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I want to fasten some boards to my basement walls to act as mounting backers. The walls are natural stone, Diabase if that's important. They can be damp at times. The boards will bear some weight, I'll be hanging stuff on them, and using plastic spacers to prevent the boards touching the walls and to account for the uneven stone surface.

Can I use Tapcon™ concrete screws? Their docs list all kinds of masonry but not stone. That would be ideal because without anchors I don't have to drill large holes.

If I need to use anchors can I use use metal lag shields? Regular plastic masonry anchors? Again, everywhere I see specs, they spec all kinds of masonry but not stone.

I have hung some lightweight things on these walls with plastic anchors, but that proves nothing, there's no test of how effective the anchors are when all they are holding is EG a light switch. A few heavier things were hung by pros using powder-driven fasteners. I'd go there if it's my only option, I guess that would be fun if I can learn to do it safely.

isherwood
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jay613
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6 Answers6

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You should consider using a chemical stud anchor. If you've ever been to something built inside a cave you've probably seen these.

A chemical stud uses an epoxy to hold a fastener into the material. They're great for natural stone because they don't rely on wedge points within material and the epoxy should fill in the void completely to prevent water intrusion.

The fasteners will be permanently attached to the stone but it will likely be a threaded rod which allows you to readily remove whatever you attached to it and also to finely adjust the spacing away from the uneven surface.

Matthew
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Here's a partial answer: Tapcon's customer support answered my question saying that they are not for use in stone, only concrete, block and brick.

jay613
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Tapcon™ screws, as their name implies, work by cutting (tapping) a thread into a predrilled hole in concrete. I wouldn't expect that to work well, if at all, in a less granular material, but I have no experience with diabase; on average it seems to be about one Mohs step harder than (equally average) concrete. Try it and see?

If you can drill a hole at all, I'd consider either one of the expanding anchor types -- including traditional lead anchors-- where driving the screw squashes the anchor firmly against its surroundings, or one of the epoxy bolt setting systems.

Exactly what makes sense will depend on what stresses you expect this to take, in which directions.

keshlam
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If they are available in your area, Fischer has some universal plugs:

https://www.fischer-international.com/en/products/standard-fixings/plastic-fixings/universal-plug-ux

which are specified as suitable for natural stone too (see the list of building materials in that page under "Application and Approval").

LorenzoDonati4Ukraine-OnStrike
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Drive Pin Anchors

aka Hammer Drive Pin Anchor Set

I've never been able to shear them, but must be drilled out to remove.

enter image description here

From https://www.grainger.com/product/11K342

Criggie
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BZZZzzz...
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I’ve used these lead anchor drive pins before. They were excellent compared to those tapcon when I was trying to go into cinderblock. What I liked about the hammer based ones was they never loosened up I had them installed with some cabinets that had a flat back and use them to attach the cabinets to the wall Through the wood frame. In the past when I’ve used the tap con into Concrete block, eventually they rushed and the device I had mounted to the wall which just fall to the floor after a few years. I was surprised to see this because they had that blue coating on them, which I thought was supposed to prevent rust .

Ed G
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