How do I maintain old wood windows?

The short answer

Old wood windows last when water stays out of the wood: moisture is the primary contributing factor in wooden window decay,^[1] so maintenance is mostly a yearly walk around the house, checking four things: paint, glazing putty, caulk and the sill. Fix what is failing before it lets water in. Repairs to wooden windows are usually labor intensive and relatively uncomplicated, which on small scale projects allows the do-it-yourselfer to save money.^[1]

Before you scrape anything

If your home was built before 1978, it may have lead-based paint; the older your home, the more likely it has lead-based paint.^[2] Any renovation, repair, or painting project in a pre-1978 home that has lead-based paint can easily create dangerous lead dust.^[2] EPA recommends homeowners hire a lead-safe certified contractor for such projects.^[2]

Generally speaking, the RRP Rule does not apply to homeowners doing projects in their own home, but it does apply if you rent all or part of your home.^[2] If a test shows no lead, or you decide to do the work yourself anyway, the EPA's practices include a spray mister to dampen surfaces before sanding or scraping, wet-dry sandpaper, and, for stripping, a low-temperature heat gun under 1,100 degrees Fahrenheit.^[2] If you rent, the rule applies to you, and a contractor you hire to disturb paint in a pre-1978 home must be lead-safe certified.^[2] Keep dust contained and keep children out of the room.

The yearly walk-around

Paint. Areas of paint blistering, cracking, flaking and peeling usually identify points of water penetration.^[1] Those are the spots to look at first, because the wood under them is the most likely to be wet.

Putty. The glazing putty should be checked for cracked, loose, or missing sections, especially at the joints.^[1] The putty on the inside of the pane matters too: the back putty on the interior side of the pane creates a seal which prevents condensation from running down into the joinery.^[1]

Caulk. If water is entering around the edges of the frame, the joints or seams should be caulked.^[1] A thin bead where trim meets siding, and where the sill meets the frame, is usually enough.

Sill. The sill should slope downward away from the building so water drains off.^[1] Clear leaves and dirt, and fix a spot where water stands.

Fixes you can do

Touch up paint before it fails, not after. Scrape back to sound paint, prime any bare wood and repaint, lapping the paint slightly onto the glass so it seals the edge of the pane. Removing excess layers of paint will facilitate operation of the window, so a sash that sticks may only need paint cleared from the stops and edges.^[1]

To reglaze a loose pane, take out the old putty by hand, lay a bed of glazing compound or putty around the opening, press the glass in, set it with points, and bevel a fresh bead of putty. Paint it once a skin has formed, usually in two or three days, lapping the paint onto the glass.^[1] Wear cut-resistant gloves and work on ground-floor windows only.

Weatherstripping is the comfort fix. Old felt weatherstripping is not likely to perform very satisfactorily,^[1] and appropriate contemporary weatherstripping should be considered an integral part of the repair process.^[1] Sash locks on the meeting rail keep the sash tightly closed so the weatherstripping works more effectively.^[1]

A storm window over the original is the next step. EPA estimates that, on a national average, ENERGY STAR certified (low-e) storm windows can save homeowners about 20 percent on their annual heating and cooling bills when installed over single-pane clear glass windows without existing storm windows.^[3] Windows with air leaks or drafts and degraded sills and sashes waste energy and can leak water into the walls,^[3] so fixing them is worth the effort.

A window that will not stay up usually has a broken cord. Replacing the sash cords with new rope cords or with chains is one of the most common work items.^[1] The steps are in how to fix a window that won't stay open.

Stop and call a pro if

• The wood is soft, spongy or crumbles at the sill, bottom rail or corners of the frame. That is rot, and it needs a carpenter.
• The house was built before 1978 and the job involves a lot of failing paint. EPA recommends hiring a lead-safe certified contractor.^[2]
• The window is above the ground floor. Reglazing and painting it means a ladder you should not be on.
• The frame is out of square or sagging, or the wall around it is stained. That points to framing or flashing trouble.
• The job is large. If the work is valued at $1,000 or more, a valid Virginia Contractor's License is required for the license category in which the contractor is to work.^[4] Ask for the quote in writing.

Getting help in Virginia

If you are weighing a bigger job, read how much window repair costs in Virginia. For a fogged double-pane unit, see why there is condensation between window panes. More guides are on the Home Repair answers page, and local pros are listed under Doors and Windows on Loclis.

When you are ready, describe the window and local pros will quote it in writing.