Building a wine room addition or converting an existing room for wine storage requires more than placing a few racks in a room. It takes knowing how to achieve and maintain the conditions that allow wine to age properly without spoiling -- or knowing the right wine cellar designer to hire and then following the specifications to the letter.

The most important requirement for an effective wine room is a stable, cool temperature (between 55 and 60 degrees) and a stable humidity (between 55% and 75%). "With wine storage, a steady temperature is more important than the correct temperature," says Fred Tregaskis, owner of custom wine cellar design firm New England Wine Cellars in West Cornwall, Conn.

Any radical temperature change -- from too hot to too cold -- can cause wine to spoil. A too-low humidity level can cause a cork to dry out and allow the liquid to evaporate, whereas a too-high humidity level can encourage mold growth.

Maintaining ideal temperatures and humidity involves installing insulation and vapor barriers in all walls and ceilings, and sometimes in the floor. Many wine cellar designers use greenboard as well. "The shell needs to be constructed with a vapor barrier and insulation, because it is basically a walk-in cooler when all is said and done," says David Spon, owner of Wine Cellar Concepts in McLean, Va., a custom designer, fabricator, and installer of wine cellars.

Courtesy WineCellarPro

Using climate control and humidification equipment that is specifically designed for wine storage is critical, because standard air conditioners and refrigeration systems remove moisture from the air, affecting the room's humidity levels. Some designers prefer split systems, such as the WineMate cooling system from Vinotemp. Self-contained units are also a good option, such as wall-mounted cooling systems from Breezaire and the ceiling-suspended Cellar Mate, designed by Tregaskis.

Racking systems for wine storage can range from simple redwood bins, single-bottle slots, or case shelves such as those from WineCellarPro to high-end, custom-built cabinetry in mahogany or walnut. The preferred wood for racking is rot-resistant redwood, which does not require finishing that would produce chemical off-gassing and flavor the wine.

According to Kathleen Valentini, owner of custom design and fabrication company Valentini's Fine Wine Line in Scottsdale, Ariz., wine cellar racking or cabinetry should be able to withstand humidity without warping or molding, and all-heart redwood fits the bill nicely. However, other hardwoods are frequently used.

Details such as tasting centers or tables, chandeliers, mosaic floor tiles, and hand-painted wall murals can add the finishing touch.