How can I mount a mailbox on a stucco wall?

Question

Been searching around and I have more questions than answers. I'm not sure what kind of stucco it is, but it is very smooth. The mailbox is a little heavier than you might expect (maybe 10-15 lbs).

Before doing any research I figured I would drill with a masonry bit and use some sort of anchor intended for stucco, and that would be it. Unfortunately I am finding lots of contradictory information:

• some things say to use a plastic anchor, some say never to
• some say that the following photo is a stucco anchor, while some say it's a drywall anchor:
• some say that I have to have a particular type of stucco
• searching for stucco anchors at Home Depot, for example, just brings up different types of screws meant for concrete (some of which actually say "anchor" right on the package even though they are screws and not anchors - so maybe anchor doesn't mean what I think it does?)
• some things say to use some kind of silicon sealant in the hole I drill, others make no mention of this

I did experiment a bit in an inconspicuous location and using a cement screw didn't work well at all (I drilled a hole with the bit size the instructions said to use, and the screw was completely loose). Using the drywall (?) anchor above seemed to be very secure but it really chewed up the stucco as I was screwing it in (I drilled a hole first but just guessed at the size).

What's the best approach here and why is there so much contradictory information out there?

Answer 1

10-15 pounds seem heavy for a mailbox but even plastic drywall anchors are rated higher than that for so I don't think the weight is going to be a problem.

That's a drywall anchor. A lead anchor look similar and is typically used on brick siding but depending on depth of stucco it is possibly you could rely on a lead anchor in stucco.

What you really want is to mount the mail box through the stucco to the sheathing that is behind the stucco. Depending on your wall assembly details - year of construction / climate - the sheathing can be 1/2" away from the surface of your stucco or 1 3/4"+ away or anything in between.

The sheathing is going to be wood so really all you need is to pilot through the stucco until you reach the wood. You should choose some corrosion resistant fasteners - deck screws #8 would likely be good. Opt for 1/2" + thickness of wall before shealthing plus depth required to mount mail box (if metal 1/8" is probably fine). If you've already drilled through the stucco then you can probably note at what depth the wood starts as the drill will behave differently as it goes through different material. If you were using a hammer drill with a masonary bit that bit will likely stop when you hit wood. This assumes a concrete type stucco and not an acrylic stucco which I haven't dealt with before.

It wouldn't hurt to fill the hole with caulking before mounting the mailbox to the stucco to prevent any water ingress.

Good luck.