Can draperies be both understated and whimsical? They can in the hands of John Diekmann and Joel Klaff, whose backgrounds in fashion and theatre inform the creations that come out of their high-end custom window-treatment business, Workroom (1906 W. Belmont Ave., 773-472-2140).

While Klaff was away in New Orleans recently creating draperies for the set of Brad Pitt’s The Curious Case of Benjamin Button, we spoke with Diekmann about choosing the right treatment for your windows.

Men of the Cloth Joel Klaff (left) and John Diekmann emerge from behind some fabulous curtains at their Roscoe Villageatelier.

Consider function first. "Ask yourself, ‘Why am I putting drapes in this room-do I need privacy? Do I need light control?’ Function is primary, then you work the form around that," Diekmann emphasizes. "A lot of times people just want stationary panels because the light is being filtered through solar screens or woven bamboo shades. The drapery layer really isn’t crucial for function, so you’d treat that a little differently than if you need them both lined and interlined for a bedroom to keep light out."

Make draperies the backdrop, not the focal point. "People tend to pick fabrics that want to jump into the room," says Diekmann, who loves luxe fabrics but favors them in solids or tonal patterns that blend with the colors of walls and furnishings. "Say you have a room that’s entirely white and not very big, and someone wants big red velvet drapes. When you step into that room, that’s all you see. Your drapery is part of the box-the exterior interior. You don’t want it sucking the air out of the room."

Spend your money wisely. If you have a limited budget, Diekmann advises spending it on the functional layer first. "Say sun is an issue. Put up solar screens or shutters or woven wood shades first. Live with that, then when you have the money, do the decorative layer." He also suggests putting your resources into public rooms and those where you spend a lot of time, such as the bedroom. "Spend it on rooms you entertain in, rooms that are important to you. Do the other rooms more simply; as time goes on, you can upgrade them."

Go for the unnatural. Sunlight tends to burn natural fibers, so you’ll get more life out of your drapery if you choose natural-looking blends, such as linen-rayon or silk-poly. If you’re fussy about appearances, go for blends even if sun isn’t an issue; pure linen and silk wrinkle easily. Also, always use a lining, generally cotton-polyester, to protect fabric from yellowing and breaking down. (The only time you wouldn’t use a lining is with sheer panels.) Well-made lined drapes can be expected to last ten years or so.

Photograph: Katrina Wittkamp

Avoid grandiosity. Diekmann is not a fan of swags, jabots, and other swooping touches, not only because they’re fussy but also because they make a room look smaller. "They look great in Versailles," he says, but "your average urban residential space is small, and you don’t want to make it seem smaller. You want to make it look taller, you want it to look wider-just bigger in general." Simple panels or shades in subtle tones are more likely to accomplish that goal.

Use unusual details, but subtly. Diekmann loves whimsical embellishments. Among the examples in the showroom are peacock-feather trim bleached to match a taupe drape, sprinkles of black sequins on a black silk panel, and even a genuine black horse’s tail used as a tieback on a deep gray-on-gray damask. By keeping the flourishes monochromatic, they come across as tasteful rather than over the top. "Just under the radar, I call it," Diekmann says. "I like one thing to be odd and out of place in a room, but very quietly."

Give shutters an update. Shutters provide more control over the amount of light streaming into a room than drapes, which are either open or shut. To give shutters a more hip, urban look, stay away from traditional white wooden shutters with a center pole. Instead, choose deeply colored ones without the pole, and pair them with drapery in the same tones. Cocoa polymer shutters, for instance, look beautiful paired with a cocoa velvet drape. "Dark colors are something new and fresh," Diekmann says. "I like that little bit of pop without it jumping out at you." If you prefer a more traditional look, you can still give it an update by pairing the cocoa shutter with, say, a paisley drape in brown and mustard tones, or a sedate stripe.

Go for consistency from room to room. Drawing inspiration from many sources is fine, but ultimately you have to narrow your choices so you don’t end up with a mishmash of decorating styles. "I like the whole home to be not identical, exactly, but to have the same feel to it," Diekmann says. "The buzz is all at one level; it’s not screaming loud over here and you can’t hear it over there."

Look to the runways, past and present. "This business is a couple of years behind the fashion business," Diekmann says. "A lot of this Lucite stuff [Lucite-ball finials] you saw in jewelry a couple of years ago. I have some flame-stitched fabric that was so big in the ’70s. Missoni did it; it was kind of their signature, and that got really hot again. Retro prints were really hot and are still really hot. You see it in the bamboo prints and florals and paisley from the ’70s."

Be not afraid. Though he strongly prefers the muted and the tasteful, Diekmann says there is no right or wrong when it comes to window treatments or to design in general. "If you like it and it accomplishes your goal functionally and aesthetically, nothing’s wrong with it."

Photograph: Katrina Wittkamp