Window Latch Fix: The Keeper Gap Check
The gap between latch and keeper, not the latch itself, decides whether your window actually seals or just looks closed.
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Most people blame a loose window latch on the latch, replace it, and the window still rattles. The real culprit is usually the keeper, the small catch on the upper sash, sitting a few millimeters too far from the latch hook. When that gap is off, the sashes never pull together against the weatherstripping, so cold air slips through even when the lock is flipped. Measuring that gap before you touch a screw tells you whether you need to shift the keeper, shim it, or simply tighten what is already there. Done right, it takes about 20 minutes, costs around $5, and you will feel the difference at the next cold snap.
What You'll Need
- Screwdriver, Phillips or flathead to match your screws, already in your toolbox
- Pencil, for marking the keeper position, free
- Wood filler or toothpicks with wood glue, to repair stripped screw holes, about $3
- Replacement screws, slightly longer than the originals, about $2
- Candle or paraffin wax, to ease the latch cam, free
- Clean rag, for wiping grime off the hardware, free
How to Build It
- Close the window fully and flip the latch as far as it will go. Note whether the hook reaches the keeper, barely touches it, or misses it.
- Measure the gap between the latch hook and the keeper with the window pulled snug. More than about 1/8 inch means the keeper needs to move.
- Mark the keeper's current position with a pencil outline, then unscrew it from the upper sash and set it aside.
- Repair any stripped holes by dipping toothpicks in wood glue, pushing them in, and snapping them off flush. Let dry 10 minutes.
- Reposition the keeper about 1/8 inch toward the latch, using your pencil mark as a reference, and drive in fresh screws until snug but not crushing.
- Clean the latch and keeper with a rag, then rub a little candle wax on the hook's contact surface so it slides without grinding.
- Test by locking and unlocking three times. The sashes should pull tight with light resistance. If it fights you, shift the keeper back a hair.
Hold a dollar bill between the sashes at the lock, close the window, and tug it. If it slides out freely, the seal is still loose. Run this test at every window to find which ones need a keeper adjustment before winter.
