6 Important Things to Consider Before Building a House Extension

Visions of a grand house extension have been filling your daydreams for some time, and now you’ve decided to make it happen. How best, then, to translate your mental wish list into the built reality of wood, stone, glass, plaster, and luscious upholstery fabrics? Design professionals listed on the AD PRO Directory have guided clients through this process time and again, and are keen to provide pointers that promise an optimum outcome for your home addition project and minimal hassle along the way.

Decide on the Program

“Be really clear on your goals, both aesthetic and functional,” says Benjamin McGriff, an architect with offices in both San Francisco and Brooklyn, “and try to prioritize them. This helps your architect evaluate options based on your emotional criteria—and may help them dream up even better options that you might not have considered.”

McGriff Architects extended a historic San Francisco home by adding a contrasting, contemporary volume at the rear.

Sam Frost

For the uninitiated, the road from fantasy to buildable plan is likely to have more kinks and branches to navigate than you might expect, and many factors can impact the viability of what you want to do. For example, an addition is rarely just a matter of constructing a space that didn’t exist before. “Sometimes people think about only the need for a brand-new family room without [considering] how that space should flow and complement the house,” says Eddie Maestri of Maestri Studio in Dallas. “The reality is, it’s always much more of a domino effect.” Improvements will likely be necessary in the rooms that adjoin an extension, and systems throughout the house—such as air-conditioning and heating—may require upgrades. “Or we might realize that we want to tie in hardwood floors, and to get that to look right we have to redo the floors on the whole first level.”


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Use the programming stage to ask yourself, “What else?” “That’s a significant part of my initial walkthroughs—stepping back and considering what can be improved upon once you have all of these craftspeople in your home,” says McGriff. “Because it’s intensive work, economies of scale make a big difference. If you’re interested in extending your kitchen by five feet, the next five feet won’t be twice as expensive.”

Create a Budget and Schedule

Building a home addition, everyone agrees, will almost certainly take longer and cost more than you expect.

To get a handle on the rough price tag, May Sung of SUBU Design Architecture in Los Angeles recommends bringing in a contractor early during schematic design. “We create an à la carte menu: how much for redoing the entire primary bath, how much for doing the kitchen with such-and-such cabinetry, and so on,” she notes. “Through that exercise, the client can whittle down from there.” Another strategy is to query friends who have done similar work. (Be careful, though, Sung advises: “Nobody’s friend ever tells them what they actually spent.”)