Properly insulated basement key to comfort on upper floors

Hey there, time traveller!
This article was published 07/11/2015 (3606 days ago), so information in it may no longer be current.

Question: I would appreciate your opinion about a room temperature problem I’m facing with the tenants of my house, a split-level with finished basement, built in 1984. The tenants have been complaining of cold in the living room, with temperatures of 15 C when the outside temperatures are around -20 C. An inspector visited and identified areas of air leakage in the living room walls, using infrared photo technology. The windows have also lost thermal tightness, as they have not been changed since construction. According to the inspector, the heating system was functioning normally. I discovered the basement beneath the living room was not being heated, and instructed them to do so. Even so, the tenants say they are registering temperatures of 18 C in the basement, 12 C at the living room floor and 16 C in the living room itself.

Is it possible for air leaks and drafty windows to cause an inability for indoor temperature to rise, with a functioning heating system? From what I understand air leaks and drafty windows simply cause the house to be less energy efficient and result in higher heating costs. Should I be looking into inaccurate temperature recordings, or other causes of this problem?

Thank you for any advice you may have regarding this issue. Sincerely, Ling Yuan Kong, Montreal.

ANSWER: Inadequate heat distribution in homes is a common occurrence and is contingent on several factors, not only leaky windows and walls. Maintaining a good comfort level will not only rely on the heating system, but just as much on air-leakage protection and thermal insulation levels. Improving these can be much more cost effective than other solutions and I will try and steer you in the right direction for this fix.

Making homes comfortable for the occupants in our bitterly cold winters has always been a challenge for Canadians, whether in Quebec, Manitoba or Nunavut. In the past, when fossil fuels were cheap and we were not fully aware of the damage we were doing to the environment by burning and pumping huge amounts of carbon into the atmosphere, we just turned up the thermostat to get cozy inside. While that allowed our homes to be comfortable, it didn’t stop considerable air leakage around doors, windows and through walls, attics and foundations. This major air leakage kept our indoor environment healthy, although quite dry, but was truly wasteful.

When energy costs rose dramatically near the end of the last century, we started to take more measures to stop heat and air loss, keeping the energy bills down. An appreciable benefit of this was homes not only became more efficient, they became more comfortable. Less cold-air infiltration meant less-drafty rooms, at the same time keeping the relative humidity from dropping too low. Both of these factors made the air in our indoor environments more like the outside during more temperate seasons.

Unfortunately, many homes had upgrades to insulation and air sealing only in certain areas, but not in others. What your tenants are experiencing is likely due to that scenario, all too common in split-level homes. As you have stated, the basement is finished, and likely insulated. This will maintain a comfortable environment in that area, but will also keep the rooms above warmer due to natural convective forces. That may be exactly opposite to the lower basement crawl space area under the living room, where the perimeter walls may have little or no thermal insulation. You may have recently added some heat to this area, but if the foundation walls are not insulated, much of that heat will be wasted heating up the concrete walls. To further this dilemma, having no insulation between the floor joists can allow additional air leakage, making the floor colder around the perimeter walls. With older windows above this area, further allowing cold-air infiltration, the living room will certainly be colder than other rooms above the insulated portion of the basement. It is definitely possible for air leakage, combined with a lack of thermal insulation, to make one room feel colder than others, especially if the thermostat controlling the furnace is located in one of the warmer rooms.

The first item to address is insulating the inside of the foundation walls — and between the ends of the floor joists — in the lower basement crawl space. There are several methods for this, but using foam insulation will minimize the difficulty in air sealing this hard-to-get-at location. Secondly, caulking or sealing the areas around the older windows and behind baseboards will help prevent heat loss and drafts. Ensuring the crawl space has adequate heat will be the final piece of the puzzle to warming up the living room. Increasing wall insulation or upgrading older windows in the living room should also help, but will be much more costly than the other remediation.

Poorly insulated and sealed areas in your home can indeed create an environment that is hard to keep comfortable, especially if other areas do not have the same challenges. Upgrading these, by insulating the cool basement below and sealing up the drafty areas in the walls and windows, will not only keep the energy bills lower, but also provide a much more comfortable room with temperatures closer to those in the rest of the home.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.

trainedeye@iname.com