You've seen the steel or cast iron plates on the faces of brick walls downtown. Sometimes they're stars or diamonds, sometimes plain squares. They are there because they serve an essential purpose. They are part of an affordable solution to strengthening our brick buildings for future generations and satisfy IEBC Code requirements.
Think of them as anchors. Like a ship's anchor that keeps the boat from floating away, these anchors keep the exterior walls of a building from leaning and eventually falling away from the floors and roof.
When brick buildings were constructed years ago, the floor joists were supported at each end by inserting them into pockets in the brick walls. These joist ends were stabilized by friction and mortar acting as glue; often no mechanical connections were provided. The brick walls thus carry the cumulative weight of all the building's floors and roof. On the other two sides of the building, typically the front and back, the joists run parallel to the walls and may not even be in contact with them.
Fast forward 100+ years: the old lime mortar "glue" is failing. The walls have started to shift, bow, or lean due to several actions, including temperature differentials, moisture degradation, wind events, and eccentric loading. The hard truth is that our old brick buildings in Memphis are "time bombs" when it comes to the risk of collapse because the bricks and the mortar are slowly breaking down & disintegrating. It typically takes 150 years for the old archaic brick to turn to clay dust and the lime mortar to turn to loose sand. However, this process is greatly accelerated by high moisture at the foundations and tops of walls. Evidence of this is something we commonly see on inspections of old brick buildings.
This is where the anchors come in. The steel plates you see are structural retaining washer plates secured to steel rods that fasten to floor joists or beams inside the building. The rods go through the brick walls, essentially "tying" the floors to the walls.
This connection restrains the wall's lateral movement and ensures that the joists and beams remain fully seated in their pockets. Thus improving load transfer between floors and walls in all three axes. And relieving the aging brick walls from destabilizing eccentricities. Since wall stability failure is most commonly the cause of collapse for this building type, this repair significantly extends the useful life and safety of the building.
Think of this as the "weakest link" or "low-hanging fruit" approach to structural strengthening. It can give our precious historic urban buildings another generation or two of useful service life. This anchoring should usually be installed on all four sides of a building, on each floor and roof. And yes, it is also a relatively low-cost and effective way to provide seismic stabilization.
This is often the first step of a multi-pronged strategy to preserve a building of this type. But even used alone, it can, in some cases, be an economical way to keep these buildings safe and serviceable for another generation or two. And this practical method has stood the test of time. From its roots in ancient Rome, tie rods and anchor plates have been trusted to reinforce masonry structures. They have become a standard tool in restoration because they are dependable and practical.
And most local municipalities have adopted the 2021 IEBC as the Building Code for Existing Buildings, which requires URM Wall Anchors for many adaptive reuse projects.
If you have an aging brick building and would like to preserve or adapt it for a new use, ask us about an assessment to determine if these anchors are part of the solution.
And get ahead of the game!
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