To be honest, I don't recall the exact specs-- this project was done years ago. I do remember core drilling into the concrete with pre-drilled steel tubing, and then screwing the bench slats to the tubing through the pre-drilled holes from below. I don't recall the steel guage or size unfortunately. It was time consuming, if I remember correctly. Best, Justin

Thanks Justin, very informative. I feared it was something carefully engineered like that, rather than something off-the-shelf I could secure to a normal brick boundary wall. Thanks for the insight.