This month’s article is a bit longer than usual, because the work involved was substantial. I doubt if any of you will face the same situation as this, but hey, maybe you’ll learn something anyway, or at least appreciate a bit of “out of the box” thinking!
My son has a back yard which slopes gently in a west-east direction, but at the southern edge, it drops off dramatically! He wanted to install an ornamental fence to help keep his young son from losing balls over the edge, and frankly, to dress up the yard in a way that matches the fancy historic house he lives in. Long story short, he and I traveled to NY State where we located someone who had multiple sections of old wrought iron fencing. We brought back 12 panels and enough posts to install them. Here are pictures showing a few of them:
In the picture of the posts, I’ve already ground off the former welds. The new attachment points of panel-to-post would likely be at different spots on the posts than they once were. There are also a lot of little issues needing attention, like the broken-off tips on several panels. (We have ones to install in those places.)
There really were two major problems. The first is that the posts were cut off at the ground at their previous location, so there’s not enough post length to securely anchor into a hole/concrete. By making the tops of the posts in the new location “lower” than they were relative to the top of the panel would give a few inches at best to be below ground level. The second issue is that each panel was welded on-site to match the original topography. I didn’t want to break the welds on each baluster and re-weld everything, so each panel would need to be selected individually for the spot it would occupy, trying to match its “slope” to that of the new ground.
I had a wild and crazy thought that I could make a column of concrete/rebar with outside dimensions to match the inside dimension of each post, and slip the post over it. That, I reasoned, would give a bit of stability to the post. (Time will tell if that thinking was good!)
I’ve often extolled the virtues of rapid-setting structural mortar, and this is what I wanted to use. It begins to set in 15 minutes, and reaches an incredible strength of over 6,000 psi with proper curing. Other brands are likely available, and I’m not a paid spokesperson for this brand, but it’s what I use:
I built a wooden “trough” of the proper dimensions so that the column of concrete (technically, mortar) would just fit into the post. I made it long enough to reach from the below-ground frost depth to the approximate top of a post. (The posts vary in height, so I’d be cutting them on-site to exact length.) I cut sections of #4 rebar (1/2” diameter, as rebar is named by the number of “eighths” in its diameter) to fit into the trough. Here’s a picture of a length of rebar, the trough, and a completed column:
Let’s step back and see the whole scenario. The trough had to be substantial, but easily taken apart if needed to remove the concrete column. A “release agent” needs to be applied so that the concrete doesn’t adhere to the wood. Lots of folks use oil of some sort, but I’ve found that a good spraying with WD-40 works well, is super easy, and is a lot less messy than using oil.
Because the mix sets rapidly, I needed to work QUICKLY! I hand-mixed the mortar in a small plastic oil-changing pan, troweled it into the trough to about halfway, and then pressed the rebar into it before fully filling the trough. Packing the mix hard into the trough would yield a column without too many voids.
Concrete (and this mortar) sets, as opposed to hardens. That means that keeping it moist is important for reaching structural strength, so I sprinkled the column every once in a while for several hours. After a few hours I popped the column right out of the trough!
Obviously, every post had to have a hole dug. Other than an occasional rock, it wasn’t too difficult. I had the power to the garage turned off since the installation was relatively close to where a buried electrical line exists. (By the way, calling the normal “locating service” was done, but the only electrical line they would locate was the main service, not a private line to a garage.)
The concrete column was set into the hole and the fencepost slipped over it. There was a lot of “fiddling around” with the post height, by placing the fence panel next to it until the best fit could be figured out. A taut string stretched from end-to-end guided the layout for alignment.
Before any welding, it’s important to clean up the metal. Wrought iron is relatively rust-resistant, but good welds require removal of any paint and surface oxidation.
I used a pipe clamp to hold things together at the proper position for welding (and later, while pouring concrete into the hole).
I used a wire-feed electric welder, with flux-core 0.30” wire. This type of welder has a lot of “splatter” which needs to be scraped off for appearance sake, but that doesn’t affect the strength of the weld. A decent weld looks like a series of very small circular dabs of metal.