Window stops are small parts, but the job has a fire-exit side that most guides skip. Before you put a stop on any window, decide whether that window is a route the household would use to get out of the room. If it is, the stop must release from inside without a key, a tool, or a second person, and it must not reduce the opening below what the fire department or building inspector allows for an exit window.

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Step 1: Pick the windows and check the exit rule

Walk the house and list each window your parent uses at night or would use in an emergency. Ask the local fire department or building inspector whether a stop is allowed on that window. St. Louis City and St. Louis County run separate inspection offices, so ask the one that covers your address. Write down the answer and the name of the person you spoke to.

Step 2: Measure the sash and the frame

Open the window to the point where you want it to stop and measure the gap the sash would travel. Measure the frame depth, because a stop screws into the frame and not into trim or the sash. Check the window type. A double-hung window, a casement, and a sliding window each take a different stop, and buying the wrong type means returning it.

Step 3: Choose the release before you buy

Look for a stop that releases with a simple push or a lever you can work from inside. Avoid any stop that needs a key or a pin you cannot reach while standing. Ask the seller or read the product page to see how the release works, and check whether the instructions show the release from the inside.

Step 4: Install in order

Mark the screw holes, pre-drill, and fasten the stop to the frame. Use the screw length the package calls for, and do not force a screw through the frame into an empty cavity. Work from the lowest window to the highest so any ladder work is done in one trip.

Step 5: Test it from inside

Open the window until the stop catches, then push against it hard, the way a person in a hurry would. Confirm the stop holds, then release it from inside with one hand. Do this at every window you fitted. If any stop fails the release test, take it off before anyone uses that window.

Step 6: Record what you did

Write down each window, the stop model, the release method, and the day of the test. Keep that note with the house papers. If someone else opens or closes a window later, they can check the same release without guessing.

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The Window Stop Is a Fire Exit Question: Install It Start to Finish Without Blocking the Way Out