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This house was built in the mid 1950s. I assume the rock wall was built at the same time. It has an old railing that is not attached anymore and needs to be replaced. My current plan is to cut off the old railing and build a wooden post and cable railing.

enter image description here

This is just an example of what I'm trying to accomplish.

My issue is that I'm not sure how to anchor the posts to the wall.

enter image description here Here is the rock wall.

enter image description here You can see that the mortar at the top isn't in the greatest of shape.

enter image description here The span is about 16 feet total.

The current railing is secured via some odd pieces of rebar and having some of the metal posts mortared in to the wall. The rebar has detached in some places and some of the posts have just broken off, leaving the whole thing just flopping around.

My original plan was to cut the old railing off and get something like these post bases and anchor them directly to the wall using these bolt wedge anchors with some washers or something to shim it to keep the whole thing level. I've since realized that bolt wedge anchors are probably not a good idea on these stones. I'm also worried that using a hammer drill on this wall will simply knock the rocks loose.

I think I've got a handle on how to build out the railing if I can figure out how to mount the posts to the wall. That's my concern right now. Thanks.

  • Have you considered the option of installing the new railing just inside the existing rock wall top curb? You could then rent a core drill to make suitable holes in the concrete slab adjacent to the rock wall into which you can embed posts in concrete. Such process would be much stronger than trying to use surface mounted box brackets and look better as well. – Michael Karas Sep 20 '17 at 13:07
  • The problem with that is that there is a door right up against the edge of the wall. The post on that end would be right in front of the entryway. – Ryan Elkins Sep 20 '17 at 13:32
  • How about a wooden planter with a short (2'?) railing along the back? That way it'd become self supporting and not require any structural integration. If you don't want to go the planter route, it could be a bench or the like. Maybe add a couple bolts to the bottom and anchor to the concrete slab for extra security. – DA01 Sep 26 '17 at 1:17
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Cut the existing fence out in pieces, preserving as many of its original vertical support posts as you can. Instead of solid 6x6 lumber, use four pieces of 2x4 lumber in a square, and secure them tightly to the original posts. You might also be able to design a special pentagonal support this way that would work well in the middle corner of your wall.

Or if the original support posts are hollow below grade (which is a long shot), cut them off flush, and embed new threaded rod inside them with epoxy.

Anther option is to accept that you're going to damage the wall when putting in new fasteners, and also plan to add a new cap layer to the wall that would cover up that damage. Avoid using high impact hammering, try to find a bit that can grind instead, and use plenty of water to wash it out while drilling.

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  1. If you can get access to a "core drill" - the kind of thing that will make 2- or 3-inch holes in concrete - then you can set some threaded rod with nuts and washers in new-poured concrete. Then drill a hole up the wooden post, put the post on a gasket of some kind (for moisture control), and drill in from the side of the post to provide a way to install a top-nut and washer. This would make a super-strong connection, with no visible supports. (Put the hole for the nut facing away from view, and back-fill it with scrap material and putty.)

  2. Or, drill a 1/2" or 3/8" hole down the length of your posts. Drill a larger hole (+1/8" or so) into the top of the stone wall. Use epoxy to mount a long threaded rod in the hole, then put a washer and bolt on top of the post and screw it down really hard. Counterbore the bolt, and put some kind of top-cap on to conceal it. (You could do the same thing with a length of pipe, and build "faux" posts around the pipe.)

  3. Finally, Simpson Strong-tie makes some weather-resistant post base fasteners where the bottom plate has just a hole in the center. These lift the bottom of the post away from the floor surface, to prevent water penetration. They don't look great, though, so you'll want to paint them or cover them with some kind of base moulding. (The one you linked to is about the biggest/ugliest of their bases.

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Rather than try to mount the 4x4s in the wall, I would suggest getting a wall anchor instead

enter image description here

These aren't cheap, but the advantages here are

  1. You can use an angle grinder to cut the metal fence off
  2. These install with a hammer drill bit (which is a LOT easier to find than a core drill)
  3. If the fence ever needs repair you just take the fence out of the base
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Have some 3-leg brackets bent out of 1.25" x 3/4" flat stock. One long leg goes down into a core-drilled hole through the concrete. The middle leg lays flat on top of the wall. The third leg, with bolt holes rises up 10". The post have dados on their bottoms and backsides to accommodate the brackets.

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