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In my lounge I have purchased a solid oak shelf to go above my wood burning stove. The shelf has come with this type of fitting.

enter image description here

The issue I have is that I don't know how to fasten these due to the makeup of the wall. The construction working from outside to inside is: Solid external wall, 3x2 timbers fastened to the masonry, plasterboard then screwed into these timbers with insulation between the timbers. The length of the fittings provided are longer than the depth of the 3x2 battens, meaning about 20mm of the screw will need to go past the battens into the masonry behind, but how do I drill into the masonry to accommodate the screw head without making the hole in the timber too large for the screw to grip onto?

The screws themselves are 3 inches/70mm long. The studs/battens to screw into are only 1.75 inches/45mm thick.

I'm a bit stuck and would appreciate advice.

Here is an image of the studs/battens:

studs

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    That is a floating shelf fastener—the threaded part threads into either the plastic anchor (not good) or a stud (good), and the shelf (which has bores in the back edge) slides onto the post of the fastener. It looks like the threaded part only needs to penetrate the wall 60mm tops, which is less than 2". Ideally, you arrange the shelf so that the anchor hits at least one stud (preferably more). Can you provide details of the shelf?
    – Huesmann
    Commented Dec 14, 2023 at 14:14
  • @the_slug your "shelf" (mantel) looks wide enough for you to be able to hit multiple studs. Do you know the stud (batten) spacing? Are your battens arranged with the short edge against the plasterboard, or the long edge?
    – Huesmann
    Commented Dec 14, 2023 at 14:29
  • @Huesmann Unfortunately the building regulations in the UK state that you cannot have combustibles a certain distance from a heat source (My wood burner) so there are literally no studs other than a single noggin for me to attach to. Long edge is against the plasterboard, so just under 3 inches wide.
    – the_slug
    Commented Dec 14, 2023 at 14:36
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    When you write "The screws themselves are 3 inches/70mm long", are you referring to the length of the threaded section or the length of the entire screw?
    – brhans
    Commented Dec 14, 2023 at 15:12
  • @brhans The threaded section, and the small non-threaded section that connects to the little grub that goes inside the shelf itself. Everything up to the grub should be inside the wall.
    – the_slug
    Commented Dec 14, 2023 at 15:18

1 Answer 1

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That is a bit of a head-scratcher. I have two potential solutions. You'll need to investigate the first to see if it's viable.

  1. Shorten the screw. Properly piloted, 45mm of thread is plenty for any reasonable shelf load. Use a hack saw to cut them off at that depth and file or grind a blunt point to help with insertion. Pilot to just under the inner thread (local shank) diameter.

  2. If that doesn't seem to provide enough hold, drill for anchors in the masonry, insert them, then backfill the wood with a dowel and good glue. Finally re-drill through the dowel as in option 1 for the screw threads. Now you theoretically have hold in both the wood and the masonry.

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  • @Tetsujin, I think your answer was appropriate now that we have more information. Please consider undeleting.
    – isherwood
    Commented Dec 14, 2023 at 15:06
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    Thank you. I will attempt #1 first as new screws are cheap and it seems like the most straight forward. I will drill a small pilot hole first, then I will screw in about half way so there is a "channel" in the wood to work with. Then I'll back the screw out, take a hacksaw to it and remove the excess, then I'll screw it back in and hopefully the aforementioned channel helps the remainder of the screw guide itself in and bite into the wood sufficiently.
    – the_slug
    Commented Dec 14, 2023 at 15:17

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