Concrete Anchors

DEAR MIKE: I want to install a waist-high railing between the exterior wall of my home and a column on my front porch. The railing has holes at the bottom so that it can be mounted into the concrete, but therein lies my problem. How can I do that? -- Joe C.

DEAR JOE: Securing the railing into the concrete is surprisingly simple: choose an anchoring method, drill a hole and secure the railing.

Mounting something into concrete uses the same principle as that of a toy that I remember. I think it was called Chinese handcuffs, and it was a little tube just large enough so you could stick your index fingers into each end. It was made of a woven bamboo-type material and after you stuck your fingers in and then pulled to get them out, the weave in the handcuffs would stretch and not let go of your fingers. The beauty of this gadget was that as you struggled to remove your fingers, you were defenseless to protect your lunch money. Oh, the horrors of the playground.

Anyway, the hole you drill into the concrete will house a fastener that will expand to hold down the rail. The more you tighten the fastener, the more pressure is exerted against the concrete walls and the tighter the object is held to the concrete.

There are different types of anchors available, each costing around $1. For this project, I would use a "redhead" drop-in anchor.

Place the rail where you want it and mark the locations for the holes. First, drill a hole into the concrete (according to the manufacturer's instructions) with a masonry bit. The quickest way is to use a percussion masonry bit chucked inside of a hammer drill. The hammer drill not only spins the bit to bore the hole, but it simultaneously uses a hammering action while the bit is spinning.

Since it doesn't seem like you have a lot of holes to drill, save yourself the expense and just use a regular drill. It'll take longer, but the results will be the same.

Once the holes are drilled, drop in the anchor (You may have to tap it with a hammer.). Now the threads of the anchor are sticking out of the hole. Remove the washer and the nut and set the railing over the threads. Next, replace the washer and the nut on the threads and screw it down. This will draw the anchor toward the hole's opening.

There will be a wedge with a sleeve at the bottom of the anchor, and as the wedge draws into the sleeve, the sleeve wedges against the inside of the hole locking it into place.

You could also use a lead shield, which is pretty much the same story as the drop-in anchor except that you attach the railing by screwing a bolt into the lead shield from the top.

There are also "tapcon" anchors, which look like regular screws with double threads. These anchors are smaller by comparison, and consequently so are the holes you'll drill. Depending upon how deep you imbed them into the concrete, these anchors can withstand pullout in excess of 1,800 pounds with a shear strength of more than 1,600 pounds. Now that's slick.

Need Help? Contact Us!