How long do windows last; plus signs it's time to replace yours

They let in tons of light and summer breezes, but shoddy windows also waste energy, which means it's important to know the answer to the question 'how long do windows last.' Here’s an overview, plus how to know when it’s time for an upgrade.

More than the sum of its parts—a frame around panes of glass—a window floods your home with daylight and fresh air while shielding out bugs, rain, and snow. But windows aren't just about what they look like while you're inside. No matter the type of windows you have—rectangular, square, or bay—windows are an expression of your home’s architecture, just like the trim, siding, and front door. After years of weathering storms, expanding and contracting, even the best windows can begin to look tired. 

If you think it’s time to replace your windows, arm yourself with information that will get the best windows for your budget.

How do you know when it's time to replace windows?

Windows last a long time, but eventually they need to be replaced. The signs of wear show themselves in a few ways. From the inside of the house, if you notice beads of water between the panes of glass—called the glazing—the weathertight seal has failed. That allows the insulating gas to leak out and condensate seeps in. You might be able to forgive the way it looks, but a window with a busted seal is much less energy efficient. If the window is hard to open—the pulleys don’t work, there are too many layers of paint sealing it shut, it slams closed by itself—a newer version will be easier to operate. From the outside, if you notice substantial rot beyond the point of a spot repair, a replacement is in order.

Consider storm windows to boost energy efficiency

If the windows are structurally sound, older single-pane style, or have a broken seal, you can significantly enhance the energy efficiency by adding a storm window to the inside or outside of the home. A well-sealed, low-e coated storm window can reduce air leakage by 10 percent and block 35 percent more solar heat gain than the window alone. Adding them to the interior tends to make more sense because they’re easier to install and remove.

• See also: How to install a window yourself

On average, how long do windows last? 

How long windows last will depend on the type of window you have. 

Generally speaking, the material around the glass, whether it's wood or a man-made material, is always more robust than the glass. Depending on the material, a window frame can last from 20 to 50 years if it's well maintained.

The warranty on a window is really two parts: one covers just the glass, the other speaks to the non-glass parts of the window like the hardware and frame. The glass in a window is typically covered for about 20 years, guaranteeing you the energy-efficient gas between the two panes won’t escape. While the window frame might have a warranty from 20 years to the duration you own the home, if the glass goes bad, you might have to replace the upper or lower sash containing the defective glass, or the entire window. 

When shopping, don’t buy windows with glass warranties that are less than 10 years. The better, more reputable brands offer warranties from 20 years and up. Read the fine print carefully. Some brands will cover the replacement parts for the glass and non-glass parts, but not the labor to install them. Transferable warranties for windows are common too.

Below, we've listed out specific lifespans for different types of windows. 

• Keep reading: Vinyl vs. Fiberglass windows - which is better?

Wood window lifespan

The warranty on the non-glass parts of a wood window is usually about 20 years. If the window is cared for with routine maintenance—usually in the form of a fresh coat of paint every couple of years—a wood window can last indefinitely. However, wood rots so if the installation is wrong, it’s the most susceptible window material to getting damaged. Because wood requires so much maintenance, manufacturers now offer a range of man-made materials. Besides broken glazing seals, if the frame is rotting, warped, drafty, or difficult to open and close, it's time to consider replacing it.

Clad window lifespan

While wood is the clear choice for the warmth and versatility it brings inside, exposing it to the elements requires upkeep to look its best. That’s why manufacturers offer clad windows, which marry a wood window inside with either a vinyl or aluminum half outside. Both materials come colored from the factory and each is far less maintenance than wood. The warranty on clad window parts can range from 20 years to as long as you own the home. Aluminum is pretty bulletproof so unless the vinyl cracks in cold weather or distorts in hot, these windows can last for decades.

Aluminum window lifespan

Somewhat less common, aluminum frame windows are relatively low maintenance. Because aluminum resists rust, it requires only the occasional washing to keep the factory finish looking good. You can pick from several color options from the factory—that paint job is warrantied too—and it can also be repainted. But metal is a better conductor of heat so these tend to be less energy efficient than other styles. It’s common to find a limited lifetime warranty on aluminum windows.

• Keep reading: Metal windows and doors -  a buyer's guide

Vinyl window lifespan

Of the man-made materials, vinyl tends to be the least expensive, yet it is still low maintenance. From the factory, there tends to be fewer color choices, as saturated colors can cause the frame to heat up and warp. While they can be painted later on, that paint can become a maintenance issue down the road if it peels. Check your warranty first before painting. It’s common to find a limited lifetime warranty on vinyl windows and they should last decades unless the frame warps due to extreme temperatures.

Fiberglass window lifespan

Fiberglass is like vinyl in that it never needs to be painted, and it’s the most energy-efficient window material out there—and also the most expensive. Unlike vinyl, fiberglass doesn’t move much with season expansion and contraction and you have greater access to color options. The warranty on fiberglass is often a limited lifetime warranty.

Should I replace windows all at once?

If the budget allows, having all the windows done at once makes a lot of sense. You have more purchasing power and the retailer can likely give you better pricing on the window and or the labor to install them. But typically, the cost of replacing all the windows makes it a project that's likely taken on in phases. If that’s the case, start with the most problematic windows which are probably sapping your home's energy efficiency. If all the windows are in the same condition, then start replacing those that face the street so your home's curb appeal, along with the energy efficiency, get a boost.