I have a number of large aluminium signs (4ft x 3ft) that I need to fix flush to pre-cast concrete slabs. Ideally I would like the fixings to be invisible rather than screw heads which will be visible and have been trying to source some kind of solution to no avail - Can anyone advise please?
Many thanks

  • Counter sunk screws are the normal way to attach a plate with the heads flush. This requires a bit that makes a tapered hole the screw head sits in like this with this kind of screw that one was for wood but there are ones for cement available at most home stores
    – Ed Beal
    Oct 24, 2016 at 9:57

1 Answer 1


I would try a construction glue in a caulking-gun

enter image description here
Random example from Internet, any product with same characteristics will do

  • Waterproof: Can be used in interior or exterior applications
  • Versatile: For use on wood, metal, plastic, foam, mirror, concrete and brick

I've used a similar sort of adhesive to attach small plastic signs to rough granite, with mixed success. Some lessons -

  • You need the surfaces to be clean, dry and free from dust or loose debris.
  • If the back of the sign is very smooth, it might be worth experimenting with roughening it with sandpaper. This may depend on the specifiic adhesive.
  • When fixing signs on a vertical surface, I found it best to support the sign until the adhesive sets. I fabricated a temporary support using scrap wood and other materials.
  • +1 Just be sure the concrete is clean, dry, and any dust has been removed.
    – bib
    Oct 24, 2016 at 12:12
  • @bib: good point thanks, I'll elaborate the answer a bit. Oct 24, 2016 at 12:28

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