So you’ve visited local showrooms, went to design houses, flipped through home sites online, studied friends’ houses—and perhaps even found design inspiration in your own dreams. You have a clear goal, a budget, and perhaps a scrapbook filled with clippings, brochures and sketches. But you’re not quite ready to start your addition project—until you ask yourself the following questions:

1) How would you design your house if you were building it new?
Sometimes it’s hard to see what’s already there, like a wall or staircase. Try to imagine you were starting from scratch and creating your ideal home. That frees you to get really creative about what you want—and helps to prioritize your goals and wishes. Then you can look for ways to turn your present house into that dream house, through an addition, a remodeling project or a combination of both.

2) Will the addition add value to your home?
Even if you have no plans to sell anytime soon, you (or your family) will sell someday—and you might also refinance or take out a home equity line of credit, for which you’ll want the best possible appraisal of your home. So always consider the resale value of your project. It’s not that you’re going to turn a profit on your investment. So you might as well go into the job with realistic expectations about payback.

Because they’re among the costliest home projects, addition jobs often return less than remodels. A recent industry report estimated the following returns: A two-story addition with a family room downstairs and master suite upstairs (65 percent); master-suite-only addition (63 percent); bathroom addition (53 percent); and sunroom addition (49 percent). To maximize your payback, add amenities that are highly sought after in your area. If your neighbors have master suites and you don’t, then that’s a good investment. If nobody else on the block has one, your payback will be small.

3) Is there a lower-cost way to get what you want?
The downturn in addition payback doesn’t mean you shouldn’t add on—assuming you’re doing the project for your own enjoyment and intend to stay in the home for at least 5 years. But it does mean you might want to look for ways for you and your contractor to cut the costs of your project. And the best way to do that is to look for ways to eliminate or minimize the need to add on—by using an attic or garage, or by simply reconfiguring existing space.

4) Are there any zoning restrictions to consider?
Most municipalities have rules about what you can build where—including when you’re building an addition. This is where a qualified general contractor is worth the money. He’ll make sure the proper laws are followed and permits are pulled. If you live in a neighborhood with HOA’s, you’ll have to look at those as well.

5) How will your addition tie into the house?
Adding onto a home requires a bit of finesse to make it look like it belongs—while also taking advantage of all of the modern amenities available today. Your contractor and his architect will consider how the roofline connects to the house, how it will compliment the style of the house, from the interior and exterior finish materials to the windows to the utilities and heating and cooling—and at the same time create a functional, modern space that will provide maximum benefit to your family.

6) How much do you expect to spend on your addition?
Since every house, every site, and every family’s wish list are different, the only way to get a realistic estimate for your particular project is to talk to your general contractor. But as a general guideline, expect to spend anywhere from $100 to $200 (and up) per square foot.

Here are some average project costs for common addition jobs:

  • Bathroom Addition: $40,000
  • Upscale Bathroom Addition: $75,000
  • Family Room Addition: $85,000
  • Garage Addition: $60,000
  • Upscale Garage Addition: $90,000
  • Master Suite Addition: $105,000
  • Upscale Master Suite Addition: $225,000
  • Outdoor BBQ: $50,000
  • Two Story Addition (master suite over family room): $165,000

And there are long-term costs to adding on as well. Increasing the size of your home means increasing your energy bills, especially for heating and cooling. Plus, you can expect your property taxes to climb, since tax assessments are based on the home’s vital statistics, starting with its square footage. Add amenities that weren’t there before, like an additional bathroom, a hot tub, or a fireplace, and your assessment will jump even higher.