A cold window might need a tube of caulk. It might need several thousand dollars’ worth of replacement work. Worn weatherstripping and a rotting frame feel about the same from the couch once the heat comes on.
Before thinking about the window’s age, figure out what has failed. Fog between the panes, moving air around the sash, soft wood at the sill, and cold glass point to different problems, and several of them can be repaired without replacing the entire window.
What Is Making the Window Cold?
Run a hand slowly around the sash, then look through the glass rather than at its surface. Those two checks sort out a surprising number of cold-window complaints.
Air moving across your skin usually points toward a leak around a moving or stationary joint. Fog trapped where you cannot wipe it away points toward the sealed glass unit instead. If the fog is faint, shine a flashlight across the glass at a low angle. Haze inside the unit becomes much easier to see.
Fog Trapped Between the Panes
Cloudy glass that will not wipe clean from either side is a fairly clear clue. Fog or a milky film between two panes usually means a failed window seal, and another bead of exterior caulk will not fix what happened inside the glass unit. Double-pane windows have a sealed space between the layers of glass. Once that edge seal fails, insulating gas can escape and moisture can work its way into the space.
That does not always make the window an emergency. One cloudy pane may still keep wind and rain outside for years. What has changed is the performance of the sealed glass unit, not necessarily the condition of the frame around it.
Moving Air Around the Sash
A draft that brushes across your hand is different. Worn weatherstripping where the sash closes against the frame is one common culprit. Cracked caulk between the stationary frame and the surrounding wall is another. The two fixes are not interchangeable: caulk goes on cracks and joints that never move, and weatherstripping goes where the sash opens and closes.
A stick of incense works as a leak detector on a windy day. Move it slowly around the window edges. The smoke bends or flutters where air is getting through, and unlike a candle, it is easy to watch and does not drip wax onto the sill.
If the frame itself is sound, fixing those leaks may be all the window needs before winter. Exterior caulk still needs suitable weather to cure, so that job gets harder once temperatures stay near or below freezing.
What Can Be Repaired When the Frame Is Still Solid?
A failed sealed glass unit does not automatically require a whole new window. When the sash and frame are still dry, square, and solid, a glass shop can measure the existing opening, order a replacement insulated glass unit, and return to install it. Angi’s September 2026 cost data puts professional replacement of a standard double-pane glass unit at around $181 to $414. A full new window can run anywhere from roughly $300 to $3,000, depending on size and type.
A drafty window with clear glass may have even cheaper options. Fresh weatherstripping or caulk might solve the leak. An interior storm panel or insulated covering can also buy another winter when a larger replacement project is already planned for a later year.
When Damage Means the Whole Window Has to Go
Take a screwdriver and press the tip gently into the sill, especially at the corners and along the bottom of a wood sash. Solid wood should resist it. Wood that gives way, flakes apart, or feels spongy has a moisture problem that glass replacement will not solve.
A small isolated soft spot may be repairable with epoxy and careful sealing. Rot that runs through the sill, frame, or structural joints changes the decision. Putting a new glass unit into a deteriorating frame leaves the expensive part of the problem untouched.
Water staining around the opening deserves the same attention. Before ordering a replacement window, find out whether water is getting through the window itself, failed flashing, siding, or another joint nearby. Otherwise, a brand-new unit can end up sitting in the same wet opening.
How Old Is Too Old for a Window?
There is no single replacement age, but InterNACHI’s life expectancy chart for home components puts most residential windows between about 15 and 40 years. Aluminum sits at the low end, vinyl and fiberglass run 20 to 40 years, and well-maintained wood can go past 30. The same chart gives double-pane glass units 8 to 20 years, which is why fogged glass often turns up long before the frame wears out. Installation quality, maintenance, and weather exposure explain much of the spread.
So a 20-year-old window is not automatically finished. If the frame is dry and square, the hardware works, and a replacement glass unit is still available, repairing it may make more sense than replacing everything. Parts availability is the catch. Manufacturers eventually stop producing compatible sashes or glass units for older lines. A problem that once called for a glass order can then turn into a sash replacement or a whole new window.
Several units beginning to fog, stick, or leak during the same couple of seasons also changes the math. One failed window looks like a repair. Repeated failures across an original set suggest the rest may not be far behind.
Why a New Window Can Still Feel Drafty
Replacement itself does not guarantee the draft disappears. Many replacement windows are installed as inserts, sometimes called pocket windows, inside the existing frame. An insert leaves the original frame in place instead of stripping the opening down to the framing. Air entering at the old frame-to-wall joint will still be there afterward unless that joint is sealed during the work.
Ask what the installation includes, line by line, before accepting a quote. If it is an insert project, the proposal should spell out how the old opening will be air-sealed and how exterior water management will be handled. A low price for the window itself is less impressive if cold air still finds the same path around it afterward.
If You Need to Finance a Full Set
Financing comes into it once two damaged windows turn into ten or twelve. The Federal Reserve raised its target range a quarter point on September 16, 2026, to 3.75% to 4%. The Fed’s move does not set the rate on a window loan directly, but HELOCs feel it quickly. Most have variable rates tied to an index such as the prime rate, so the payment can change long after the windows are in.
For someone with two fogged windows and eight healthy ones, the repair quote comes first, before anyone finances a full set. Replacing the failed glass now may restore those two windows while leaving the larger project for another budget year. If borrowing still makes sense, ask the lender what index the rate follows, how often it can adjust, and what the payment would be if the rate rose another half percentage point. Those three answers say more about the loan than the first month’s payment does.
One former incentive is also out of the calculation for 2026. The Energy Efficient Home Improvement Credit previously covered 30% of qualifying window costs, subject to a $600 annual window limit, but the IRS says the credit is not available for qualifying property placed in service after December 31, 2025.
Can Windows Be Replaced Once It’s Cold Out?
Yes. Window replacement does not automatically stop when winter starts. Experienced crews commonly remove and replace one unit at a time rather than opening every room at once. Working one window at a time keeps the house from sitting open to the weather for long stretches.
Cold weather slows or prevents proper curing for some caulks and sealants. A crew working below freezing may use a product rated for lower temperatures or leave certain exterior finishing work for a milder day. Before signing the contract, ask what sealant will be used at the temperatures forecast for install day and what the plan is if the weather turns.
A Few Questions That Come Up Before Winter
How long does it take to replace just the glass in a window?
The physical swap may take only an hour or two, but the replacement glass usually has to be made first. A glass shop measures the existing sash, orders the sealed unit to those dimensions, and schedules installation after it arrives. That manufacturing wait can stretch the project into several weeks. Calling when fog first appears in October gives the shop more room to finish the job before the coldest part of winter.
Does homeowners insurance pay for a fogged or drafty window?
Usually not when the cause is ordinary wear and tear, such as a failed seal or worn weatherstripping. Insurance is designed around covered losses rather than routine deterioration. Storm damage is different and depends on the policy. For a single damaged pane, compare the repair estimate with the deductible before filing a claim.
Is HELOC interest tax-deductible if the money pays for new windows?
It may be. Interest on a home equity loan or HELOC can qualify when the loan is secured by your home and the money goes toward buying, building, or substantially improving that same house. The usual mortgage-interest limits still apply, and the deduction only helps if you itemize. Keep the window contract and loan records together. A tax professional can then look at the actual project and debt amount rather than guessing from the words “home improvement” on an invoice.
Before Anyone Comes Out to Measure
Walk through the house with a notepad before calling for estimates. Give every problem window a short description: fog between the panes, air at the sash, soft wood at the sill, water staining, or a sash that will not stay open. Then put the estimates next to that list. If one contractor prices twelve replacement windows while another explains that eight are sound and four need specific work, you have something concrete to ask about instead of comparing two bottom-line numbers.
Keep the list after the work is done. Next winter, it will show whether the windows that were left alone are behaving the same way or whether the problems are beginning to spread.
