Interior and exterior doors: life expectancy, cost and more

Doors let us into our homes, keep out unwanted guests and pests, protect us from fire and the elements, slam when we need to make a point, prop open when we're feeling inviting and lock up tight when we're not. They've been doing their jobs for thousands of years and have gone through many iterations since their early days.

Even the most advanced doors around today won't last forever -- although some might come close. Below, you'll find a breakdown of different kinds of doors, how long they last, rough prices, pros, cons and even a few suggestions for use.

Exterior doors: it's a hard-knock life

The portals to your home, exterior doors have a difficult job: they have to be tough, insulate well, open easily, lock and look good doing it all. They last a lot longer when protected some from the elements by an awning, enclosed entryway, screen or storm door. Here are the most common types of exterior doors:

• Vinyl. Vinyl doors are rarely the main event. For exteriors, they're most often used as screen or glass doors. You won't need to paint or really do anything to them during their lifespan, which is typically around 20 years. They usually run anywhere from $50 to $200, depending on how much glass is used.
• Fiberglass. Advancements in fiberglass door construction have made these indistinguishable from real wood doors pretty much right up until you knock on one (and even then it's tough). They don't warp, rust or split, and they're thermally efficient. A fiberglass door is good for a lifetime (well over 100 years). Costs range from around $200 for a basic, no-glass/no-frills unit up to nearly $5,000 for a decorative and protective front door that's sure to impress.
• Steel. A fire-rated steel door can take a beating like no other. Look for units that have an insulating core to keep unpleasant temperatures outside where they belong. These doors last a lifetime (100+ years), and they don't cost an arm and leg, usually coming in between $75 and $500.
• Wood. There's nothing quite like a nice, real-wood door. Price, quality, durability and life-expectancy vary dramatically by wood type, with pine being at the bottom end and hardwoods occupying the top. A pine door lasts around 20 years, cedar about 40 years and a hardwood like mahogany 60 or more. Because of all the different options, the cost can range from $200 for pine with glass to $10,000 for some hand-carved hardwoods.

Other types of exterior doors include these:

• Sliding glass. You can find these available in many different materials and styles, with prices that fall into the ranges above. Because of the hardware, these doors typically last about 30 years (more with service).
• Screen, security and storm. These are great for protecting your entryway door from the elements and are available in all of the materials above -- but rarely found in wood. They usually last upwards of 30 years.

The ins and outs of interior doors

Doors inside your home don't take nearly the beating that exterior doors do. Most doors are in place for privacy reasons, so they don't need to be insulated or even particularly sturdy.

Wood doors are the most common for home interiors, and they come in two varieties: solid and hollow. Solid wood interior doors can last as long as the house they're in, but hollow ones are likely to need replacement in 20 to 30 years. Costs range from $30 for the low-end, hollow doors up to $500 for solid hardwood. You can find them as single-piece units, folding doors or even French doors.

Whatever materials you opt to use for your home's doors, don't forget about add-ons like weatherstripping, draft-blocking thresholds and fire-proofing. They might not add to the life expectancy of your doors, but they'll make you and your home more comfortable and secure.