Question: I was wondering if it’s advisable, or not, to leave a vacation home unheated during the winter months. It is well insulated and finished inside with drywall and knotty pine flooring and some stone tile. The water has been turned off and the plumbing fixtures have been winterized.
Thank you for your time, Fred Battistuzzi.
We have an older home in south-central Manitoba, which is approximately 100 years old, which we only use during the summer months. The house has a poured concrete foundation, which is less than 20 years old. We drain the water lines each fall. Is there any reason to keep even a little heat on during the winter?
Answer: Leaving the heat off in a seasonal building in Manitoba is possible and is done quite often by many cottage owners. There may be some negative consequences, depending on several variables within the building. Only actual trial and error will tell you whether these will be significant or not.
Turning off the heat in any building for an extended period of time in our harsh Canadian winter can lead to problems. That is because there are several items in the summer home or cottage that may be adversely affected by the dramatic changes in temperature and humidity. Plumbing fixtures, supply and drains are the most critical components, as they can become damaged if left with water inside. Because water expands when it freezes, filled pipes may freeze solid if left undrained. They will then expand, likely crack, and then leak badly as soon as the weather warms above freezing in the spring.
This can be avoided by completely draining all the supply pipes, drains, water heater, faucets and other fixtures and blowing out residual water with an air compressor. If your seasonal building was properly designed with all the supply pipes sloped to an exterior drain or valve the compressor may not be required. Also, all toilets and drain traps should be filled with plumbing antifreeze to prevent damage to these parts which require liquid to prevent sewer gas intrusion. It appears this is already in place in both homes in question, so should not be an issue in either case.
Most often, wall and ceiling coverings can be the next biggest concern when it comes to damage from the cold, dry weather. The type of materials used for these areas will often determine if any damage will occur, but also the amount of moisture in the building at freeze-up is a factor. The amount of moisture that can easily be absorbed and released by a particular wall covering may determine the degree it is affected by being unheated for a long period of time. Some wall and floor coverings, like the pine in the one building in question, may be completely unaffected by freezing temperatures, as it easily will absorb and release moisture. This "breathability" will prevent expansion and contraction due to frozen water vapour, that can be stored in less desirable finishes, like painted plaster in the older home. Even drywall, and various types of wall and ceiling panels, can buckle or crack if the temperature drops while the interior of the building is too humid. This is particularly a concern in cottages in lake country, where the ambient air may be very damp.
Another concern with shutting down an enclosed building in the winter is condensation and frost buildup, which can lead to mould growth. This has the same factors at play as in the wall covering concern, but may manifest itself in other areas. Closets, cupboards, and other areas with limited airflow may be subject to increased condensation. This may be a result of trapped, damp air that has not had a chance to dry out before the harsh weather arrives. Storage of various items in these locations will only make the situation worse, as they can further prevent dryer air from accessing these areas. The solution to this situation may be to completely empty all the closets, drawers and cupboards, or at a minimum leave them all open to improve airflow and allow trapped moisture or any condensation to evaporate.
How airtight the buildings are will be another factor to determine how much, if any, damage is done by turning the heat off for the winter. While air leaky walls, windows, attics, and doors may be very negative properties for a year-round home, it may be a benefit for this situation. If you have a lot of cold air intrusion, and exfiltration, in these areas it will prevent condensation issues inside the shuttered buildings. The older building in question may have these benefits, while the newer vacation home in question may not fare as well. In either case, additional ventilation may be required to prevent this issue from occurring. Leaving a fireplace flue open, bathroom exhaust fans running periodically, or even ceiling fans rotating slowly can help. Certainly, coming to inspect the buildings a few times throughout the winter, and letting some cool, fresh, dry winter air inside should help. This will also alert you to any obvious problems during your first winter shutdown, which could be nipped in the bud early, and low heating resumed if necessary.
Damage to building components are a possibility, due of lack of heating in a seasonal home. Taking measures to prevent condensation related issues is warranted, but only time will tell if they are serious enough to heat your properties year-round, or not.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (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 trainedeye.ca.