How to Choose Anchors and Screws for Mounting Heavy Items
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Work out what the wall is before you pick the fixing
Nearly every heavy thing that comes off a wall comes off months later, long after you have stopped thinking about it, and it is usually because the fixing got matched to the object rather than to the wall it went into. So the first job is working out what you are actually drilling into, and the anchor decision follows on from there.
Knock along the wall with a knuckle and listen, because plasterboard sounds hollow and goes quiet where a stud is sitting behind it, while brick or concrete just sounds solid and a bit unfriendly. If you want to be certain, drill a small pilot hole somewhere that will end up hidden behind whatever you are hanging, and look at what comes back out of it. Plaster dust is white and fine, timber gives you shavings you can see straight away, and masonry gives you grey grit.
Studs in most Australian houses sit at either 450mm or 600mm centres, so once you have found one you can measure across and find the next one without hunting for it all over again.
The fixings, and what each one is actually for
A nylon frame plug is the little ribbed one everybody has in a jar somewhere in the shed, and it belongs in masonry, where it grips by expanding against solid material. It is a picture and curtain rod fixing. Put one in plasterboard with a shelf on it and it will pull straight back out through the sheet and take a lump of the wall with it, which is easily the commonest failure we hear about at the counter.
A butterfly toggle goes into plasterboard and opens out behind the sheet, so the load is spread across a wider patch instead of one small hole. That is your medium weight option, so a small cabinet or a light shelf.
A spring toggle is the heavy version of the same idea, with two steel wings that snap open behind the sheet, and it is what you want for anything genuinely heavy that cannot reach a stud. You do need a bigger hole to get the wings through, and you cannot take the screw all the way back out afterwards without losing the toggle inside the wall, so get your spacing right before you commit.
A hollow wall anchor, which some people call a cavity anchor, crumples up behind the sheet as you tighten it and then stays there as a permanent threaded fixing, so you can unscrew and re-screw into it as often as you like. They are sized by the thickness of the material they are clamping, so we will ask how thick your sheet is before handing you a packet.
Into brick or concrete, a masonry anchor or a screw bolt does the work, and the hole size matters more here than anywhere else, because the expansion against the sides of the hole is the whole mechanism.
And if you can land on a timber stud, do that instead of any of the above, because a decent screw biting into solid pine will out-hold every anchor on this list. An 8 gauge screw long enough to get 35mm or so into the timber is plenty for most things people hang.
The bit that catches people out
Weight ratings on the packaging are worked out for a load hanging straight down against the wall, and a shelf does not load a fixing that way at all. The further the shelf sticks out from the wall, the harder it levers the top fixing outwards, so a 300mm deep shelf pulls on its anchors a good deal harder than a picture of exactly the same weight does. Work on the deep shelf needing a better fixing than the arithmetic suggests, and spread the load over more fixings rather than fewer.
The other one is hole size. Too big and the anchor spins in the hole instead of gripping, too small and you will split the plug forcing it in, so use the drill size printed on the packet rather than the one that looks about right in the drill index.
Do not keep tightening it
Once the fixing has gone tight it is done, and every extra turn after that is either stripping the anchor or crushing the plasterboard around it. If it suddenly goes loose while you are still tightening, it has already let go, and the honest answer then is to move across a bit, put a fresh fixing in and patch the first hole.
Shop related products
- Macsim Spring Toggle 3mm x 75mm. The heavy plasterboard fixing, for anything that cannot reach a stud.
- Macsim Butterfly Toggle 19mm. Medium weight in plasterboard, and cheap enough to use several.
- Nylon Frame Wall Plug 25mm. The masonry plug for pictures and curtain rods.
- Macsim Timber Screws 8-10 x 45mm. What to reach for once you have found the stud.
- Supercraft Torpedo Level. Short enough to sit on a bracket while you mark the holes.
There is a lot more in the fasteners and fixings range than we put online.
Did you know we also stock hollow wall anchors in sizes from 1.5mm right up to 32mm material thickness, plus a vinylester chemical anchor for the solid masonry jobs, and none of those are listed on the website. Give us a ring on (08) 8536 4333 and tell us what the wall is and what is going on it, and we will match the fixing to it.
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I still carry the packet over to the wall with me so I can read the drill size straight off it, because guessing that one never ends well.
Cheers,
Candeece
