of supports,
and differential movement.” Without specifically
saying the designer must show the joint layout, it
is clear the designer must accommodate shrinkage,
expansion and differential movement.
In TMS 602-13, Specification for Masonry Structures,
Article 3.3.D.6, the contractor is to “Install
movement joints.” It does not require that the
contractor provide the layout and design of the
joints.
Later in the Mandatory Requirements
Checklist, we see more specific guidance to
designers which states:
Section/Part/Article
“3.3 D.6 Movement joints
Notes to the Architect/Engineer
Indicate type and location of movement joints on
the project drawings.”
The checklist is also very clear that the movements
joints are to be on the drawings, not in the
specifications.
So, it seems that both the design and layout of
movement joints are totally a designer’s responsibility.
Not so fast! Here’s where the confusion
starts. TMS 602 is a specification that designer’s
may choose to reference directly or modify. Thus,
it is not uncommon for architects to insert specific
criteria into their project specifications that might
not already be in TMS 602. One of the modifications
many architects have used is similar
to yours, and requires the mason contractor to
locate the movement joints.
This is where the conflict develops! While the
designer can modify the specifications, they can’t
do so and modify the code itself. By mandating
the contractor select the joint locations, the
designer is not meeting the code since it’s the
designer who needs to accommodate shrinkage,
expansion and differential movement based upon
Section 4.1.5. Therefore, my interpretation of the