But your family is growing (or shrinking, perhaps), and you would like to do something to enhance the livability and the value of your home.

Both goals are attainable if you think long and hard about what you want to do.

If you want to remodel just to increase your profit when you sell your house, stop reading. This is not about quick turnovers and making a killing in real estate.

This is about improving your home, and choosing projects that will improve the quality of your life and that of your family. If, at some place down the road, it means that you will sell your house for more than you paid for it, so much the better.

You can't go wrong with a deck, siding, windows or updating a bathroom or kitchen.

If you want to know what's hot and what's not in your neighborhood, ask a real estate agent. It's an agent's job to know what people are looking for when they buy and when a remodeling project might be out of place in scope and price.

"Whether you are ready to sell or not, an agent should have the experience to tell you what not to do wrong," said Joanne Davidow, manager of Prudential Fox & Roach in Philadelphia.

If you live in a house where the windows rattle in a slight breeze and sitting with your back to one in the winter will give you a stiff neck, then you should consider replacing them.

Will you get back what you spend on them when you sell the house?

According to the most recent "Cost vs. Value Report" compiled by Remodeling magazine in partnership with Realtor magazine, a Philadelphia-area homeowner who spends $10,243 replacing 10 old windows with vinyl-clad, double-glazed windows should expect to recover 73 percent of his investment at sale time.

That's not 100 percent, but it isn't bad.

Consider this, however: Adding energy-efficient windows (wood or vinyl-clad) can save the homeowner between 27 percent and 33 percent on the annual heating bill, according to the Efficient Windows Collaborative at the University of Minnesota.

Rudy DeFinis, owner of DeFinis & Sons, a Northeast Philadelphia window company, said that when the annual savings on heating bills are considered, the return on installing energy-efficient replacement windows is higher than just resale value.

"Sixty percent of the heat loss from a house can be blamed on poor-quality windows," he said.

It's a great marketing tool to those who look at all costs associated with a house before making a decision on whether to buy.

Siding replacement — the method most homeowners use to avoid periodic painting — is considered a remodeling project. And the use of vinyl siding is becoming very popular as the baby-boom generation ages and grows increasingly unwilling to stand on 40-foot ladders for several weekends.

The typical replacement-siding job (about 1,250 feet) costs $7,817 in the Philadelphia area, according to the Remodeling/Realtor survey. For a home seller, the payback is about 75 percent.

Before the siding goes up on the house, make sure the contractor covers the exterior walls with some sort of "house wrap," a membrane that prevents air penetration and makes a house more energy-efficient.

"Installing a house wrap such as DuPont's Tyvec before installing the siding is standard with us," said Kirk Davis of A.H. Davis & Son in West Chester.

But not all the siding Davis installs is vinyl. He is doing a lot of fiber-cement composite siding, "which has the look of wood and comes primed from the factory," Davis said.

"For some buyers, vinyl siding detracts from the value of real estate rather than adds to it," he said.

He added that vinyl manufacturers were introducing products that look more like wood.

The resale value of vinyl siding — or aluminum siding, for that matter — is not consistent throughout the Philadelphia area. If you're talking about a Philadelphia brick rowhouse or stone twin, re-siding the fascia or wooden bays with vinyl or aluminum siding can often lower the resale value.

That's because, in many cases, siding is being used to hide damaged wood. This may spare some expense but most of the time fails to address the cause of the damage — usually water from a leaky roof or improper drainage. The damage worsens because it is covered and can't dry without air.

With seller disclosure now the law in Pennsylvania, this kind of cosmetic treatment to hide more serious problems can have costly legal and financial ramifications.

If you are looking for the greatest financial return and immediate gratification, why not build a deck or add to an existing one? About once a decade, a homeowner upgrades, expands or replaces a deck.

Many builders and real estate agents suggest that the deck be designed as an extension of the living space, not an appendage to the house.

How big should your deck be? Doug Walter, a Denver architect, said most people tend to build their decks too small for furniture and function.

"Add a couple more feet than you think you'll need," Walter said. "Every inch will be used."

There are about 30 million residential decks. More than 6.5 million decks are built in the United States annually, at a total cost of $1.9 billion to $3 billion.

The return on investment in a deck has increased over the last eight years, while the cost of building one has remained about the same.

A 16-by-20-foot deck in the Philadelphia area cost nearly $7,000 to build in the 1996-97 Cost vs. Value Report, of which 80 percent could be recouped at resale.

In the current report, the same deck costs $6,837, of which 97 percent of the cost can be recouped at resale.

There is a huge difference between the two decks, though. The 1996-97 deck was constructed entirely of pressure-treated lumber. The 2003-04 deck had pressure-treated pine joists but decking made of composite lumber and a railing system of composite lumber or compatible vinyl.

There are two reasons for this. The first is that pressure-treated lumber is too maintenance-intensive, while composite lumber generally requires little or no maintenance.

Three years ago, Iacobucci Homes in Delaware County, Pa., upgraded its deck options to buyers since "maintenance-free materials are what today's buyers are demanding, and power-washing and staining is out," according to marketing director Edward J. Deisher.

So Iacobucci shifted to Trex, a composite lumber, and vinyl.

The other reason is concern about using lumber treated with the pesticide chromated copper arsenate, or CCA, which was officially banned for residential use Jan. 1.

Although there is debate over CCA's long-term health effects, a lot of homeowners are looking at it as a potential liability along the lines of asbestos and lead-based paint.

If there's a rule of thumb for remodeling projects, it is: Don't overdo it — or at least don't over-remodel for your neighborhood.

A corollary to that is: Don't undertake a huge remodeling project in hopes of making a killing when you sell.