Mounting a light to stucco exterior wall

[Abe]

Hi everyone, I'm trying to mount a motion-sensor light to our stucco exterior wall so we can see our key-lock when coming home at night. The problem is we have a stucco exterior and whatever is behind it in the area we are trying to mount is hard metal. I thought there'd be a plywood board and/or a composite wood beam of some kind (it sits on several columns so is a structural beam for sure). I also can't get all the way through it with my metal drill bits. Any thoughts other than a harder drill bit?

[secondcor521]

I think there are special bits for stucco.  Get one of those, and then be prepared to spend some time waiting for the drill bit to cool down.  My first house was stucco and she wanted decorative shutters @ 4 holes per.  Took several hours.

[uniwelder]

When stucco goes on a wood structure, there's usually metal lath (expanded metal mesh) against the plywood surface for extra reinforcement.  How many holes have you tried drilling?  If its just one or two, you might have just unlucky enough to hit the right spot where the metal is.

edited to add--- from what secondcor521 said--- Did you start with a masonry bit and then switch out bits when you hit the metal?  And in between blow the hole out pretty well to avoid dulling the drill bit with cement/sand?

edited to add again--- Is this under the gable end of the roof?  If it was built with trusses, there will be a metal plate, about 8"x8" at the peak.  I had this happen when I put an outdoor light at that location.  If you're trying to dill overhead, you might think you're pushing hard, but not really getting much force against the drill bit.  I ended up just punching through the metal plate with a punch (or sharpened nail) and hammer.

[Fishindude]

Are the walls behind the stucco masonry or wood framed / sheathed?
You will be drilling through the stucco and anchoring to whatever is behind it.

If masonry, you would typically drill with a hammer drill and masonry bit, then use either a Tapcon type threaded fastener or some type of small expansion anchor.

If Wood, just drill through the stucco and metal lath, then stop before you get into the wood.   Then use wood screws of some type to anchor the fixture.
If fixture has much weight to it, you will want your  fasteners to hit a stud or some framing.

[Abe]

Thanks for the recommendations; will try a higher ladder then punching through it and/or switching out the bit (got a new metal drill bit to try). I’m fairly sure there’s no masonry as we had a different part of the exterior redone and it was stucco - metal netting - plywood. After thinking more, maybe  I’m hitting a fastener plate of some sort, between the structural beam and the column. I thought I was high enough to avoid it; but guess not.

[Papa bear]

I’m going to add anything to fishindude post.  But in my area and the buildings in the late 70’s and early 80’s, the stucco was installed over foam and then the wire mesh.  Trying to install anything on it is a pain in the ass.


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