Your window's stuck. Find out why before you reach for a hammer

Quick answer: Look before you pry. Most stuck windows are painted shut, swollen, gummed up or hung on broken hardware, and each one needs a different fix. Score the paint, pry gently at several points, clean and lubricate the track, and only plane wood as a last resort. Budget $25 to $40 if you own nothing.

Do this before you touch the window

Check the lock. Seriously. Half the "stuck" windows in America have a latch that's a quarter turn from open.

Then think about where you're standing. If this is a second-story window, don't lean out and shove. Pry from inside where you can, keep your feet on the floor, and stay off the ladder if you can't do the job with two hands planted. Push on the frame of the sash, never the glass. Glass flexes, then it breaks, and then you're dealing with a bigger problem and a bleeding hand.

Wear gloves and safety glasses. Paint chips and old glazing fly.

If the house was built before 1978, assume the paint could contain lead until a test says otherwise. Hardware stores sell swab kits, roughly $10 to $30. Until you know, don't dry-scrape or dry-sand it, and mist surfaces lightly with water before you cut or scrape. Sweep up the chips with a damp rag, not a broom. Rules for contractors on lead-safe work are federal, and local requirements differ, so check yours.

Diagnose it: four causes, in order of likelihood

1. Painted shut. Look at the seam where the sash meets the stop (the wooden strip along the side) and where it meets the sill. A bead of dried paint bridging that gap is your answer. This is the most common cause on any window that's been repainted without being opened first.

2. Swollen wood. If it sticks worse in summer, or in one corner, humidity is swelling the sash. Run a fingernail down the edge. Bare, rough wood with no paint means moisture got in.

3. Dirty or dry track. Sliders and vinyl windows especially. Grit, dead bugs and old dirt pile up in the channel and the sash drags on it. You'll see it.

4. Failed hardware. A double-hung that won't stay up, or drops when you let go, has a dead balance or a broken sash cord. A slider that grinds or tilts has worn or misadjusted rollers. A crank window that spins freely has a stripped operator.

Spend two minutes on this. You'll save an hour of wrong work.

Fix one: paint

You need a utility knife with a fresh blade ($10 for a decent one) and a flexible putty knife, 5-inch ($8 to $12). A paint zipper tool does the same job as the knife and costs about $6.

Cut the paint seam along the full length of the sash on the inside, both sides and the top. Don't saw. Pull the blade through in one steady pass, then do it again. Run the putty knife into the cut and slide it up and down to break what's left.

Go outside and do the same on the exterior seam if you can reach it safely. A paint line on the outside holds just as hard as the one on the inside, and people always forget it.

Now try the window. Many of them let go at this point.

If it still won't move, work your way into leverage.

Leverage, done without wrecking the sash

Get a flat pry bar, about $10 to $15. A thin, wide one spreads force over more wood. A screwdriver concentrates it into a dent.

Slide a scrap of wood or a folded rag under the bar's pivot point so you don't crush the sill. Pry up at the bottom rail, a few inches at a time, moving along the length. Don't wrench one corner high while the other stays locked. That racks the sash, cracks glazing putty and sometimes snaps a joint.

If it moves a little and sticks, stop. Tap the side of the sash rail with a rubber mallet, or a hammer on a wood block, near the sticking point. Never directly on the glass. Short taps. If you're swinging hard, you've got the wrong cause.

Patience wins here. Prying, tapping and trying again for fifteen minutes beats forcing it for one.

Fix two: tracks, tracks, tracks

A vacuum with a crevice tool, a stiff brush and an old toothbrush get most of the grit out. Wipe the channel with a damp rag and a little dish soap, then dry it.

Then lubricate. Use silicone spray, about $7 to $10 a can, or a dry PTFE lube. Oily sprays like WD-40 attract dust and turn the track into paste within a season. On bare wood, rub paraffin or the end of a plain candle along the runners instead. It's cheap and it works. Don't put anything oily on wood you plan to repaint.

This is the same logic as the garage door: a dirty, dry track is a stuck track, and the fix is about cleaning the path before you blame the opener.

On sliders, look at the bottom edge of the sash for small adjustment screws. Turning them raises or lowers the rollers. A quarter turn at a time, both sides, checking after each. If a roller is cracked or flattened, replacement sets run roughly $10 to $25 and are model-specific, so take the old one to the store.

Fix three: swollen wood, the last resort

If the sash is simply too big for the opening, you have two choices. Wait for the dry season, or take a little wood off.

Mark the tight spot with a pencil. Take the sash out if you can, or work in place with a sanding block and medium-grit paper (a few dollars). Take off a tiny amount. Then seal the bare wood with primer and paint, including edges nobody sees. Raw wood swells again by August. That's the mistake that brings people back to this job every year.

A hand plane works faster, and it's also faster at ruining a window. If you've never used one on a sash, practice on scrap.

When to stop and call someone

Call a licensed window or carpentry pro if:

• The frame is out of square or the wall has settled, so the opening has changed shape.
• The wood is soft or rotted. A screwdriver should not sink in.
• The glass is cracked, or the sash is heavy enough that you can't hold it safely.
• Spring balances are involved. Some are under tension and can snap back hard.
• The house is old, the paint tests positive for lead, and the job goes beyond a light cut.

Also know this: bedroom windows are often required to open as an emergency exit, and codes vary by city and state. If you replace, modify or fix one, don't leave it screwed or painted shut. Ask your local building department what applies before you permanently change anything.

Heavy or tall double-hungs with failed balances are doable, and parts are often $15 to $40 a pair, but they're not a first project. A pro can do it in an hour and give you a warranty.

Finish it like you meant it

Wipe the track clean before you walk away. Sweep up every paint chip. Put a fresh blade in the knife and wipe the tools down before they go back in the drawer, because somebody will borrow them, and the next man will thank you.

Then open the window. Let the room breathe. You earned it.