Ease off the trigger if you're using a nail gun or screw gun on your home-remodeling project. A poorly placed nail or screw can damage pipes and wiring.

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It happens all too often: A nail or screw hits a plumbing or electrical component in a wall. With the advent of pneumatic siding, framing nailers and self-feeding drywall screw guns, the number of incidents has increased. A fully automatic weapon shooting razor-sharp projectiles up to 3.25 inches long, these guns make it too easy to punch 30 nails into an 8-foot-high wall in 10 seconds or less, with half of them routinely missing the intended target.

It feels and sounds different when a nail hits a pipe, a stud or just air inside a wall, but it takes an experienced hand to tell the difference. It also takes someone secure enough and ethical enough to ‘fess up and tell a responsible party that he or she just hit a mechanical component.

While a missed fastener (called a “shiner”) may cause damage, the real sitting ducks are pipes and unprotected wiring drilled and passing horizontally through the inside of a wall stud. A 2×4 is only 3.5 inches wide at best. Most codes require a minimum of 1.25 inches from the edge of the hole to the edge of the stud on both sides before protection in the form of a steel nail plate is required. This is true of Romex, even armored cable, metal clad and UF wiring. And of course all plastic piping can be easily pierced.

Cast-iron piping is immune to all but tank-busting rounds, which thankfully have not yet been developed for nail guns. Copper pipes can actually absorb a nail or screw, then self-seal and begin leaking after rust sets in. This may be a matter of weeks, or it might take years before being finally detected. Copper routinely gets nicked, which also can cause eventual leakage.

In my opinion, that 1.25 inches isn’t enough. That leaves only a one-inch hole, perfectly centered, in a 2×4 wall without required protection. During cabinet installation longer screws are used, and they routinely penetrate more than 1.25 inches into the stud. All trades use longer screws than necessary, and all have inexperienced help, particularly with the inexperienced help doing the grunt work of “nailing off.”

In a two-level apartment I am remodeling each lower-level common bathroom wall is littered with plumbing pipes going in every direction. With sloppy drywall installation, lack of nail plates, and tenants using nails and screws to hang pictures and doilies over the years the ABS (plastic) drain plumbing looked like Swiss cheese. Each apartment had enough holes and subsequent wet spots, sewage smells and rot that it required removing all the drywall to find and repair every pipe completely. The new tenant policy is now not just no smoking, but NO NAILS OR SCREWS IN THE BATHROOM WALLS!

Darrell Hay is a local home inspector and manages rental properties. Send e-mail to dhay@seattletimes.com. Sorry, no personal replies.