Walls – Can’t drill into exterior walls for screw anchors. Why not

drillwalls

I'm trying to install an outdoor motion triggered light. I'm trying to drill holes for anchor inserts and I can drill through past about 1/2" in some places.

Please see the picture. You'll see a series of holes in a grid pattern. Some of it was from marking the mounting holes and some of them are discovery holes.
I was trying to see if there are other places that are easier to drill through.

Do I need special bits? I'm using a generic drill bit. Ive had these forever and they've worked for all purposes until now. I'm also using a battery powered drill.

What am I hitting? Am I drilling into metal? It seems like something super hard. It is some sort of metal bracing? Or am I just in a super reinforced area of the house? It's basically where in a corner of the house.
I didn't notice any concrete or bricks when I was exploring the attic. This house was built in 1939. Am I just hitting some really dense wood?

I also have at attic. See second picture. Maybe what I'm hitting is the "floor" of the attic?

I've also just tried to drill on the wall that is perpendicular to it. I've also moved up a foot or so (maybe clearing the attic floor) and also in 5 feet from the corner.

drilling attempts
side of house showing attic level

Best Answer

Hitting something super-hard means don't drill there.

Normally pipes and electrical cables are run far from the edge and close to the center of studs. This is so you can safely drill 1-1/2" onto any wall's skin surface to install screws, anchors, etc.

When it is necessary to place electrical wires or pipes just under the skin surface, they are required to put steel plates there as guards, to prevent someone from drilling onto the pipe or electrical wire.

The idea is the person drilling will hit an unexpectedly hard surface, and think "this is probably one of those".