Barriers against Break-Ins: Strengthening Vulnerable Doorways

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Doorway security begins with a metal door or a solid-core wood door. Hollow-core and paneled wood doors are both too weak to offer much protection. A metal door made of steel no thinner than 16 gauge is adequate. In wood doors, a core of laminated 2-by-4s is stronger than a particle board core.

Windows in an exterior door re duce security, as does a mail slot within reach of the latch. To see who is outside, install a viewer (below). Steel rods slipped into the edge of a wood door help thwart attempts to saw out locks and latches.

A Strong Frame: If your door jambs are made of steel—check them with a magnet—you need do nothing to strengthen them. With wood jambs, however, even the sturdiest door may be installed in ways that make a break-in easy.

To check the door mounting, be gin by removing a hinge screw. Re place short screws with 3-inch No. 10 wood screws that extend into the stud behind the jamb. For the best grip between screw and wood, use the hole-drilling method shown.

Unless adequately reinforced at hinges, deadbolts, and latches, many wood jambs can be levered away from the door far enough to free the bolt or latch. To determine whether your doorway has this weakness, remove the interior casing and inspect the spaces immediately outside the jambs. Add plywood filler and shims as necessary. Look into the deadbolt hole in the jamb. If you see wood at the bottom, replace the metal frame, or strike, with a heavy-duty strike box to encase the bolt in metal.

Special Cases: If your door opens outward, the hinges are outside of the house. it's a simple matter for a burglar to extract the hinge pins and remove the door from the frame. To foil any such attempt, use the technique that is shown below.

Sliding glass doors are especially vulnerable if the movable panel can be lifted out of the lower track. A few screws driven into the upper track solves the problem.


  • Electric drill
  • Bell-hanger drill bit (12’)
  • Drill guide
  • Chisel
  • Pry bar
  • Carpenter’s nippers
  • Mallet
  • Hammer
  • Hacksaw


  • Steel rods (1/4” diameter, 7 1/4” long)
  • Wood screws (3” No. 10)
  • Scrap plywood
  • Shims Common nails (2’ and 4”)
  • Finishing nails (1½” and 2”)
  • Sheet-metal screws (1½” No. 12)

SAFETY TIPS: Goggles protect your eyes from metal filings when you are hammering nails and drilling overhead.

Installing a wide-angle viewer. To see who is outside without having to open the door, install a viewer. Models with a 180-degree field of view, some times called fisheye viewers, make it impossible for a person to duck out of sight.

• At eye level in the center of the door, drill a hole as wide as the viewer shank, usually ½-inch.

• Insert the two halves of the viewer and screw them together by hand if the interior section is knurled, or with a coin if it's slotted.

Holes to Grip Screws Tight

1. The pilot hole.

Screw holes may be drilled with ordinary bits, as shown in these illustrations, or as a single step with a combination bit (photograph).

• To use ordinary bits, select a pilot-hole bit from the chart below.

• Wrap masking tape around the bit 1/16-inch farther from the tip than the length of the screw.

• Drill as deep as the tape permits.

2. The shank hole.

• Select a shank-hole bit from the chart.

• Tape the bit to avoid enlarging the pilot hole below the depth of the shank, then drill to the tape.

Matching Bits to Screws

Bits for pilot holes and shank holes.

This chart specifies the sizes of bits needed to drill pilot holes and shank holes for seven common gauges of wood screw. For sheet-metal screws, drill a pilot hole only. If screws supplied with the hardware are not identified by gauge number, determine their gauge by matching them against the actual-size drawings of screw-heads above. If screws supplied with the hardware are too short for secure fastening, use the bottom row of the chart to help you select longer screws of the same gauge.

Saw-proofing a Door

Steel bars for the lock area.

To shield the lock in a solid-core wood door, bore holes into the lock-side edge and insert steel rods.

• With a 12-inch-long, 1/4-inch bell- hanger bit and drilling no closer than 1 inch to the bolt or latch plates, bore five holes above the locks and five holes below them. Space the holes 2 inches apart, and use a drill guide to keep them at a 90-degree angle to the door edge. To make all holes an equal depth, wrap tape 8 1/2 inches from the tip of the bit.

• In cases where the door has a dead- bolt, drill as many holes as possible between the deadbolt and the main lock.

• Into each hole, tap a 7½” length of unthreaded 1/4-inch steel rod, then seal the holes with wood filler.

A Deadbolt Strike Box

1. Recessing the strike.

• Unscrew the old strike plate and enlarge the opening in the jamb with a chisel to accommodate the new strike box.

• Set the box in the jamb periodically as you work to check its position; the bolt of the lock must slide into the box without binding. If necessary, en large the opening for a good fit.

• Hold the box in the jamb and trace around the strike plate with a pencil.

• Chisel a recess, or mortise, within the outline so that the strike plate lies flush with the surface of the wood.

2. Fastening the strike.

With the strike in the jamb, use the screw holes in the strike plate and strike box as guides to bore into the studs beyond the jamb. Drill the holes to fit 3-inch No. 10 wood screws, using the hole dimensions and drilling method shown above.

Stiffening a Frame

1. Removing the side casing.

A securely braced doorjamb requires, at each of the points indicated in the inset, 4- by 6-inch fillers of 1/4-inch plywood and two pieces of door shim.

• Remove the strikes from the doorjamb.

• Working from the bottom up, remove both side casings with a pry bar, using a thin scrap of wood behind the bar to protect the wall (left). Extract nails left in the wall or casings with carpenter’s flippers, pulling casing nails through the back of the boards.

• Check the space between the jambs and the jack studs. If you find no shims at the locations indicated (inset), proceed to Step 2; if you do, go to Step 3.

2. Adding shims.

• Insert plywood filler behind the jamb, leaving space for the thick end of an untrimmed shim.

• Push the shim into the gap between filler and stud, then tap a shim with 3 inches trimmed from its thin end into the opening, thin end first, until the shims are snug. Score and snap off shim ends.

• Install one shim assembly behind each hinge; at the deadbolt strike, use two fillers separated by a gap for the box of a high-security strike.

• To secure the fillers, replace short hinge screws with 3-inch No. 10 wood screws and drive pairs of identical screws above and below each strike plate.

3. Reinstalling the casing.

• Nail the side casings to the jambs and the jack studs, from top to bottom, using 2-inch finishing nails in the studs and 1 1/2-inch finishing nails in the jambs, reusing old nail holes where feasible.

• Secure the side casings to the top casing with one 2-inch nail driven horizontally and another driven vertically into each mitered joint.

Securing Problem Doors

Pinning exterior hinges.

• Where a door swings out instead of in, remove pair of screws from each hinge—one from the jamb leaf and a second, opposite the first, from the door leaf.

• Hammer 4-inch nails into the empty screw holes in the jamb leaves, leaving 1/2 inch of each nail protruding.

• Cut off the nailheads with a hacksaw.

When hanging a new outward-opening door, use security hinges such as the one shown here. It has a metal projection that takes the place of the nail described above. A setscrew prevents the hinge pin from being pried out.

Keeping a sliding door in its tracks.

• Open the door and drill holes at 10-inch intervals in the over head track with an 11/64-inch bit.

• Drive a 1 1/2-inch No. 12 sheet- metal screw into each hole, allowing the screw-heads to protrude enough to prevent the door from being lifted out of its tracks but not so far that they will rub against the door as it's opened and closed (inset).

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