QUESTION: We recently bought a home with a cold-storage room in the basement. There is a vent on one wall near the ceiling. Should this vent be closed in the summer season? If so, any suggestions would be appreciated. John Martel
ANSWER: Cold-storage rooms in basements are one of the things on my "bad idea" list for homes in our area. I will indirectly answer your question by providing advice on how to warm up this room and eliminate it from your home to prevent some common problems associated with unheated spaces in modern buildings.
Before I begin my rant on why you should eliminate this type of room from your home, I will say that you should permanently cover and seal the wall vent to the exterior to prevent warm air loss in the winter from your basement. This is best done on the interior with moisture-resistant insulation, such as rigid extruded polystyrene or polyurethane blown-in foam. The insulation should be installed and caulked or sealed at the interior with a proper air/vapour barrier to prevent condensation from any small air leaks that may let warm air penetrate behind the insulation. Once this area is sealed, you should patch the exterior foundation or siding and go about the process of warming up the rest of the room for the reasons that will be provided later in this article.
Cold-storage rooms in basements, using cold air from the exterior, may seem like an environmentally friendly way to keep things like root vegetables and preserves from spoiling in the winter. Unfortunately, with most modern basements being used as rec rooms and complete living space, this can create some significant problems.
Historically, older homes with unfinished and uninsulated basements were used as cellars. These minimally heated areas below grade were ideal to house the mechanical systems within our homes as well as provide a cool, relatively dry location for winter storage of food. This did not often create a problem because the entire area of the cellar was unheated, except for some radiant heat from heating ducts or older boilers and pipes. Since the foundation walls were completely exposed at the interior, they remained warm enough to prevent excessive condensation. If they did become cold enough for condensation to form, or in cases of minor seepage, the area would usually dry out from normal air circulation before major problems occurred.
The modern problems with basements started to occur when we realized how much heat we were actually losing through our uninsulated basements and windows. This is when we began to add insulation to the interior of the foundation and seal areas of air leakage, like windows and gaps, to prevent heat loss. Once we accomplished this, we realized that the old cellar now became more comfortable and could be used for more than just storage. This was followed by the addition of heat registers or radiators to convert the basement to truly comfortable, conditioned living space.
This system worked well enough as long as we took proper measures to prevent excessive amounts of warm air leaking through and behind the insulated walls. If we did not do a proper job, typically with plastic air/vapour barriers, condensation and frost could easily form on the cold foundation walls. This frost would melt in the spring, when the foundation warmed, and wet the insulation and foundation interior. In many cases, rot and mould would form on the foundation and the framing and create what we all know as the damp basement smell.
While this short history lesson may seem out of place for your question, I am providing it before I summarize my comments about eliminating your cold room. Many newer homes, or ones with newer finished basements, have properly insulated and sealed walls over top of their foundations and windows that prevent air leakage. While these measures help to provide a comfortable living space in the basement, they also trap warm, moist air. Previously, much of it would have leaked out of this part of the building envelope. This warm air should not create a problem, unless it's allowed to cool below the dew point, normally by hitting a cold surface within the basement.
By isolating a single room without heat and compounding it with a vent that allows large amounts of cold exterior air to penetrate, you are providing an ideal location for that to occur. This is made even worse if you have stocked shelves up against the cold foundation walls in this room. This storage prevents air circulation, which may be your only hope in preventing major condensation and frost formation. If the foundation walls or other areas in this "cold room" remain wet for any length of time, mould and rot can easily develop.
All too often I have done inspections where there's a small, isolated room with a door in the basement that has been used for cold storage. Even without the exterior vent to allow cold-air infiltration, or a well-sealed door, I almost always see evidence of mould on the perimeter walls. On a concrete foundation in good condition, this mould may be easily cleaned. But if there are damaged wall coverings, framing or shelving, they must be torn out and discarded to rid the area of the smelly mould. Not only will this improve the air quality in the basement, it may also prevent health-related problems for occupants of your home who may be sensitive to mould.
So, rather than give you a suggestion for proper use of the exterior vent for your cold-storage room, I recommend sealing the vent and immediate removal of the door and any damaged or mouldy components from this potentially troublesome area.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home & Property Inspectors -- Manitoba (www.cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at (204) 291-5358 or check out his website at www.trainedeye.ca.