Best anchors for hollow concrete block wall?

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jrcollins

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#293676 7-Feb-2022 16:29

I'm building a workbench in my garage and need to attach a 2x4 to a hollow concrete block wall. The 2x4 will be supporting one side of the workbench.

Can anyone recommend a good fastener to use?

There seems to be quite a wide range of different options but it's not always clear which ones are suitable for hollow block and it seems some can only be used in the solid portion of the block.

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#2863092 7-Feb-2022 17:53

Your going for strength here go for the solid part of the block and use dyna bolts. m10x125mm at about 800mm spacings.

Be best to get a rotary impact drill to get the holes right.

PolicyGuy

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#2863124 7-Feb-2022 18:43

Are you sure it's actually hollow?

I'm not a builder (DIY or for-hire), but the block walls I've watched being put up* had rebar put in them and concrete poured in after every few courses.

* "I love work, I can sit and watch people doing it for hours" :)

josephhinvest

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#2863125 7-Feb-2022 18:54

I’ve used various sizes of these Cobra concrete screws for mounting a clothesline, shelves, a rack for roofbox etc to cinderblock walls. They’ve always been really robust. The pack comes with a correct size masonry bit.

Cheers,
Joseph

eracode

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#2863128 7-Feb-2022 19:02

These masonry anchors were mentioned in another thread here on GZ a couple of weeks ago:

https://www.geekzone.co.nz/forums.asp?forumid=141&topicid=293458&page_no=1#2857199

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jrcollins

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#2863134 7-Feb-2022 19:46

PolicyGuy:

Are you sure it's actually hollow?

I'm not a builder (DIY or for-hire), but the block walls I've watched being put up* had rebar put in them and concrete poured in after every few courses.

* "I love work, I can sit and watch people doing it for hours" :)

That's possible but I mounted a hose reel on the outside of the wall a few months ago and it was definitely hollow where I drilled. I used some Ramset Universal Fasteners which are good for light duty applications but probably not up to supporting a workbench.

https://www.mitre10.co.nz/shop/ramset-universal-wall-anchors-pack-of-20/p/274883

Jase2985

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#2863139 7-Feb-2022 20:26

josephhinvest: I’ve used various sizes of these Cobra concrete screws for mounting a clothesline, shelves, a rack for roofbox etc to cinderblock walls. They’ve always been really robust. The pack comes with a correct size masonry bit.

Cheers,
Joseph

i would use something like this and also some construction adhesive on the back of the 2x4 as well

Jase2985

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#2863140 7-Feb-2022 20:27

PolicyGuy:

Are you sure it's actually hollow?

I'm not a builder (DIY or for-hire), but the block walls I've watched being put up* had rebar put in them and concrete poured in after every few courses.

Depends on what the wall is used for, if its freestanding it might have nothing in it at all.

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jrcollins

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#2863217 7-Feb-2022 22:29

josephhinvest: I’ve used various sizes of these Cobra concrete screws for mounting a clothesline, shelves, a rack for roofbox etc to cinderblock walls. They’ve always been really robust. The pack comes with a correct size masonry bit.

Cheers,
Joseph

It looks like 6mm is the largest size screw which probably isn't strong enough. Ramset has the AngkaScrew which supposedly can be used for anchoring into hollow block but I can't say I like the idea of screwing into concrete.

djtOtago

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#2863220 7-Feb-2022 22:35

If it is hollow, I would bolt it right through the wall.

Jase2985

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#2863309 8-Feb-2022 07:32

jrcollins:

It looks like 6mm is the largest size screw which probably isn't strong enough. Ramset has the AngkaScrew which supposedly can be used for anchoring into hollow block but I can't say I like the idea of screwing into concrete.

6mm is big, and you would just use more. personally i think you would have no issues if you used enough of them. that 10 pack would be fine for 2+m. As mentioned i would also use construction adhesive.

but why don't you make the bench have rear legs which will support the vertical weight on the bench then you only need a couple of fasteners to stop it coming away from the wall.

jrcollins

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#2863525 8-Feb-2022 11:59

Jase2985:

jrcollins:

It looks like 6mm is the largest size screw which probably isn't strong enough. Ramset has the AngkaScrew which supposedly can be used for anchoring into hollow block but I can't say I like the idea of screwing into concrete.

6mm is big, and you would just use more. personally i think you would have no issues if you used enough of them. that 10 pack would be fine for 2+m. As mentioned i would also use construction adhesive.

but why don't you make the bench have rear legs which will support the vertical weight on the bench then you only need a couple of fasteners to stop it coming away from the wall.

Yes, 6mm might be big enough if I use enough of them but maybe not the best solution. Using supports is definitely an option. Thanks for the suggestions.

Jase2985

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#2863529 8-Feb-2022 12:03

big enough for what?

jrcollins

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#2863535 8-Feb-2022 12:17

djtOtago:

If it is hollow, I would bolt it right through the wall.

Yes, it is hollow and I do have access to the other side of the wall. That probably would be the best solution in terms of strength. I could use threaded rods with square washers and maybe have a span of timber on the other side of the wall as well to help spread the load.

eracode

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#2863536 8-Feb-2022 12:22

If 6mm isn’t big enough, there’s these:

https://www.gfcfasteners.co.nz/iccons-thunderbolt-concrete-hex-screw-bolt-m10-x-6

https://www.gfcfasteners.co.nz/tecfi-hwh-concrete-hex-screw-bolt-c1c2-8mm-x-80mm

Bear in mind that the force you’re wanting to resist is primarily a moderate downward-shear force - not so much a horizontal ‘pull out of the wall’ force. It doesn’t need to be over-engineered. IMO a decent number of the 6mm Cobra screws would be plenty strong enough - especially with adhesive.

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rphenix

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#2863667 8-Feb-2022 16:38

I highly recommend regardless of the bolt using chemical anchors this video shows it pretty well. I use a bit of Selleys knead it for small jobs as an alternative instead of plugs as they always seem to come out.

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