Bob did an inspection shortly after the big snowstorm hit the DC area last week, and it provided a great opportunity to illustrate how poor insulation can cause big issues with ice dams.
Even though there were no indications of water intrusion in the interior of the house, it was obvious that there was ice damming going on.
Water has penetrated through the eaves on this house, and is seeping down the brick exterior, where it saturates the brick and refreezes. This can cause damage to the brickwork, shortening its life.
The ice dam evidence outside prompted Bob to pull out his Thermal Imager. Taking thermal images is not part of a regular home inspection; in this case he was using it to find possible water damage inside. Although he didn’t find water damage, he did find some examples of why the house had ice dams.
The thermal image revealed a joist space on an exterior wall without any insulation at all. This patch could allow warm air to escape into the attic space and cause the snow on the roof to melt from underneath.
Snow that melts unevenly can be a clue for where to look for missing insulation. Here, the space between these two dormer windows was a closet.
The thermal camera revealed the issue:
Another joist space was missing insulation. This space would be vulnerable to water damage.
Thermal pictures of one ceiling revealed cold stripes. When Bob got into the attic, he found the source.
Batts of insulation were compressed around trusses, leaving bare spots over some of the joist areas. The batts should have been cut to fit around the trusses. Also, whenever insulation is compressed, its R value is reduced.
You don’t necessarily need a thermal camera to find gaps in your insulation. All you need is a really cold day. Run your hand along the walls and ceilings, especially at the edges and corners. If one area feels cooler than the others, there’s a good chance it’s underinsulated.