Cold air revealed via IR camera. Air movement is encouraged by creating a negative pressure environment within the house using a blower door setup
There was a period of nearly 18 months during which we worked exclusively on renovation projects in attics. This was not by design, nor was it the result of a new business plan; it was purely coincidental. Each of the homes we worked on during this period had originally been built some time between 1890 and 1940, which is typical in the Greater Boston area. In dismantling the existing attic areas our team uncovered some fantastic original detailing, as well as some construction techniques that left much to be desired. The only thing that was consistent was an inadequate level of insulation by today’s efficiency standards.
During the period that most of these houses were built, installing insulation was not a major consideration during construction. Historically, the heat escaping from the uninsulated walls and roof of a home did a great job of keeping things thawed. It also did a great job of ensuring the residents had to burn a lot of something (be it coal, wood, or oil) to keep warm. Heat was allowed to run up through the walls, into the attic and out, warming and melting the snow on the roof. Much of the heat also escaped through the eaves, which helped prevent ice dams, and also defrosted the gutter. Many homes in New England have split fascia with original wooden gutters that have lasted many decades.
Today, in an effort to conserve energy, insulation is added to new and old homes to make them warmer and more efficient. Adding insulation to a home originally built without, or upgrading inefficient insulation, is a sound decision, however, one that requires a thoughtful approach. When one changes the original design of their house, and disrupt the flow of heat, they may run into trouble. Thankfully, we are better equipped now than ever before with insulation technology and information.
It is not enough to simply add insulation to a house without stopping the movement of air through the concealed spaces in the walls, attics, basements, and chases. Without air sealing in conjunction with the insulating, a house may still be very inefficient and suffer heat loss and ice dams. Using information gathered by using blower doors and infrared imaging, we can discover how air moves through a house and how it affects temperature. Once the leaks that compromise the efficiency of the home are found, they can be stopped.
Here is a great example of the hot roof method in action. It has been used to successfully insulate and air seal in an attached single family home renovation several years ago. We gutted the entire attic and installed spray foam insulation along the top of the lower walls, and directly on the underside of the roof. We also sprayed the very bottom of the walls around the perimeter of the basement right along the rim joist. This effectively blocked the air flowing into the walls and floor from the basement and rising all the way up to the attic.
It was not possible to address air leaks in the middle section of the walls in this particular renovation. Nevertheless, the end results were striking. In the middle of the renovation project, there was a slew of wintry weather, which was a gift in that our team was able to see the results of our insulation scheme. In the photo below, the left side of the house is our client’s side. The icicles seen on the right side (not our client) indicate heat loss, resulting in melting and subsequent refreezing (AKA ice damming). The side with no icicles or ice damming is the result of properly insulating and air sealing.