Mending Plates for Stair Treads 1

[UTK_Civil]

My facility has numerous cast metal treads from the 1950s. These treads are starting to fail some with large cracks and some with small cracks. I recently started having a 1/4" aluminum plate added to the treads with small cracks...say less than 2". I have the crack stop drilled and add the plate on top of the existing tread with a bolt extending through both the 1/4" skin, the original tread and angle supports located at each edge of the tread. I recently was questioned on this method as the person was concerned that the 1/4" plate would not hold if the cast tread underneath failed catastrophically. Does anyone have any experience with this type of situation?

 

[MotorCity]

I have not encountered your particular situation, but can offer the following:

1. If it were me, I'd recommend replacing the treads rather than applying a band aid. Stairs and their components can be
critical to life safety, whether intended for egress or not.

2. When you say "cast metal", I assume they are cast aluminum and are compatible with your aluminum repair plates.
Otherwise I'd have galvanic corrosion concerns.

3. Any material that protrudes above a tread or tread nosing creates a potential hazard and may even be prohibited by your local
code. I would never recommend a stair repair that included bolts, plates, welds, etc. that protrude above the walking surface

4. If a tread were to fail, catastrophically or otherwise, whether or not the repair plate survives is a moot point.

 

[JLNJ]

I agree with Motor City.

To pile on - if you simply cover up the problem, then you have no way of seeing if the original tread is getting worse. If the original tread breaks, what is the aluminum connected to? The broken tread? That doesn't seem sensible. Lastly, adding to the tread creates a taller tread in that first step. Building codes frown upon varying tread heights in a run because in an emergency you don't want to be surprised by any unusual stair geometry.

Stairs are inherently dangerous. Treat stair design/modification with due caution.