Anyone who purchases a home should be aware that many of its components have a limited lifespan. Appliances, the roof, and several other systems will eventually start to show their age and need to be replaced.

A deck isn't usually among the items people expect will need replacement. But many decks will only last for a couple of decades or less, and failing to upgrade them can lead to serious safety hazards. Decks in poor condition can give way beneath the weight of people walking on them, leading to serious injuries.

Certain factors will increase the possibility that a deck will deteriorate. McGarry and Madsen Home Inspection, a company in Gainesville, Fla., says deck materials and sealers will break down faster in direct sunlight. However, they'll also stay damp in shady conditions, promoting wood rot. Decks that receive partial shade during the day are most likely to have a longer lifespan.

Decking is more likely to break down if it is made of low-quality building material, poorly maintained, or has areas where rainwater will not drain properly. Rot will occur more quickly if support posts are directly in contact with the ground or if the deck is located close to the ground, allowing pockets of moisture to form. Individual spots of deterioration can also form, such as around a flowerpot that overflows when it rains.

In addition to the decking itself, the fasteners keeping components together might start to corrode over time. Karen Marsala, writing for Realtor.com, says many decks only have a lifespan of 12 to 15 years.

If you start to notice problems with your deck, you may be able to repair them before they become more extensive. Peter A. Kirsch-Korff, a California-based builder, says damage may be limited to a small area of the deck due to damp conditions, termites, or other problems. Fixing this area, and taking steps to alleviate any underlying problems, can help prolong the life of the deck.

However, you can also find yourself completing several small repairs over time due to problems cropping up in different parts of the deck. It can also be more cost-effective to simply replace the entire deck if there is damage to the structural components, such as rotted support beams or a sagging deck surface.

The lifespan of your deck often depends on the quality of the materials you choose for construction when building or replacing it. Franklin Building Supply, a company in Boise, Idaho, says you'll want to use decking that can withstand sunlight, moisture, or other conditions in the area where the deck is located. It also helps to use galvanized or stainless steel fasteners, and to design the deck so it has minimal exposure to moisture.

Several different types of wood are available for deck construction. John D. Wagner, writing for This Old House, says pressure treated wood is cost-effective and will last about 15 years. Sturdy woods—such as redwood, cedar, and mahogany—can last up to 20 years. Tropical hardwood, also known as ipe, has an expected lifespan of four decades or more.

Homeowners must also plan for regular maintenance to help keep their deck in good condition and extend its life expectancy. Franklin Building Supply says this includes regularly sealing and staining the wood to protect it from moisture.

You'll also need to be careful about what you keep on the deck. For example, grease from a grill can drip onto wooden surfaces and harm them. Planters and other items can trap water against the surface, increasing the possibility of rot.

As an alternative to wood, homeowners can choose to use plastic-wood composites. Jim Finlay, a Boston builder, says synthetic decking can last for several decades since it is not vulnerable to rot. It's also a low maintenance material, only requiring the occasional cleaning to keep dirt and mildew at bay.

Vinyl decking has similar benefits. Wagner says this material has good resistance to ultraviolet radiation and is usually offered with a lifetime warranty.