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#35797 03/21/04 05:08 PM
Joined: Mar 2001
Posts: 2,056
Redsy Offline OP
In many older areas, stone foundations with crumbling mortar presents a problem in mounting equipment.
Has anyone ever used Tapcon screws in stone?

#35798 03/21/04 10:20 PM
Joined: Dec 2002
Posts: 228
I have used them in brick, concrete block and mortar. The brick doesn't always hold too well, the bit seems to not drill quite right and your hole ends up being a bit too big, not to mention a pain to drive the screw in.

#35799 03/22/04 09:09 AM
Joined: Oct 2001
Posts: 597
I've done my share of work in late 1800s vintage dwellings. The foundations will commonly be 18" to 24" limestone that was set with low portland mortar. Occasionally, I'll have to attach to poured walls with large (fist sized) sedimentary stone fill.

I've found that the stone generally grinds down the thread of the concrete screw into a conical shape. The thread at the tip of the screw gets ground away the most.

The screw will grip so hard that the shaft will twist off at the head. Backing the screw out a turn and setting it two turns, repeatedly, will help to get it in without breaking the shaft. Then removing the screw and chucking it, and inserting a fresh one, will complete the installation.

Fortunately, I've had little granite to have to deal with in my area.

Al Hildenbrand
#35800 03/22/04 12:02 PM
Joined: Mar 2001
Posts: 2,056
Redsy Offline OP
Thanks, guys. You might have saved me some aggravation!
I have been searching for an alternative to fabricating 2 x 4 support "struts" off of the joists and mounting plywood to them.
Any other ideas?

#35801 03/22/04 06:59 PM
Joined: Dec 2001
Posts: 300
I love these anchors:

[Linked Image from]

Ramset makes them and so do others.

Just drill a 1/4" hole and a couple of hammer hits (sometimes with big drift punch if you're working inside a box) sets tha anchor.

And you can hang a box by one anchor and drill the holes for the others right through the back of the box. Don't have to measure, mark, remove, drill, rehang to find you drilled the hole in the wrong place.

#35802 03/25/04 04:41 PM
Joined: Mar 2004
Posts: 10
I don't do much resi, but an old time resi guy I worked for when I did my resi stint, showed me how to mount SE cable using wood dowels. Drill a hole, hammer in a good solid wood dowel and than screw to it. Seemed to wrk pretty well. Do not know personaly how long it will last (wood rot) but this guy was pretty anal and seemed confident in this.
Hope this helps.
I have used Tapcons to no avail. Have had the Hilti rep evn demonstrate it using the 3/16" bit and than screw in the Tapcon. Tap con will never tighten. Might be good for something very light, but conduit, boxes or SE I think is risky. I think the best thing for stone would be the wood. But any other suggestions I would be interested in learning

[This message has been edited by ChrisDeckard (edited 03-25-2004).]

#35803 03/25/04 04:50 PM
Joined: Jan 2003
Posts: 4,391
110.13 Mounting and Cooling of Equipment.

(A) Mounting.
Electrical equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry, concrete, plaster, or similar materials shall not be used.

Bob Badger
Construction & Maintenance Electrician
#35804 03/25/04 06:21 PM
Joined: Mar 2004
Posts: 10
Thank you

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