Fiberglass Batts
Cost-effective option, but be careful during installation to avoid gaps, which will compromise efficiency. This insulation is porous, even when jacketed with foil, and requires a vapor barrier.
How to Prepare Your Space for a Wine Cellar Installation
Wine must be stored at a constant, cool temperature, with humidity between 50 and 70 percent, minimal exposure to light and UV rays, and low vibration. To create these conditions, cellars must be built with quality insulation and a vapor barrier, especially if the wine cellar will be refrigerated. If the cellar will not be refrigerated, good ventilation is recommended inside the cellar. Additional preparation includes framing and electrical recommendations for the cellar.
Insulation Requirements
Wine ages best in an environment where temperatures stay between 55°F and 60°F, without sudden swings. Quality insulation acts as a shield, protecting the cellar from external heat and cold. The thicker the insulation, the better, but wall thickness—typically 4 inches for interior walls and 6 inches for exterior walls—limits how much can be added.
In actively refrigerated cellars, better insulation shortens cooling unit run cycles and reduces energy use. In passive cellars, better insulation protects against extreme temperature fluctuations. For walls facing conditioned interior spaces, insulation rated R-13 to R-19 is recommended. For exterior walls, ceilings, or walls and ceilings facing unconditioned spaces (such as garages and attics), R-30 insulation is recommended. Exposed and raised floors also should be insulated with a vapor barrier.
Where floors sit directly on or below grade, insulation is often impractical, but concrete should still be sealed to block vapor transmission. Insulation must form a continuous barrier across all walls, ceilings, and floors to maintain stable cellar conditions.
Rigid Foam
Higher performance than fiberglass batts, rigid foam boards are a common option for wine cellars. This insulation is porous, even when jacketed with foil, and requires a vapor barrier.
Closed-Cell Spray Foam
Closed-cell spray foam insulation is the best choice for wine cellars, because it provides the highest R-Value per inch and also acts as a vapor barrier. It is the most expensive insulation. When using spray foam, it is important to make sure that all cavities, corners and edges are filled, without any gaps.
Vapor Barrier
Proper wine storage requires humidity levels between 50% and 70%. In refrigerated wine cellars, the space must be constructed to be airtight when the door is closed. To prevent vapor migration through the walls, a vapor barrier must be installed or closed-cell spray foam insulation must be used.
All gaps, including those around the door, must be fully sealed. Without a proper vapor barrier, moisture from outside the cellar will enter the space, leading to condensation and mold within the walls, excess condensation inside the cooling unit, shortened equipment lifespan, and potential water damage to bottles, racks, and cellar surfaces.
Material to Use
The most common barrier is 6 mil polyethylene sheeting (aka Visqueen).
Wrap the Insulation
A moisture barrier should be installed on the “warm side” (outside) of insulation.
Sealing the Barrier
Meticulously overlap seams by at least 6 inches, sealing all joints and penetrations (such as electrical boxes and pipes) with high-quality, non-porous tape.
Completion
The cellar should be airtight when construction is completed.
Framing & Construction
WALLS
When framing a wine cellar, thicker insulation provides better protection against temperature fluctuations. Interior walls typically use 2" x 4" studs, allowing for approximately 4" of insulation, while exterior walls generally use 2" x 6" studs, allowing for about 6" of insulation.
Tip: Interior walls should achieve at least R-12 insulation. Exterior walls, or any walls adjacent to unconditioned spaces, should be better insulated, ideally with R-30 insulation.
FLOOR
The most common basement floor construction is poured concrete. If the floor is on or below grade, insulation is not required because ground temperatures remain relatively stable. However, the floor must be sealed to prevent moisture transmission into the cellar.
If the floor is raised and not in direct contact with the ground, it must be insulated and equipped with a vapor barrier, following the same standards as exterior walls.
CEILING
Ceilings exposed to unconditioned spaces or the exterior should be insulated and sealed with a vapor barrier, similar to exterior walls. Ceilings adjacent to conditioned spaces should also be insulated and vapor-sealed, consistent with interior wall construction.
DOOR
An exterior-grade door is recommended for wine cellars. These doors feature weather stripping and door sweeps designed to create an airtight seal.
When using frameless glass doors, such as those found in shower-type installations, it is crucial to minimize gaps as much as possible with the use of door sweeps and seals to reduce infiltration from the ambient space and maintain an airtight environment inside the cellar.
Glass Panels
Glass panels are increasingly used to showcase wine collections. Most installations use single-pane or double-pane glass panels.
Single-Pane Glass
Provides a cleaner, unobstructed view but offers only half the insulation (R-value) of double-pane glass.
Double-Pane Glass
Improves thermal performance, reducing temperature swings and thermal transmission into the cellar.
Cooling System
When incorporating significant amounts of glass—especially single-pane—into the cellar design, it is critical to account for the glass in the thermal load calculations to ensure the cooling system is properly sized.
Cooling Unit Electrical Requirements
If the wine cellar will have a refrigeration system, it must be supplied by a dedicated electrical circuit. Depending on the installation, the cooling unit may connect via a standard plug or be hardwired directly to the circuit.
Most wine cellar cooling units in the U.S. operate on 110V / 60Hz power; however, some larger systems require 220/230V.
Tip: 220/230V systems are sometimes marketed as "HE" (High Efficiency), but true efficiency gains typically occur only with 220/230V systems operating on three-phase power—not standard single-phase residential systems.
Circuit Size and Power Requirements
Check the cooling unit specifications to determine the required circuit size:
- Most systems require a dedicated 15-Amp circuit.
- Larger systems may require a dedicated 25-Amp circuit.
Inrush (startup) power draw is usually higher than the unit’s normal operating load. This is normal. Electrical circuits are designed to accommodate these brief surges.
Tip: Avoid connecting the cooling unit to a GFCI-protected circuit, as the initial surge may cause nuisance tripping.
Guidelines for Dedicated Circuit
The cooling unit's dedicated circuit should not share high-load devices such as:
Motor-based Appliances
(eg Hair Dryers)
Vacuum Cleaners
Garage Door Openers
Large Televisions
Lighting Power Considerations
Use low-heat lighting in the cellar to avoid unnecessary heat generation. LED fixtures are strongly recommended, as they produce minimal heat compared to incandescent bulbs. Low-draw devices such as LED lights or computers can usually share a circuit with your cooling unit, without issue.
Preparing your space for a wine cellar requires creating a well-insulated, properly sealed environment designed specifically for wine storage. Although costs vary depending on the size, complexity and desired aesthetics of the project, proper preparation is essential to ensure the cellar protects your wine and performs as intended.
