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Q.What’s the best way to cut through a concrete wall? A concrete saw won’t cut all the way through an 8-inch foundation wall. We’ve even tried suspending a jackhammer from the floor joists, but this is awkward at best and leaves a ragged edge.

A.George Smith responds: You’re not the only one who’s struggled with this problem. You can beat yourself up trying to cut a door or window through a foundation wall.

The easiest way is to rent one of two specialty saws, if available. A Partner ring saw can cut to a depth of about 10 inches (Partner Industrial Products, 905 W. Irving Park Rd., Itasca, IL 60143; 708/773-2801). Or RGC makes a concrete chain saw that cuts to a full 15 inches (RGC Construction Equip., P.O. Box 681, Buffalo, NY 14240; 716/895-1156). Both run on a hydraulic power pack and require special (read "expensive") diamond blades.

We don’t have access to these saws here on Tortola, where everything is built with concrete. So we make do with a standard 14-inch concrete saw (we use the Bosch).

To support the saw, make this simple rig: Build an A-frame out of 2x4s, either screwing the top of the frame to the joists, or attaching a third leg to make a freestanding tripod. Throw a rope over the cross rail of the A-frame, tying one end to the front (top) handle of the concrete saw and the other end to a 5-gallon mud bucket. Then fill the bucket with enough sand or rubble to counterweight the saw.

The counterweight will not only make it easier to keep the saw elevated, but it will allow you to apply light, even pressure as you cut. When cutting concrete, you don’t want to bear down on the saw. If you hit rebar, you’ll see the sparks. Back out, then go back into the cut very gently.

A 14-inch saw has a depth-of-cut of about 4 7/8 inches, so you’ll have to cut from both sides of the wall. Before you begin, drill holes at each corner, keeping the hammer drill as straight as you can. Then you can draw layout lines on the wall to align your cuts on both sides. If the wall will be plastered, overcut the corners. If not, cut to the corner holes, then bust the remaining pieces out with a sledgehammer and cold chisel.

Most of the time we use a silicon-carbide abrasive blade for concrete and masonry. Diamond blades are nice, but very expensive ($400 to $800 each).

George Smith owns Island Equipment on Tortola, British Virgin Islands.