Architectural Metal Essentials: Correct Installation Methods for Decorative Metal Railings

The very first part of a building that we may touch as visitors is the handrailing, even before the door hardware. For the Architect or Builder or Stone Mason, upon return to a former project site, the shock of seeing a railing like this, literally tearing apart the masonry fabric they so carefully planned and laid, is almost too much to bear. The cost of the railings being small in contrast to the cost and labor behind the stone terrace and steps, yet the iron is not only barely useful for its intended purpose, but is now disrupting and damaging the materials around it. The metal fabricator too, is also not without anguish at a sight like this, yet what can be done to prevent it?

It seems simple enough, core drill a slab of solid stone or concrete, install post with anchoring grout, prop it up until the cement sets and move along. What could go wrong? Well, lots as it turns out, and water, the usual suspect in these kinds of matters, reappears for this episode too.

Now for the solution: Your first line of defense is to hire an excellent metal fabricator with a reputation for quality installation work. These firms have trained their installers to be wary of the pitfalls that create the kinds of issues we see here above. Paying more upfront, often yields much lower long term cost of ownership benefits! If for some reason that is not possible, then build the following requirements into the metals specifications here, and be mindful when setting posts into masonry whether you do it yourself or oversee the work done by others.

1.    Core Drill a hole that comfortably accommodates the size of the post and make sure that the edge of the hole is at least 3" from the edge of the masonry. Core Drilling uses friction and water to smoothly bore the hole, instead of Hammer Drilling, which literally pounds and grinds a hole in the steps. The larger the hole, the more impact and shock the hammer drill applies to cut the hole. Thus, because it doesn't have a vibratory component to the tool use, core drilling is much less likely to disturb the natural veins in the stone, keeping it intact and waterproof, especially on natural stone treads as shown here. Edge distance is also critical, too close, and the strength of the stone is compromised by the lever actions of the railings. 

2. During Install; Hard shim the post against the sides of the hole using metal shims in a way that won’t impede the flow of the anchoring grout. We like to use tapered steel shims we make ourselves. If this is done properly, the railing will feel firmly "set" even before grouting. This step will also help if the post is much smaller than the hole provided. By bonding the metal to the masonry step in this manner, the stresses of vibration and moment are transferred directly from metal to base stone which allows the anchoring grout to function mainly as a waterproofing agent.

3. Follow the grout manufacturer’s directions closely while mixing. Using the specified ratio of water and cement while closely observing the temperature of the stone and water. Pour the cement into the hole making sure it surrounds the shims and post fully. If the stone or water is too cold or too hot, or if the mixture is too thin or thick the grout will fail, and the stone and railing will follow. When used properly, pourable grout functions as both an anchor and as the waterproofing but when used with hard shims as above, its primary responsibility is only waterproofing which greatly extends the life of the grout.

4. Top up and mound the grout around the base of each post. This can be done 5-15 minutes after the first pour. This mounding effort is key to shedding water away from the post and waterproofing the hole. Pourable anchoring grouts all say they are "non-shrink" but the truth is that they all shrink a little or a lot as the water in the mixture evaporates as they set. When this happens in a post hole, the grout shrinks into the hole and it creates a cup which becomes a reservoir that holds water on top of the cement and against the bottom of the post. This is bad for the post and accelerates the demise of the grout. This is probably the most common mistake in all of the steps illustrated here above.

This image and the one below shows the common problem created by not mounding the grout. The grout shrinkage creates a retaining pond around the base of the post which compromises the longevity of the grout and the post. Standing water degrades the grout and accelerates rust as well as galvanic corrosion even is moderate climates with aluminum posts. Eventually, water penetration will fracture masonry steps with freeze thaw cycles.

This shows a properly grouted post. This must also be done under decorative post shoes as well. The decorative post shoe, which conceals the hole, can be lifted to inspect the quality of the grout which must be mounded to shed water.

Hopefully this will inform your next project and provide guidance for specification writers and metal fabricators alike. Railings anchored in this manner will outlast railings set in anchoring grout only and will protect the substantial investment in masonry over the same extended time by keeping water away from the holes and will protect the reputation of builder and metal fabricator alike in the long term.

For more information or to help you on your next railing project please contact the pros at Wiemann Metalcraft and for more Architectural Metal Essentials articles see the Wiemann Metalcraft Blog page.

Julius Blum, Wagner Companies, Sharpe Products, King Architectural Metals, Lawler Foundry all carry decorative cover shoes to conceal the post anchoring.

Por-Rok and Rockite are among a range of anchoring cements commonly used by railing installers.

Hilti North America offers a wide range of professional grades tools and adhesives designed specifically for masonry. Their Diamond Coring Tools are exceptional.

CS Unitec Offers a complete line of diamond Coring Tools

NOMMA is the National Ornamental and Miscellaneous Metal Association, the national trade association representing the railing industry.

AFA is the American Fence Association. Some fence contractors also fabricate and install railings.