How do I keep wood windows from sticking?

Wood windows stick for three reasons: paint on the parts that slide, dirt and old hardware in the channels, and wood that has soaked up water and swollen. Keeping them working is mostly a matter of preventing those three, with a short check each year. None of it needs special skill.

Keep paint off the parts that slide

Paint is the most common cause of a sash that binds. Marvin's painting instructions are direct: "Do not apply paint to any surface which has sliding contact with another surface as this could impact the product’s ability to perform as designed."^[1] On a double-hung window, that means the channels, the faces of the stops and parting bead that the sash rubs against, and the edges of the sash itself.

Timing matters as much as where the brush goes. Marvin says to paint windows with the sash opened, or removed, and not close it until the paint is thoroughly dry.^[1] Closing a sash on paint that is still soft glues it to the stop. Keep finish away from the weatherstrip as well: Marvin warns that paints, stains and varnishes contain solvents that can damage the weatherstrip.^[1]

Old windows often have decades of paint on them. The National Park Service notes that removing excess layers of old, peeling and flaking paint will make a window easier to operate.^[2] To free the stop and parting bead, it describes running a utility knife along the seam between the interior stop, the parting bead and the jamb to break the paint bond.^[2] Score the seam, then work the sash gently. Never pry against the glass.

Keep the channels clean and the hardware tight

Grit in a track acts like sandpaper and a brake. Marvin's annual checklist includes cleaning sand, dirt and dust from window sills and tracks,^[1] and making sure all exposed hardware screws are tight.^[1] A sash lock or lift that has worked loose can hold a sash crooked, so it rubs on one side.

For crank-operated casement and awning windows, Marvin recommends a dry lubricant on the gears of crank windows.^[1] On a sliding wood sash, a dry lubricant rubbed lightly on the channels usually helps once the channel is clean. Oil and grease are a poor choice there: they collect dust and can stain bare wood.

Keep water out of the wood

Swelling is a moisture problem. Marvin says windows and their frames are susceptible to deterioration if left damp,^[1] and the Park Service says moisture is the primary contributing factor in wooden window decay.^[2] It also notes that years of opening and closing, along with seasonal temperature changes, weaken the joints and cause slight separation,^[2] which lets more water into the end grain.

The paint is your early warning. According to the Park Service, blistering, cracking, flaking and peeling paint usually mark where water is getting into the wood.^[2] It also suggests you check the sill slopes down and away from the house so water drains off,^[2] and notes that caulking the joints between the sill and the jamb helps reduce further water penetration.^[2]

Make it a yearly job. Marvin recommends you check the exterior of wood windows at least once a year for failing caulk or paint that has cracked, peeled or bubbled.^[1] Where cuts or other damage have exposed untreated wood, Marvin's instructions call for a water-repellent wood preservative containing at least 0.5% IPBC^[1] before paint. Check the glazing putty at the same time: the Virginia Energy Savers Handbook says small cracks in glazing putty may only need a good coat of paint, while larger cracks or missing putty mean the sash needs reglazing.^[3]

When sticking is a sign of something else

A window that sticks only in August is swelling. A window that has started sticking all year, or slams down, may have a different problem:

• Rot. Press a sharp awl into the sill and the bottom of the sash. The Park Service's test: decayed wood lifts up in short, irregular pieces when pried with an ice pick, while sound wood separates in long fibrous splinters.^[2]
• Broken sash cords or balances. A sash that will not stay up, or drops hard, has lost its counterweight. The Park Service says replacing broken sash cords is one of the most common window repairs.^[2]
• A moving frame. If several windows and doors start binding at once, the house may be settling, and that needs a look from a contractor.

Older homes and lead paint

Windows are where old paint wears first. The EPA says to check all painted areas that rub together or get lots of wear, like windows, doors and stairways, for any signs of damage.^[4] It also advises that you wipe window sills with a damp sponge, cloth or paper towel, and not use steel wool, scouring pads or abrasive cleaners.^[4] The EPA's renovation rule says the RRP Rule generally does not apply to homeowners working on their own home,^[5] but the agency recommends homeowners hire lead-safe certified contractors for all RRP projects in pre-1978 homes,^[5] and scraping or sanding window paint is that kind of project.

Stop and call a pro if

• The sill or the bottom rail of the sash is soft or crumbles when probed.
• A sash will not stay up, slams down, or a cord or balance is broken.
• The window is on an upper floor and the outside work needs a tall ladder.
• The house was built before 1978 and freeing or repainting the sash means scraping or sanding old paint.
• Several windows and doors started sticking at the same time, or new cracks have opened around them.

If the window is drafty as well as stiff, see why there is a draft around windows, and for help choosing who to hire, whether to hire a handyman or a carpenter for doors and windows. You can browse handyman services, handymen around Blacksburg and other handyman answers. For a window that will not budge, describe the window repair once and local businesses quote it.