A White Paper by ChicagoWineCellarExpert.com
Wine Cellar Construction
Topic: The placement of insulation and a vapor barrier in a wine cellar.
Insulating a wine cellar provides a heat/cold break between the inside of the cellar and the adjacent spaces around the cellar. The fact that the ground temperature varies between 520 during Chicago winters and 640 in the summer confirms the reasoning behind insulation, even for exterior walls. A ten-inch thick concrete wall has an insulation factor of r1. Basically it is an open window to whatever environment lay on the other side. Insulation is cheap compared to buying a cooling unit that is twice the size required for the same room if properly insulated.
A vapor barrier, encapsulating the entire cellar, is required. Its presence between the foundation wall and the insulation prevents the migration of moisture from the outside to the insulation. Wet insulation will evolve over time into wet drywall, which in turn will evolve into mold. Typically vapor barriers are 6mil plastic with the seams between the sheets taped. The actual material of the vapor barrier can change depending upon the type of insulation used.
If the insulation is fiberglass batt, a 6mil plastic vapor barrier must be used. (With fiberglass, make certain that the batt is unfaced. No…, the coated paper on some batts will not suffice as a vapor barrier.)
Below are diagrams showing the proper placement of the vapor barrier when batt insulation is used. The first shows the vapor barrier dead against the concrete wall, between the foundation and the framing. This is always the preferred method, since it’s the easiest and provides less chance for the seal to break. If you find yourself placing a vapor barrier around an already framed room, the only approach possible is to wrap the stud cavity. Nail/staple the edge of the vapor barrier to the fist stud. Pocket the stud cavity with the vapor barrier, leaving sufficient ‘extra’ plastic within the cavity to accommodate the batt insulation that you will place into the cavity later. Nail/staple the vapor barrier to the next stud and proceed around the room. The second drawing below uses yellow to outline the vapor barrier using the technique just described.
Batt Insulation with vapor barrier against the concrete
Blown-in foam insulation does not require the placement of a 6mil plastic vapor barrier. The spray-in foam acts as its own vapor barrier. Foam has an insulation of R7/inch, so at least two inches is required in wine cellars walls, three inches in ceiling applications.
Blown-in cellulose insulation is manufactured with a mold retardant mixed into the basic slurry. The cellulose product itself will not mold, but it will hold water.
A note about moisture and mold:
If cellulose or fiberglass insulation become wet due to a lack of a vapor barrier and continues to experience added moisture, both insulation materials will become soggy.
Neither material will mold even in prolonged exposure to moisture. However, a wet patch of cellulose resting against drywall or green-board will eventually cause the
moisture to soak through the drywall, and water will reach the paper face of the drywall. Once this occurs, mold is a certainty. Even a mold resistant paint can only delay the appearance of mold.
There are two ways to use rigid foam board insulation. (This is the pink or blue stuff you see at Home Depot piled up in 4’x8’ sheets of one-inch to three-inch thicknesses.) Like blown-in foam, rigid foam board does not require a vapor barrier IF you mount it correctly. In addition, this is great stuff for difficult-to-vapor-barrier ceilings or places in the ceiling where hot mechanicals (i.e. heating ducts, hot water pipes, or radiant heating pipes, etc.) were placed overhead. Lastly, if the distance between the ceiling and the eventual drywall is only three inches or less, rigid-board is a great alternative. (For example, the bunker-room cellars in which the walls and ceiling are poured concrete and the ceiling is so low that the client wants to place the drywall as close to the ceiling as possible so that he can have as much head-room as possible.
There are two ways to place rigid foam, either directly upon the face of the stud and/or ceiling joist, or within the stud and/or joist cavity. (Sometimes you may have to do both to attain the needed three-inches of insulation (r19-r21 for a ceiling, r11-r14 for walls.) However, in either case the seams between the panels and the seams between the panels and the joists must be caulked. (Think water-pipe break in the floor above. Could standing water seep through the insulation and wet the drywall? The insulation boards are impermeable. Problems occur at the seams.) Below are drawings showing the proper placement of rigid foam insulation Rigid foam attached to the outer-edge of the walls or of the ceiling joist Rigid foam within the stud or joist cavity.
Last point, please remember that these insulation specifications are industry standard. If you purchase your cooling unit from Chicago Wine Cellar Expert or any of our competitors, everyone is going to assume that you insulated to at least r11 in the walls and r19 in the ceiling. Each will assume that a vapor barrier is present and that it is throughout the cellar.
Finally, if your cellar has windows or a door with a glass, each of us will assume that the glass is insulated (i.e. two layers of plate glass with an inert gas between the panes.) If these assumptions are not correct, the cooling unit size that comes out of our calculators will not be sufficient to maintain temperature in your cellar. As they say in computers, garbage in; garbage out.
One of the great benefits of our, individual business model is that ChicagoWineCellarExpert personnel will visit your site and sign-off on the wine cellar construction. Once the insulation and vapor barriers are installed, ask us to visit the site. The service is free and the peace of mind is immeasurable.
Whether its mold on the walls, or within the stud cavity, or a cooling unit that is under-sized, no one wants to turn a dream into a nightmare. Call me. I will come-out. Personal service is another of our guarantees.
Chicago Wine Cellar Expert