1. Multitask the dining room …
Cost: $500 to $2,000
If you have an eat-in kitchen, your dining room is probably used for special occasions only.
“Why have a prime spot sit vacant except for two or three holidays a year?” says Susanka.
Use it every day as an office or homework room without giving up dinner-party capabilities. Install doors ($300 to $500 each, with labor); add shelves or a cabinet for supplies; and invest in fitted pads to protect the tabletop.
For more flexibility, try a table like homedecorator.com’s $629 Mission Table Cabinet, a sideboard that — amazingly — telescopes into a full-size dining table.
2. … and the guest room
Cost: $100 to $3,000
Stop dedicating a whole room to infrequent out-of-town visitors.
With a decent air mattress, futon, or pull-out couch, you can lose the spare bed and use the room for day-to-day needs. (If you go with an air mattress, make sure to choose one with a built-in reversible motor to simplify the inflating and deflating.)
Add furniture, and what was only a guest room can double as a media or game room or home office.
3. Add a powder room
Cost: $3,000 to $6,000
Adding a first-floor powder room is simple if you have an unfinished basement or crawlspace for running the new pipes. Look for an existing room — a coat closet, say — and you won’t have to build walls.
To save more, forgo the tile. The minimum space required by code is typically 2½ by 4½ feet, but you can often get an exemption to go even smaller.
4. Build a home office closet
Cost: $100 to $3,000
If your family is already bursting the seams of your abode, a home office might seem out of the question. But every household needs at least a small desk for paying bills and to anchor a wireless Internet system — and you can often fit it all in a closet or armoire.
At its simplest, all you need are five or six deep, sturdy shelves made from wood or a composite product, which can total less than $40 at a home center. In a closet, set the lowest shelf at 30 inches high so you can wheel up a chair.
5. Bring the laundry upstairs
Cost: $5,000 to $7,000
Hiking up and down the stairs with laundry is enough to make anyone wish she could trade up. Instead, just move the machines.
Today’s full-size high-efficiency washers and dryers are all designed to stack. You can steal the space — a little more than four square feet — from a closet, hallway, or nook.
You’ll need to run new pipes and wiring, so being near an existing bathroom helps keep costs down, says Raleigh, N.C., architect Tina Govan. Make sure to include a drain pan to collect overflows or spills.
6. Open the floor plan
Cost: $2,000 to $4,000
A choppy layout of undersize rooms can make any house feel claustrophobic.
“People like the look of older homes, but not the way they function,” says Seattle architect Thomas Lawrence.
To open your floor plan without major expense, remove doors from rooms that don’t need them. Interior walls can come out for $2,000 to $4,000, unless they support the building or contain pipes — in which case a window or pass-through may be a more feasible solution.
7. Use built-ins to replace a closet
Cost: $4,500 to $6,000
If you choose to eliminate a closet to expand or enhance your living space, create some built-ins to get back the lost storage. A run of four- to 10-inch-deep shelving along a wall has almost no effect on the size of a room, says Corvalis, Ore., architect Lori Stephens.
And it can handle many times the capacity of a closet. You might spend $4,000 removing the closet and another $2,000 on new built-in cabinetry, or just $500 if you use assemble-it-yourself home-center cabinetry, such as the Billy collection from Ikea.
8. Build a bump-out
Cost: $6,000 to $12,000
Another trick to expand a home without a full-blown addition is called a bump-out. You hang extra space off the side of the house, sort of like an oversize bay window.
Structurally, it can’t extend more than about three feet from the existing exterior wall, but it can run nearly the whole length of the building — enough space to add an eating area to your kitchen or a closet to your master bedroom suite.
Because there’s no foundation work, a bump-out costs about $150 a square foot — or just $100 if you can tuck it under an existing roof overhang.
9. Finish non-living spaces
Cost: $15,000 to $30,000
Converting a full-height basement or garage into living space gets you an addition at half price. You’ll need a floor, ceiling, walls and more, but no structural work, no foundation, and no roof, so it’ll cost $50 to $100 a square foot — vs. about $200 for a true addition.
Attics are fair game, too, but more complicated because you may need to add a stairway and probably extend the plumbing, heating, and cooling systems a flight up. Doing all that brings the cost to around $150 a square foot.