Q. I need to secure the base of a wrought-iron handrail to an exterior granite landing. My plan is to drill holes into the stone and use anchors. What's the best way to do this without cracking the stone, and what should I use for anchors? I am concerned that wedge anchors might cause cracks.
A. Bruce Zaretsky, a landscape designer and contractor who lives near Rochester, N.Y., responds: I agree that you should think twice about using wedge-type or masonry anchors in this kind of stone. When you drill and anchor so close to an edge (as you will when installing a railing), there is a good possibility that you'll crack the stone or break off a section.
Instead of anchors, we've had good results using hydraulic cement, which is a fast-setting cement product used most often for filling holes in watertight vessels.
We drill holes that are as deep as possible and one size larger than the 9/16-inch- or 1/2-inch-diameter bolts we typically use, fill the holes with the cement, and then place the rail and spin the longest bolts possible into the holes. You'll need to do this quickly, since the cement will be rock hard in about 10 minutes.
To drill the holes, we normally use a hammer drill and a bit specified for the material we're drilling (in most cases, a diamond-tip bit). If we're worried about cracking the stone, we use a core drill with a diamond bit, because it doesn't shake the way a hammer drill does.