To mount a 35lb wood framed antique mirror, I got 4" long concrete screws on recommendation from someone. They're 200lb load screws. The wall is above a fireplace and has half an inch of plaster followed underneath by concrete or possibly brick (we're not sure). Looked more like concrete, not really red.

So that's about 3" that are in the concrete, 5/8" of that is only in plaster and there's about a 1/4" sticking out and kind of hovering in a slightly oversized drill hole. I've included photos.

Should I fill in those gaps in the drill hole with spackle? Something else? Or just leave it because those screws are secure enough to hold the mirror? Left screw Right screw

  • How many screws are you planning? Are these on a. Wire or around the frame? Tapcon screws will hold but I would be concerned with a single point on a wire
    – Ed Beal
    Commented Jul 25, 2017 at 2:24
  • Two screws on the wall. The mirror has thick plastic shielded cabling on the back fastened with D-loops to the wooden frame. Commented Jul 25, 2017 at 2:26
  • Why is the pre-drill hole oversized and how deep did you pre-drill?
    – Tyson
    Commented Jul 25, 2017 at 12:31
  • It's how it ended up from drilling. Probably wobbled just a bit. I predrilled enough so that this 1/4" would stick out for hanging. With the bit the screws came with. They locked in tight when I screwed them in. Commented Jul 25, 2017 at 14:53

1 Answer 1


Those apear to be Tapcon type screws with 2 there should be no problem supporting the load. I would probably add a washer to each screw so the wire cannot jump off the head if the mirror is adjusted. I would not worry about trying to fill the hole around the shaft of the screw it will support the load and if filled when removing the screw at a later date it may break the plaster.

  • They are essentially Tapcon, they're called Cobra. We don't have Tapcon in Canada, I looked. I like the washer idea but how do I get them on there? I thought once concrete screws were in, removing them compromised the hole? And I'd need to remove them to add a washer now. Guess I blew it, do I need two new holes? Commented Jul 25, 2017 at 14:56
  • I would probably see how it holds depending on the size of the wire it may be ok.
    – Ed Beal
    Commented Jul 25, 2017 at 16:53
  • That screw head will never snap off, will it? Commented Jul 26, 2017 at 14:31
  • Not worried about the head, if the mirror gets moved or a sizemic event the wire jumping the head.
    – Ed Beal
    Commented Jul 26, 2017 at 18:44
  • 1
    I'm going to take some wide thin washers I have, make a single cut into the center from the outside and slip that onto the screw so that the cable sits between the washer and the wall. Just so it's there. We're unlikely to ever have any seismic activity here in Quebec but, you know, you go clean a cobweb, you forget how loose it sits on the screw, it's worth it to put something up there. Commented Jul 27, 2017 at 2:02

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