We have a custom built home that is almost 10 years old and is a 1400 square foot bungalow with 2×6 construction. We have noticed that the house doesn’t seem to be retaining heat as well as it should. Our basement is insulated and half of it has been finished. Our heating costs are quite high when compared to other homes similar in size and larger.
Recently we had a company come in with an infrared camera to video tape the house; they said that we didn’t have any missing insulation in the walls or attic; but we did have pretty severe thermal bridging in all walls along the ceiling and some along the floor as well. They also told us that we have 3 windows that have lost the seal. The windows obviously need to be repaired or replaced.
We think that thermal bridging is probably a common problem in all homes, but would like to try repair the problem and bring our heating costs down. Also how do we determine if it is as severe as they are suggesting. We don’t believe that they would exaggerate the situation because they do not have any ties to, nor do they recommend contractors names to use for repair. Their only service is to video record the home and then provide a CD with the video along with a written report
What would you suggest is the best method to repair thermal bridging, is it something we can do on our own? Also can you give us an idea on what the repair should cost?
With the expanding use of high-tech equipment for testing in homes, there is a considerable broadening of the base of knowledge and information that we can acquire about our homes. We must be careful not to get too caught up in the wonder and awe of these fantastic new technologies and forget that their use is only as good as the operator’s knowledge of the results. Raw data from an infrared camera is not useful unless we understand house construction and know what the images mean and how it can help us to fix any deficiencies.
To simplify it considerably, infrared thermography, as it is technically referred to, is a picture of an object with a camera that detects variances in temperature rather than normal light. A thermographic image of a home, taken from the front or rear yard, will often have several different colours, which display variations in the temperatures in these areas. Some colours show warm areas and other colours show cool areas. In a new home like yours, we should see a fairly uniform colour in the exterior walls and attic, due to the high level of insulation and air-vapour barriers. This temperature variation will also be largely dependent on the outside temperature. Ideally, the thermography is most valuable when there is a large difference in temperature between the interior and exterior environment of the home. Hot summer days and cold winter days may be the best times to determine areas of heat loss or air movement through the envelope in a typical home.
The way this technology helps us in homes is to determine, without any destructive testing, if there are any areas of temperature variations in the exterior walls, floors, or attics, collectively known as the building envelope. The proper use of this system can almost appear that we are looking through walls. By simply taking thermographic “pictures” from the exterior of the home, we can tell where the trouble spots may be. The way this can be extremely beneficial in building analysis is to determine areas in the building envelope which may have missing insulation, air leakage, moisture damage, or as in your situation, thermal bridging. The ramifications of missing insulation are obvious, but evidence of thermal bridging can be much more ambiguous.
Thermal bridging is the term used to describe an area of relatively high heat flow compared to the rest of the building envelope. When two or more pieces of wood, metal, or other solid materials in the building envelope are adjacent, without insulation in between, we can have thermal bridging. In the dead of winter, or a hot summer day, this can cause areas that are susceptible to condensation due to the varying temperatures with the rest of the envelope. Condensation may lead to moisture damage, which may allow areas of air leakage and increase the problems.
The solution to thermal bridging is to add insulation or “thermal breaks” in known problem areas when the house if built. In your case, this may be missing or poorly done, primarily in areas where the walls meet the ceiling and floors in the home. The difficulty in repairing these areas now is the limited access to install insulation or other components. The floor joist spaces, a very common problem in new homes, may be accessed through the basement, but the top of the exterior walls will be difficult to get to. Exterior soffits or sections of siding may have to be removed to allow installation of blown-in foam insulation or other materials.
My only concern, as stated previously, is the actual existence of true thermal bridging or whether simple air leakage, due to missing vapour barrier or proper air sealing is the culprit. Thermographers should be well trained in how to analyze the colour variations in their images, but if they are not highly experienced they may not know precisely what the data represents. What they describe as thermal bridging may be simple air leakage or other defects that is causing the heat loss. Other analytical techniques, such a “blower door test”, or smoke pencil testing may help rule out air leakage as the problem. Either way, consulting a building envelope specialist to analyze the video, do further testing and provide methods and costs of repairs should be your next step.