Will 1/4" TapCons hold a 72" window box?

Question

Afternoon,

I purchased a 72" window box to hang under a window that is just under 77" in length. The box itself is fiberglass and is 33lbs fully assembled without plants and soil. With plants and soil it has a bit of weight to it. Under 100lbs but still pretty heavy. The exterior to my home is stucco and underneath of that is brick from the original build. (The house was remodeled in 2018) There are no specifications in the window box's manual that imply what size screws are needed to hang this item. It just states that if you're hanging on brick or concrete to use masonry screws instead of the provided manufacture screws. There are four brackets meant to be spaced at least 14" apart included with the box. They allow two screws per bracket.

So my question, will 3" TapCons with 1/4" diameter hold my window box securely without fear of failure?

Thanks in advance.

Answer 1

It should be fine.

Given 100lbs, 4 brackets means 25lbs per bracket. Tapcon 1/4" have a shear strength of 620lbs, so the screws themselves will not fail and 3" should be plenty to get past the stucco and bite into the brick/masonry.

Given an exterior penetration, using silicon or a comparable caulking on the shanks/holes might be advisable to prevent water intrusion.