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I've got three exterior steps made of natural sandstone. They are 6 ft wide, and 10" thick. I need to anchor a metal handrailing to them. The railing has two feet: 1/4" metal plates with 3/8" holes drilled 10" apart.

I original thought of using cammed anchors for rock climbing, but I'm worried that the force of the cam will crack my stone steps. I then thought of drilling out a hole, filling it with epoxy, and then putting some 3/8" threaded stock into the hole and letting it dry. This would provide studs on which to bolt the stairs.

If epoxy is the way to go, is there a specific product that is recommended?

How is this usually done?

  • Cam anchors are (a) expensive and (b) designed to hold under tension but release easily. Probably not the right answer for this application. – keshlam Nov 10 '14 at 22:59
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Something for your consideration, if you can have the railing modified or corrected. Don't mount it to the stairs at all if you absolutely don't need to, which you don't. If the railing hit's the house & overruns the bottom step or is long enough. Attach it to the building's exterior wall & the ground or pavement at the bottom of the stairs.

Bridging the stairs is one of the proper ways to do a short railing. The other way is for stairs that closely match the width of the door. The railing only stands next to the stairs but is attached to & into the ground's pavement.

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Normally this is done by drilling an oversized hole, filling it with mortar and inserting a threaded anchor. The modern way to do things is to use what is called a "drop in anchor". This is an expanding anchor, kind of like a dry wall anchor. You drill the hole to size, drop in the anchor (tap it in with a hammer actually). When the bolt is screwed in, the anchor expands locking the bolt in place (hopefully). The fit needs to be snug. The mortar solutions will be a lot stronger, but more time consuming because you have to mix mortar and wait for it to set.

One of the problems with using a mortar anchor is simply finding one that matches your bolt. You can use a lag shield anchor as one way around this. Another tricky trick is to use nuts. Thread a whole bunch of nuts onto the screws until you have a solid column of nuts. Make sure the nut at the bottom has a little extra space, even glue an extra nut for extra space. Pour the mortar and then put the whole assembly, railing, bolts, nuts and all in place. Finally tighten the bolts.

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    I've seen the drop in anchors before. If it was concrete I'd definitely do it that way, but with the natural stone I'm worried about fracturing. It's only sandstone. – svh160 Nov 11 '14 at 2:38

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