Whats the best way to attach an outside light to a brick wall?
You can use wall anchors. Drill holes in the wall using the light or new mounting bracket as a template. Use a masonry bit preferably in a hammer drill . It’s a light fixture so the plastic conical anchors that you hammer in will hold it unless it’s a very heavy light.after you mount the light base seal around the wires in the hole with silicone caulk. I am assuming the light has a wiring junction box because you can’t have a connection outside a box.
