A 16-by-24-foot master suite addition to a house with midrange fixtures and finishes costs a national average of $103,884, according to Remodeling Magazine’s 2014 Cost vs. Value Report. For a larger, upscale suite with luxury appointments, the price tag jumps to $224,989.

Master suite building basics

Bumping out your house to add a master suite means giving up yard space, excavating, pouring a foundation, framing — the whole shebang that requires the full range of tradesmen, from roofer to plumber to tile-setter.

You’ll need zoning approval and building inspections, expanded heating and cooling systems, and probably an upgraded electrical panel, water heater, and burglar alarm, too.

Think outside the bump-out

If you take advantage of existing space for your master suite addition, you can trim 20% to 60% from your budget. Here’s how.

  • Build up instead of out: Add your master suite on top of ground floor space — over a porch, garage, or previous addition. The disadvantage? Ground-level space is easier to age into.
  • Steal underutilized space: Incorporate that rarely used guest room — even better, that extra bathroom — into your master suite. You’ll save thousands if you can tap into existing water and sewer lines.
  • Finish unfinished space: Convert unfinished basement, attic, or even garage space into a master suite. Because you don’t have to build a foundation, exterior walls, or a roof, you’ll save 50% to 60% compared with a full-scale addition.

Gift that keeps on costing

Your master suite expenses don’t end when the last faucet and light switch are installed. Every month you’ll pay higher energy bills to heat, cool, and light your new space.

If you add 600 sq. ft. to a 2,000-sq. ft. house — 30% more space — your energy bills likely will grow by 30%, too. Your property tax bill may increase by a larger percentage, because you’re adding space and installing a bathroom, which tax assessors value at a higher rate than other rooms.

Be realistic about payback

Adding a master suite will make a big difference to your life, but may not equally impact the value of your house. If yours is the only master suite on the block, you’ll recoup less than if master suites are standard in your neighborhood.

The national average midrange master suite paid back 67.5% of its cost, according to the latest Cost vs. Value Report, down from 82.4% in 2005. The average return on an upscale job was 56%, down from 80.1% eight years ago. But not everything is about money. If you plan to stay in your house for another three to five years, adding a private oasis could just be … priceless.