How Long Do Windows Last? Lifespan by Frame and Glass

The window maker Pella states that vinyl windows typically last 20 to 40 years, fiberglass up to 50 years, wood 30 or more years with proper upkeep, and aluminum 15 to 30 years ¹. Those are a manufacturer's general ranges, not a promise for any window. Pella adds that lifespan depends on the quality and type of material, the local climate and weather, how well the window was installed, how often it is opened and how often it is maintained ¹.

The parts of a window also wear at different rates. The sealed glass unit, the balances and the weatherstripping can fail long before the frame does, and most of them can be replaced on their own. So the useful question is usually not how old the windows are, but which part is failing and whether it can be fixed.

Lifespan by frame material

Other sources give their own figures. HomeGuide, a cost survey, says windows should be replaced after 15 to 30 years, when the seals begin to leak, or when other damage makes them hard to open (February 5, 2026) ⁶. Pella's own fiberglass page says fiberglass windows are designed to last for decades ⁹. These figures come from companies, not from a government or standards body, so treat each as that company's estimate.

For how the materials differ in upkeep and movement, see window frame materials compared.

What warranties say, and what they do not

A warranty is a promise about defects for a set period. It is not a forecast of lifespan, but it shows how long a maker is willing to stand behind each part.

• Andersen lists 20 years on glass and 10 years on non-glass components across its 100, 200, 400, A-Series and E-Series products, transferable to a later owner ². Its 400 Series and 200 Series warranty gives non-glass parts of windows with wood exteriors five years instead of ten, and excludes condensation and normal wear and tear ³.
• Pella says all of its vinyl windows installed in owner-occupied single-family homes come with a limited lifetime warranty ⁵.
• Milgard offers a lifetime limited warranty, effective January 1, 2026, and an optional full lifetime warranty on some lines that adds accidental glass breakage ⁴.

"Lifetime" in a warranty is defined by each warranty, not by the life of the window. Milgard, for example, describes its coverage as lasting as long as you own your home ⁴. Read the terms for labor, transfer and exclusions. The window warranties explained article covers them.

The glass unit

In a double- or triple-pane window, the glass is a sealed unit. When the seal fails, moisture gets between the panes and the glass fogs. Pella describes condensation between panes of insulating glass as a sign the seal has failed ¹. Andersen's warranty for its 400 Series and 200 Series covers the glass against material obstruction of vision from a failed seal for 20 years from purchase ³.

A failed seal does not mean the frame is worn out. The glass unit can usually be replaced in the existing sash; HomeGuide reports $150 to $500 for glass replacement and $75 to $210 to repair a broken seal (February 5, 2026) ⁷. See the window glass replacement cost article.

Signs a window is near the end, and the repair to try first

HomeGuide's figures are national ranges dated February 5, 2026 ⁷. When the frame itself is rotted, HomeGuide notes that rotted frames are typically replaced rather than repaired ⁷, and that is usually the point where a window has reached its end. The window condensation article explains the difference between surface fog and a failed seal.

For drafts, the U.S. Department of Energy lists weatherstripping windows and caulking air leaks among the basic weatherization steps ⁸. For old single-pane windows, DOE notes exterior storm windows as an alternative to replacement, and estimates that low-e storm windows can save 10% to 30% on heating and cooling costs, depending on the window already installed ⁸. The window sash replacement article covers swapping a sash.

How often should windows be replaced?

There is no fixed schedule. A window is due when the frame fails or when repairs stop being worth it. HomeGuide's rule of thumb is to replace rather than repair when a window is more than 15 years old, in poor condition, or when repairs would cost more than half the price of a new window ⁷. That is one publisher's rule; a 20-year-old window with one fogged pane and a sound frame may still be worth repairing.

Should you replace all windows at once?

Not if only one or two have failed. When several are failing, doing them together may cost less per window. Pella's FAQ says replacing all windows at once can reduce labor costs and give a consistent look, while a phased approach works when the budget calls for it ¹. HomeAdvisor says doing several at once can cut transportation and minimum fees (updated June 17, 2026) ¹⁰.

What helps windows last

Upkeep and installation both matter. Pella says regular cleaning is one way to help windows last and keep working properly ⁵, and that wood frames need periodic painting, staining or sealing to protect them from moisture ⁹. DOE notes that windows not installed by trained professionals according to the manufacturer's instructions may have their warranty voided ⁸. Andersen's warranty excludes damage from improper maintenance and from failing to seal exposed wood ³.

If you are weighing a fix against a new window, the repair or replace windows guide walks through each symptom. When replacement is the answer, compare quotes from window installers.

We are not affiliated with the manufacturers named.

About these figures

• ¹ Reported: Pella FAQ lifespan ranges by material, lifespan factors, condensation between panes and replacing all windows at once, checked October 22, 2026.
• ² Reported: Andersen warranty comparison (20 years glass, 10 years non-glass, transferable), checked October 22, 2026.
• ³ Reported: Andersen 400 Series and 200 Series limited warranty glass term, wood-exterior term and exclusions, revised September 8, 2023, checked October 22, 2026.
• ⁴ Reported: Milgard lifetime limited and optional full lifetime warranty, effective January 1, 2026, checked October 22, 2026.
• ⁵ Reported: Pella limited lifetime warranty on vinyl windows in owner-occupied single-family homes, updated August 4, 2026, checked October 22, 2026.
• ⁶ Reported: HomeGuide statement on replacing windows after 15 to 30 years, dated February 5, 2026, checked October 22, 2026.
• ⁷ Reported: HomeGuide repair costs by repair type, frame-rot note and replace-or-repair rule of thumb, dated February 5, 2026, checked October 22, 2026.
• ⁸ Official record: DOE Energy Saver Guide on weatherstripping, storm windows (10% to 30% estimate) and installation to manufacturer instructions, checked October 22, 2026.
• ⁹ Reported: Pella statement that fiberglass windows are designed to last for decades, updated October 7, 2026, checked October 22, 2026.
• ¹⁰ Reported: HomeAdvisor note on replacing several windows at once, updated June 17, 2026, checked October 22, 2026.