Hi, We're looking to screw metal house numbers into this rock. It's Sydney sandstone.
What would you recommend to fix into this rock?
Thanks for looking.
Hello @akalalouie
Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about sandstone.
Sydney sandstone is relatively soft and workable, but it can also flake or crumble if fixings expand too aggressively. Because of this, it’s best to use a fixing method that grips securely without putting too much expansion pressure on the stone. The most common and reliable approach for installing metal house numbers is to use a nylon masonry wall plug with a stainless-steel screw.
To do this, drill a hole using a masonry bit that matches the size of the wall plug (typically around 6–8 mm). Drill slowly with light pressure to avoid blowing out the sandstone. Insert the nylon plug into the hole, then drive a 316 stainless steel screw through the house number into the plug. Stainless steel is recommended for outdoor use, especially in coastal environments, because it prevents rust staining on the sandstone.
If the numbers are designed to stand off from the wall (floating style), a chemical anchor with stainless threaded rod is often the most professional solution. In this method, you drill the hole, blow out the dust, inject a chemical anchor adhesive such as Ramset 300ml Chemset UltraFix Plus or Sika AnchorFix-3001 Chemical Anchor, and insert a short length of stainless threaded rod (typically M5 or M6). Once the adhesive cures, the number mounts onto the rod, giving a clean floating appearance. This method is extremely strong and avoids expansion pressure in the sandstone.
Another option is to use masonry screws that drive directly into the stone, such as Ramset AnkaScrew Masonry Anchor. These are quick to install because they don’t require a wall plug, but they can place slightly more stress on the sandstone and can be harder to reposition if needed.
For most house number installations on sandstone, the simplest and safest approach is to drill with a 6 mm masonry bit, insert a 6 mm nylon wall plug, and use a 40–50 mm 316 stainless steel screw. When drilling into Sydney sandstone, it’s best to start drilling without hammer mode and only use a light drilling action. Keep holes at least about 25 mm away from edges and avoid overtightening screws, since sandstone can strip easily.
Please remember to wear personal protection such as gloves, goggles and a mask when working on your project.
If you need further assistance, please let us know.
Eric
