Spring Bronze Weatherstripping: Spring Copper and Door Copper Flashing Explained

Spring bronze is the traditional weatherstripping for old wood doors and windows. It is a thin, springy strip of bronze nailed to the jamb. When the door or sash closes, the strip flexes and seals the gap. When it opens, the strip springs back. Installed right and never painted, it can last for generations, and it lets you keep the original door, sash, frame and trim.

Is spring bronze the same as spring copper or door copper flashing?

If you are searching for spring copper, copper weather stripping for doors or door copper flashing, you may be looking for traditional spring bronze weatherstripping. It is the thin, flexible metal strip nailed around the sides and top of a door jamb. It presses against the closed door to block drafts and springs back when the door opens.

This is not the same as copper flashing or a sill pan installed beneath a door threshold to manage water. If the metal goes around the jamb and touches the door edge, start with spring bronze. If it belongs under the sill, you need threshold flashing or a sill-pan detail.

• Sides and top of the door jamb: spring bronze weatherstripping
• One typical door: One-Door Spring Bronze Kit
• Several doors or windows: 100 ft spring bronze roll
• Beneath the threshold: waterproof threshold flashing or sill pan—not this product

Shop the One-Door Kit  |  Shop 100 ft Rolls  |  All Spring Bronze

Quick answers

• How much do I need for one door? About 17 feet covers both sides and the head of a typical door. That is what our one-door kit includes.
• What width? Pick a width a little narrower than the thickness of the door or sash. For a typical 1-3/4" exterior door, 1-3/8" is usually right.
• What nails? Small solid brass nails. They drive straight through the bronze, so no pre-punched holes are needed.
• Can I paint it? No. Paint kills the spring and the seal. Keep painters away from it.

Step 1: Make sure the door is aligned first

Weatherstripping can't fix a door that sags, rubs or won't latch. Check the hinges, the latch and the gap around the door before you start. Do the 1-minute door alignment check.

Step 2: Measure the gap

Slide playing cards into the gap between the door and the jamb until they are snug, then measure the stack. Check several spots, because gaps vary around an old opening.

• Under 1/16": plane the door or sash first so it doesn't bind.
• 1/16" to 3/16": standard (single-leaf) spring bronze is the right choice.
• 3/16" to 1/4": V-shaped spring bronze is stiffer and seals a bigger gap. Ask us and we can source it.
• Over 1/4": build up the door or reduce the opening first.

Step 3: Choose the width

Choose a width slightly narrower than the thickness of the door or sash. We carry 3/4", 1", 1-1/8", 1-1/4" and 1-3/8".

Door or sash thickness	Typical spring bronze width
1-3/4" exterior door	1-3/8"
1-3/8" door	1-1/8" or 1-1/4"
Window sash	Narrower than the sash thickness; measure yours

Step 4: Install it

1. Practice on a 1 ft piece first. It's the best way to get a feel for how the bronze bends, nails and seals.
2. Cut the strips for each side and the head with tin snips.
3. Set the direction. Nail one edge to the jamb. The free (unnailed) edge sits close to the door stop without touching it. On an inswing door, the free edge faces the exterior.
4. Nail it. Use solid brass nails, spaced about 1" apart. Start the hole with an awl, or predrill the bronze with a 1/16" bit, then drive the nail.
5. Work around hardware. At hinges and the strike plate you can stop the bronze and use felt there, carefully notch the bronze around the hardware (watch the sharp edges), or run it over the hinge leaf (then the hinge can't come off without removing the strip).
6. Close the door and test. It should close and latch without force and you shouldn't see daylight.

Windows

On double-hung windows, set the free edge close to the parting bead. If the upper sash operates, notch around the pulley so the free edge stays continuous. At the head, sill or meeting rail, spring bronze can fight the sash lock; sometimes doing the jambs only is the smarter choice.

Troubleshooting

The door is hard to close after installing spring bronze

Check that the free edge points the right way (toward the stop, not the room), that the strip isn't too wide for the gap, and that the door is aligned. A door that was already tight will feel much tighter with weatherstripping.

It squeaks or rattles

Check for loose nails or a strip that isn't sitting flat against the jamb. Re-set any nails that have backed out.

The color doesn't match my old strips

Spring bronze varies from coppery to brassy from batch to batch. It's unlacquered and tarnishes to brown over time. Performance is the same.

Spring bronze or interlocking?

Spring bronze presses against the door. Interlocking weatherstripping uses two metal profiles that hook together when the door closes. Spring bronze is easier to retrofit and handles seasonal swelling better. Interlocking is the premium seal but needs more carpentry. If your door already has interlocking strips, replace them with interlocking. Compare the two.

Want it done for you?

Classic Door installs weatherstripping on historic doors and windows across New England. Send photos of the full opening, the door edges and the jamb and we'll tell you what you have.

Spring bronze FAQs

How long does spring bronze weatherstripping last?

Installed correctly and never painted, metal weatherstripping can last many decades. We regularly find original strips still working in old houses.

Can I buy less than a 100 ft roll?

Yes. The one-door kit has about 17 ft and the brass nails. Use a 100 ft roll for several doors or a whole house.

Does spring bronze work on outswing doors?

Yes. Set the free edge so it sits close to the stop on the side the door closes against.

Should I replace my old spring bronze?

If it's flattened, kinked, painted or missing pieces, yes. Here's how to tell.